Núm. 1 - Caracterización - Sostenibilidad y Reciclaje

• Lightweight materials development for automotive engineering use. Manufacture and End of Life optimization through Life Cycle Assessment.

  H. Afonso González, J. Ibarretxe, E. Acha, U. Olaziregi Cuevas, A. Esnaola, A. Serras, A. Iturrondobeitia.

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 1 - Caracterización - Sostenibilidad y Reciclaje), 19

  
  

  Abstract

  With fuel economy and lightweight design becoming ever more significant due to the current materials, resources and environmental crisis, the manufacture of polymer composites for automotive industry use has experienced a steady growth in the last years and is expected to keep growing in the coming years. This means that there is a vast range of different polymer composites available in the market, with their unique properties, manufacturing processes and materials imbedded in them, each with their own set of impacts on the environment throughout their whole life cycle. The end-of-life treatment of a composite determines a substantial fraction of its footprint on the planet, and advanced treatments, namely pyrolysis can be used to obtain high value added compounds such as hydrogen and other light fuels. This study aims to address and quantify the impacts associated with the manufacturing and end of life treatments of an experimental glass fibre mat reinforced thermoplastic composite and compare them with the impacts caused by materials currently used in the automotive industry. Life Cycle assessment methodology will be used to compare the environmental impacts of this new material with traditional glass fibre composites, natural fibre reinforced composites and other materials with similar mechanical properties.

  Abstract
  With fuel economy and lightweight design becoming ever more significant due to the current materials, resources and environmental crisis, the manufacture of polymer composites [...]

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• Interface damage characterization of carbon-epoxy composite materials

  D. Mocerino, M. Bruno, M. Monclús, D. Garoz, M. Rueda, J. Molina, . M.Flores, C. Gonzalez

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 1 - Caracterización - Sostenibilidad y Reciclaje), 20

  
  

  Abstract

  This research shows a novel in-situ experimental approach to characterize a carbon-epoxy unidirectional composite system interface. Computational models were implemented to support the experimental campaign and identify the interface properties. After validating the computational model with experimental results, it was employed to study the behaviour of interface debonding under both mode I and mode II damage. By utilizing the validated model, it becomes possible to assess the consistency of the proposed experimental approach in characterizing the interface, with the aim of generating in future an analytical model able to predict interface characteristics. 

  Abstract
  This research shows a novel in-situ experimental approach to characterize a carbon-epoxy unidirectional composite system interface. Computational models were implemented to [...]

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• Sustainable synthesis of iron oxide nanoparticles embedded into carbon foams. Síntesis sostenible de espumas de carbono con nanopartículas de óxido de hierro intercaladas.

  C. Cuesta, R. García, E. Rodriguez, M. López-Antón, M. Martínez-Tarazona

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 1 - Caracterización - Sostenibilidad y Reciclaje), 21

  
  

  Abstract

    RESUMEN: Las espumas de carbono son materiales macroporosos que convenientemente funcionalizados pueden ser muy útiles en aplicaciones de adsorción y catálisis. Por otra parte, los óxidos e hidróxidos de hierro tienen excelentes propiedades para ser utilizados en biomedicina, remediación ambiental o almacenamiento de energía, entre otras aplicaciones. Este trabajo tiene como objetivo la preparación de una espuma de carbono con especies de hierro nanodispersadas en su superficie SFFe(10:1), y la identificación de los cambios sufridos en la morfología y la estructura del carbono, con respecto la espuma preparada sin especies de hierro (SF). El método de síntesis utilizado se diseñó con la intención de que fuera sencillo, necesitara un mínimo de reactivos y partiera de un precursor de carbono sostenible. Para ello, se sintetizó la espuma de carbono a partir de sacarosa en ácido cítrico, utilizando Fe(NO3)3 · 9H2O como aditivo, mediante un procedimiento basado en tratamientos térmicos en atmósferas de aire e inerte. Se observó como la adición de un 10% de nitrato de hierro al precursor favorece la espumación produciéndose simultáneamente el crecimiento in situ de nanopartículas de óxido de hierro sobre la matriz de la espuma. Además, durante la carbonización, las especies de hierro formadas catalizan una incipiente grafitización del material de carbono. Con la concentración de nitrato empleada, el hierro queda mayoritariamente como magnetita nanodispersada en la superficie de la espuma de carbono.    ABSTRACT: Carbon foams are macroporous materials that, properly functionalized, can be very useful in adsorption and catalysis applications. On the other hand, iron oxides and hydroxides have excellent properties to be used in biomedicine, environmental remediation and energy storage, among other applications. The objective of this work was the preparation of a carbon foam with nanodispersed iron species on its surface SFFe(10:1) and the identification of the changes suffered in the morphology and structure of the carbon with respect to a foam prepared without iron species (SF). The synthesis method used was designed with the intention of being simple, requiring a minimum of reagents, and starting from a sustainable carbon precursor. To this end, the carbon foam was synthesized from sucrose in citric acid, using Fe(NO3)3 · 9H2O as additive. The procedure was based on heat treatments in air and inert atmospheres. It was observed how the addition of 10% iron nitrate to the precursor favours foaming, simultaneously producing in situ growth of iron oxide nanoparticles on the foam matrix. Furthermore, during carbonization, the created iron species catalyze an incipient graphitization of the carbon material. With the nitrate concentration evaluated, the iron remains mostly as nanodispersed magnetite on the surface of the carbon foam.

  Abstract
    RESUMEN: Las espumas de carbono son materiales macroporosos que convenientemente funcionalizados pueden ser muy útiles en aplicaciones de adsorción [...]

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• Study of the recycling and reprocessing of composite materials and their subsequent use in the manufacture of sustainable composite materials

  M. Campo, I. Lorero, A. Jiménez-Suárez, S. Prolongo.

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 1 - Caracterización - Sostenibilidad y Reciclaje), 22

  
  

  Abstract

  Due to the great increase in the use of composite materials, there is a need to investigate and develop effective recovery, recycling, and reuse techniques. This technological challenge entails significant research efforts to solve the current problems to separate and reuse the components of composite materials. In this work, two alternatives have been studied to solve the environmental problems that the use of resins as a matrix of composite materials entails, since there is no sustainable recycling process after its useful life cycle. On the one hand, a thermomechanical reprocessing will be studied and on the other the viability of the chemical dissolution of the matrix. For both processes, the optimal conditions (temperature, time, solvent, and pressure) have been studied to allow reprocessing the material or dissolve the resin of the composite material to recover the fiber. Subsequently, for thermomechanical reprocessing, the technical feasibility of impregnating fibers during the reprocessing process in the hot plate press has been studied. And for chemical recycling, the feasibility that the recycled carbon fiber will be reused to make a new composite material.

  Abstract
  Due to the great increase in the use of composite materials, there is a need to investigate and develop effective recovery, recycling, and reuse techniques. This technological [...]

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• Piezoresistive sensors based on reinforced PVDF nanocomposites

  V. Díaz-Mena, X. Sánchez-Romate, D. Martinez-Diaz, M. Sanchez, A. Ureña

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 1 - Caracterización - Sostenibilidad y Reciclaje), 23

  
  

  Abstract

  Currently, due to the great advances achieved in medicine, together with those related to materials science and engineering, in recent years there has been a growing interest in the use of flexible sensors for monitoring the human body. The present work shows the development of flexible piezoresistive sensors based on polyvinylidene fluoride (PVDF) reinforced with carbon nanotubes (CNTs). First, the analysis of the electrical properties shows an increase in the electrical conductivity with CNT content. This increase is less pronounced at higher CNT contents due to an electrical network saturation, where the main electrical transport mechanisms are dominated by the CNT aggregates. In this context, the electromechanical analysis shows a higher sensitivity, by means of Gauge Factor, at lower CNT contents due to a higher prevalence of tunneling transport mechanisms between neighboring nanoparticles, which is reflected in a more exponential electromechanical behavior. Finally, the analysis of the electromechanical properties at cycling loading shows an elevated repeatability of the electrical response between consecutive cycles, which is indicative of the high robustness of the manufactured sensors.

  Abstract
  Currently, due to the great advances achieved in medicine, together with those related to materials science and engineering, in recent years there has been a growing interest [...]

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• Properties of Tetra Pak Particle Reinforced Concrete for use in masonry parts.

  D. Gámez-García, A. Alcaraz-Codina, I. Lucio-Pérez, H. Saldaña-Márquez, E. Solís, D. Martínez

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 1 - Caracterización - Sostenibilidad y Reciclaje), 24

  
  

  Abstract

  Advances in single-use packaging and container technology are generating an indiscriminate increase in urban solid waste, which is on the rise. In 2020, Mexico achieved a recycling rate of around 30% in Tetra Pak packages; although this percentage is encouraging, most waste still needs to be reincorporated into any cycle. On the other hand, one of the most alarming impacts of the construction industry is the extraction of raw materials and their potential greenhouse gas emissions. In order to associate these two environmental issues, this work aimed to evaluate the physical-mechanical properties of concrete added to Tetra Pak waste. Specimens of 10 cm in diameter and 20 cm in height were studied. For the mixtures, weight contents of 2%, 4%, 6%, and 8% of 5 mm x 3 cm fibers were used, which were tested in the fresh and hardened state at 14 and 28 days of curing. The results indicated that as the fiber content increases, the mechanical properties of the specimens decrease, so its use for structural purposes should be re-evaluated with other techniques, such as gamma irradiation. It is recommended to use this material in masonry pieces for non-structural purposes and to characterize its thermal and acoustic properties.

  Abstract
  Advances in single-use packaging and container technology are generating an indiscriminate increase in urban solid waste, which is on the rise. In 2020, Mexico achieved a [...]

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• Composite material thermal characterization for a digital twin-based model of an automated tape-laying process

  J. Rodrigues, J. Rodrigues

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 1 - Caracterización - Sostenibilidad y Reciclaje), 25

  
  

  Abstract

  As the demand of the automotive and aeronautics industry for high-performance structures increases, the tendency goes towards the use of composite materials. This tendency requires designing efficient manufacturing processes to ensure repeatability and quality. Attending those requirements, the Automated Tape Laying process has gained relevance, as an out-of-autoclave process, consuming less energy and lower production times. This process consists of continuously heating a thermoplastic-based composite material and, using a compaction roll, pressing it against a mould, consolidating the structure by cooling down the composite. On the other hand, the Automated Tape Laying process arises a relevant problem related to the control system. The problem is related to the impossibility of measuring the temperature at the nip point, the temperature under the compaction roll, having no feedback then, no control decision. To overcome this type of problem, some authors have implemented a model-based control system, which allows to estimate the temperature at the desired location. To guarantee the best estimation, the model must be as detailed as possible, which leads to the concept of a Digital Twin. The Digital Twin as a detailed mathematical representation of the physical world, requires knowing the behaviour of the process element due to their interaction. This work proposes a thermal characterization methodology, using an in-house designed method, to describe the thermal-optical and thermal-conductivity properties of composite materials as a function of their temperature, which is required for the Digital Twin to compute the temperature distribution along an Automated Tape Laying process to lower the uncertainties due to properties approximations

  Abstract
  As the demand of the automotive and aeronautics industry for high-performance structures increases, the tendency goes towards the use of composite materials. This tendency [...]

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• Estudio de procesabilidad de composite CF-LMPAEK reciclado: inyección vs impresión 3D

  C. Martín-Pérez, D. Rosario, N. González-Castro, R. Travieso-Puente, E. Rodríguez-Senín

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 1 - Caracterización - Sostenibilidad y Reciclaje), 26

  
  

  Abstract

  El proyecto ECO-CLIP se basa en una combinación de actividades de innovación orientadas a lograr piezas estructurales más ligeras a partir de los residuos de fábrica de TPC´s (Thermoplastic Composites), para la próxima generación de demostradores de fuselaje de aviación, que se lleva a cabo como parte de Clean Sky 2. En el proyecto se ha desarrollado un material polimérico compuesto de LMPAEK reforzado con un 40% en peso de fibra de carbono corta para la producción de Brackets. Con el fin de seleccionar la tecnología más ventajosa para la fabricación de estos, se ha llevado a cabo la comparativa de un método de fabricación convencional, como es la inyección, con una tecnología emergente, como es el FGF (Fused Granulated Fabrication). Para su comparativa se han llevado a cabo estudios de longitud y distribución de fibra, caracterización térmica y ensayos mecánicos, tanto para las probetas de inyección como en FGF. En esta última tecnología, además se ha llevado a cabo un estudio de parametrización de diámetros de boquillas con el fin de obtener la influencia que tiene en la adhesión entre capas, la longitud de la fibra, la microestructura de la pieza y la calidad final de las piezas. Gracias a estos resultados se ha podido establecer una relación entre la naturaleza del refuerzo, las propiedades térmicas y los parámetros de fabricación, con las propiedades mecánicas en pieza final.

  Abstract
  El proyecto ECO-CLIP se basa en una combinación de actividades de innovación orientadas a lograr piezas estructurales más ligeras a partir de los residuos [...]

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• Análisis de las propiedades mecánicas de composites de fibra continua con electrónica impresa embebida

  A. Pérez-Márquez*, J. Maudes, L. Bilbao, C. Vaquero, H. Villaverde, O. Adarraga, I. Bustero, I. Obieta, J. Gayoso

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 1 - Caracterización - Sostenibilidad y Reciclaje), 27

  
  

  Abstract

  Desde hace varios años surge la necesidad de desarrollar materiales compuestos multifuncionales, que además de las propiedades clásicas como alta resistencia y elevada rigidez, integren distintas funcionalidades como por ejemplo la capacidad de detectar cualquier deformación de la estructura o la integración de iluminación, en una tendencia hacia el aligeramiento de las estructuras. Sin embargo, en la mayoría de los casos, el hecho de embeber componentes físicos puede hacer que surjan aspectos negativos en las estructuras como la presencia de discontinuidades en la resina que son propensas a la delaminación o la iniciación de grietas alrededor del componente, disminuyendo sus propiedades estructurales. Las técnicas de fabricación, basadas en la impresión funcional para el desarrollo de circuitos y electrónica impresa como parte inherente de la estructura, son muy prometedoras y por ello, están consiguiendo una gran aceptación en el mercado. Este trabajo muestra el análisis de las propiedades mecánicas de composites de fibra continua con electrónica impresa sobre diferentes tejidos empleados en los propios procesos de fabricación como fibras de vidrio o sobre velos poliméricos fabricados a partir de la técnica de electrospinning. Los resultados obtenidos muestran que no existen diferencias relevantes en el comportamiento a tracción por el hecho de tener circuitos impresos e incluso con diferentes espesores de línea. Así mismo, el módulo de elasticidad no se ve afectado para el caso de los composites que embeban circuitos de iluminación basados en LEDs integrados sobre el velo. También se han analizado las impresiones sobre los distintos sustratos mediante microscopía y se ha medido el comportamiento de un sensor resistivo de temperatura impreso en el velo y embebido en composite, para el cual se ha conseguido una respuesta lineal con una sensibilidad de 4,9Ω/ºC.

  Abstract
  Desde hace varios años surge la necesidad de desarrollar materiales compuestos multifuncionales, que además de las propiedades clásicas como alta resistencia [...]

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• Descomposición en modos en ensayos de fractura interlaminar y de uniones adhesivas con brazos de grieta asimétricos

  F. Mujika

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 1 - Caracterización - Sostenibilidad y Reciclaje), 28

  
  

  Abstract

  Las pruebas de flexión con entalla final y viga en doble voladizo se diseñaron para caracterizar la fractura interlaminar de materiales compuestos en modos puros I y II. En ambos casos, los especímenes tienen una longitud de fisura inicial en la mitad del espesor. En el caso de especímenes bimaterial, si la grieta está ubicada en el medio del espesor, el modo mixto podría existir, debido a la asimetría material. El objetivo del presente estudio es proponer relaciones geométricas para obtener condiciones de modo puro cuando se ensayan especímenes bimateriales en configuraciones DCB y ENF.

  Abstract
  Las pruebas de flexión con entalla final y viga en doble voladizo se diseñaron para caracterizar la fractura interlaminar de materiales compuestos en modos puros [...]

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• Pruebas de fuego virtuales de paneles compuestos termoplásticos

  F. MILLAN, M. FROVEL, F. CABRERIZO, M. TORRE, . F.LOPEZ, D. BENITO, R. TEJERINA, . S.LOPEZ(‡).

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 1 - Caracterización - Sostenibilidad y Reciclaje), 30

  
  

  Abstract

  Este artículo describe el desarrollo de una metodología de simulación FEM para predecir el comportamiento de un panel compuesto con matriz termoplástica y fibras de carbono en pruebas de fuego. El panel tiene un soporte de metal en su centro a cuál se aplica simultáneamente una carga monotónica mecánica al inicio del ensayo de fuego. La herramienta tiene como objetivo capturar los fenómenos más relevantes involucrados en este complejo problema y centrarse en predecir el tiempo de desprendimiento del soporte bajo la carga aplicada, que es el resultado más relevante de dicha prueba de fuego. En el problema, muchos diferentes fenómenos físicos están involucrados. Para considerar los más relevantes, se ha seleccionado un FEM termomecánico acoplado y, dentro de él, un análisis de fluencia transitoria. Las partes más relevantes de la simulación son los supuestos del modelo térmico, el modelo constitutivo mecánico del material, la dependencia de la temperatura de las propiedades térmicas y mecánicas y la selección de un criterio de fallo consistente. Durante el desarrollo de la metodología de simulación se han tomado precauciones para identificar un conjunto de parámetros que conforman los ajustes disponibles. Seleccionando un conjunto de valores para estos parámetros, se puede simular un caso de prueba concreto. Manteniendo los valores de estos parámetros sin cambios, la metodología puede predecir casos similares en lugar de probar estos casos físicamente en ensayos de fuego. Este artículo se centra en el desarrollo de herramientas de simulación. Por el momento solo se han realizado tareas iniciales de correlación y validación. Se espera completar y mejorar esta investigación en el futuro aumentando la validez de la simulación, p.ej. incluyendo cargas de tracción y/o ángulos/distancias de llama. En el documento también se proporciona una idea de las posibles simplificaciones y mejoras de las herramientas.

  Abstract
  Este artículo describe el desarrollo de una metodología de simulación FEM para predecir el comportamiento de un panel compuesto con matriz termoplástica [...]

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• Contribution of auxetic core structures on the radial impact behaviour of 3D printed continuous fibre reinforced polyamid profiles

  U. Morales*, A. Esnaola, I. Sukia, L. Aretxabaleta, J. Aurrekoetxea

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 1 - Caracterización - Sostenibilidad y Reciclaje), 31

  
  

  Abstract

  The present study investigates the enhanced energy absorption capabilities in the radial direction of structures through the combination of continuous glass fiber reinforced polyamide hollow sections (cGF/PA) and complex cellular cores manufactured by 3D printing cFF (continuous Fibre Fabrication). For this purpose, two types of auxetic structures based on conventional reentrant structure designs (hexagonal and octagonal) have been characterised. Likewise, the energy absorption capacity (SEA) of the filled profiles has been analysed and compared with the capability of the hollow profiles. Falling weight impact tests have been carried out for the dynamic characterization of the profiles and the effect of concentric fibers and the auxetic core on filled profiles has been analysed. On the one hand, it has been identified that the octagonal re-entrant structure (RSH) presents a higher impact performance, reaching a SEA value of 8.5 kJ/kg. On the other hand, it has been found a substantial improvement in the absorption capability of the filled profiles (17.7 kJ/kg) compared to the capability of the hollow profiles (2.5 kJ/kg). The SEA values achieved are promising, as they are 18% higher than the values found in literature.

  Abstract
  The present study investigates the enhanced energy absorption capabilities in the radial direction of structures through the combination of continuous glass fiber reinforced [...]

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• Procedimiento de extrapolación de leyes cohesivas de uniones adhesivas en modo I y II: validación numérica

  A. Arrese, U. Garitaonaindia, I. Adarraga, F. Mujika

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 1 - Caracterización - Sostenibilidad y Reciclaje), 32

  
  

  Abstract

  En este trabajo se presenta y valida numéricamente un novedoso procedimiento de extrapolación para predecir las leyes cohesivas de uniones adhesivas en modo I y II. En primer lugar, partiendo de los métodos de reducción de datos basados en la variación de la flexibilidad recientemente propuestos para extraer las leyes cohesivas, se definen nuevas expresiones factorizadas con respecto a la carga aplicada y a los espesores de adhesivo y adherente de la flexibilidad (C0i), la Integral–J (J0i) y el desplazamiento de la punta de la grieta (Δ0i) para cada modo de fractura. Suponiendo que todos los efectos asociados al daño se incluyen en la longitud de grieta equivalente, y de acuerdo con las expresiones polinómicas de J0i, C0i y Δ0i con respecto a la misma, se obtienen relaciones invariantes entre J0i-C0i y Δ0i-C0i para cualquier relación de espesores adhesivo-adherente de un sistema material y configuración de ensayo determinados, tanto en modo I como en modo II. Por último, se presenta un procedimiento de extrapolación basado en las curvas calibradas J0i-C0i y Δ0i-C0i, que permite estimar las leyes cohesivas para un amplio rango de relación de espesores adhesivo-adherente de un sistema material dado procesando únicamente la curva carga-desplazamiento del ensayo.

  Abstract
  En este trabajo se presenta y valida numéricamente un novedoso procedimiento de extrapolación para predecir las leyes cohesivas de uniones adhesivas en modo [...]

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• Paneles fabricados mediante curado UV de prepregs fuera de autoclave reforzados con perfiles de pultrusión UV

  I. Eguino, G. Goenaga, A. Arruti, I. Saenz-Dominguez, I. Tena, F. Vallejo, M. Sarrionandia, J. Aurrekoetxea

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 1 - Caracterización - Sostenibilidad y Reciclaje), 29

  
  

  Abstract

  En el presente trabajo se ha demostrado el potencial de la tecnología de curado UV cuando se aplica en los materiales compuestos reforzados con fibra de vidrio. Se han comparado dos vías de fabricación de paneles; la fabricación por separado de ambos elementos y su posterior adhesivado, y la integración directa de los perfiles en el curado UV de las pieles. Los resultados de ensayos interlaminares demuestran que la resistencia de la unión prepreg/perfil es equiparable a la de la unión prepreg/prepreg. Consecuentemente, los prototipos obtenidos con ambas estrategias muestran prestaciones mecánicas similares, tanto en rigidez como en resistencia a la flexión. Por último, la baja temperatura con la que se da el curado UV de la piel permite utilizar núcleos hidrosolubles fabricados mediante impresión 3D que facilitan las operaciones de laminado y la compactación.

  Abstract
  En el presente trabajo se ha demostrado el potencial de la tecnología de curado UV cuando se aplica en los materiales compuestos reforzados con fibra de vidrio. Se [...]

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Núm. 2 - Fabricación y Aplicaciones Industriales - Sostenibilidad y Reciclaje.

• Determination of curing times in an ultraviolet curing composites manufacturing process

  J. Vallejo, I. Avila, A. Uriarte

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 2 - Fabricación y Aplicaciones Industriales - Sostenibilidad y Reciclaje.), 33

  
  

  Abstract

  Currently, the manufacture of fiberglass composite parts for the automotive industry is limited by the curing times of the resins. The curing of this type of parts is usually done at room temperature, which entails waiting times of up to 48 hours. The purpose of this study is to analyse the curing times of the pieces made with ultraviolet curing resin to replace the conventional temperature curing. In the case of ultraviolet radiation curing, the geometry of the part has a significant importance in curing times. To carry out this study, the UV lamp has been characterized to determine the irradiance at different distances. Once the irradiance is obtained as a function of the distance, the curing time of the prepreg test tubes was determined by means of a dielectric analysis (DEA). As a result, a mathematical model capable of approximating the curing time of different types of pieces based on their geometry and distance from the spotlight has been obtained. In this way, it is possible to create a strategy that optimizes the process. This process is much more efficient than the hand lay-up (HLU) used up to now, so it could be a good substitute if you want to increase the production of fiberglass composite parts.

  Abstract
  Currently, the manufacture of fiberglass composite parts for the automotive industry is limited by the curing times of the resins. The curing of this type of parts is usually [...]

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• Establishing the differences between the use of bio-based composites and nanocomposites as matrices in additive manufacturing.

  K. Nuñez-Carrero, M. Villar, L. Pastor, F. Lizalde-Arroyo, J. Pastor

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 2 - Fabricación y Aplicaciones Industriales - Sostenibilidad y Reciclaje.), 34

  
  

  Abstract

  With the recent increase in the use of additive manufacturing (AM) in more and more challenging applications, the demands on the mechanical performance and sustainability of printed parts are increasing considerably. Among the different additive manufacturing technologies, fused filament fabrication (FFF) is the most widely used for thermoplastic materials. This work focuses on comparing the behaviour of parts obtained by FFF using a bio-based polyamide (BIOPA-11) reinforced with different types of fibres: short glass fibre (GF) and a fibrillar nanoclay (SEP, sepiolite). Different composites were prepared by melt process, converted into filaments used in FFF, and characterised the final parts. The thermal and mechanical properties obtained were systematically examined as a function of printing orientation, amount and type of fibre, accompanied by X-ray tomography image analysis of the internal parts of the pieces. As expected, anisotropic properties showed improvements in Young's Modulus and tensile strength in both composites with increasing amount of reinforcement, with respect to pure biopolyamide. However, the improvements in mechanical performance of the nanocomposites were very noticeable under many conditions (composition and direction of fabrication). The research shows that this is due to the stiffening mechanism, based on the polymorphism of BIOPA, which is induced by nanometric loadings. Additionally, the internal morphology of the nanocomposite parts showed small amounts of inter-filament cavitations, while the parts obtained from the GF composites showed irregular, intra-filament cavitations. Thus, the BIOPA11 nanomaterial parts are attractive in terms of properties, weight, cost reduction, and sustainability.

  Abstract
  With the recent increase in the use of additive manufacturing (AM) in more and more challenging applications, the demands on the mechanical performance and sustainability [...]

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• Materials from revaluation of rice straw through extraction of cellulose and lignin

  V. Serrano, M. Carbonell, H. Pérez, V. Serrano Martínez

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 2 - Fabricación y Aplicaciones Industriales - Sostenibilidad y Reciclaje.), 35

  
  

  Abstract

  Rice straw is a problematic agricultural waste that is currently burnt in tonnes in the Albufera de Valencia after the harvest, with the consequent environmental damage. In this sense, to avoid wasting resources and unnecessary pollution, it is proposed to revalue the product, that is, to use rice straw, as a source of lignin and cellulose, for the development of materials for footwear, such as soles, insoles, or adhesives. The extraction of cellulose fibres from rice straw is done by physical and/or chemical processes, such as: hydrothermal steam treatment (steam explosion); alkaline treatment, peroxides, and bleaching. The extraction method is optimised by combining processes to maximise the yield obtained. To do this, the processing conditions of each of the extraction stages are varied, optimising variables such as: temperature, time, CO2 pressure, among others. Furthermore, through the use of lignin, also present in rice straw, it is possible to produce polyols to synthesise adhesives, achieving a complete revaluation of rice straw. Therefore, this study aims to determine the effect of rice straw processing conditions on the cellulose extraction yield by optimising the hydrothermal process, pre- and post-processing, as well as on the properties of the cellulose fibres, in addition to the extraction of lignin for its future use as a raw material for the production of polyols and synthesis of adhesives.

  Abstract
  Rice straw is a problematic agricultural waste that is currently burnt in tonnes in the Albufera de Valencia after the harvest, with the consequent environmental damage. In [...]

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• Diseño de moldes de materiales compuestos para la fabricación aditiva basada en extrusión

  E. Bellvert*, J. Antolín-Urbaneja, H. Vallejo, J. Gayoso, . J.I.Hernández, A. Pizarro

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 2 - Fabricación y Aplicaciones Industriales - Sostenibilidad y Reciclaje.), 36

  
  

  Abstract

  La fabricación aditiva mediante extrusión de materiales termoplásticos en formato pellet se está convirtiendo en una tecnología prometedora que trata de competir con tecnologías de fabricación convencionales. En este sentido, permite depositar una alta cantidad de material (kg/h), pudiendo generar preformas de moldes termoplásticos en un tiempo razonable que permita rivalizar con los precios del mecanizado de moldes metálicos de gran tamaño. Sin embargo, aún es necesario analizar sus limitaciones productivas, abordando soluciones desde el punto de vista de la selección de los materiales, el propio diseño del molde y los postprocesos necesarios para la obtención de moldes operativos para la fabricación de piezas con materiales compuestos. En concreto, dentro del Proyecto MOLDAM cofinanciado por el EIT Manufacturing, se ha seleccionado un material termoplástico reforzado con fibra de carbono (PA6/CF) en formato granza para la fabricación aditiva basada en extrusión de alta tasa de deposición. Se ha realizado una amplia campaña de ensayos del material extruido, para caracterizar sus propiedades termo-mecánicas en las direcciones de deposición y a diferentes temperaturas, basada en los requisitos de los casos de uso (sector aeronáutico y eólico). El objetivo ha sido desarrollar una metodología de diseño iterativo de moldes, en la que se utilizan herramientas avanzadas de Ingeniería asistida por ordenador (CAE), para simular y calcular el comportamiento termo-mecánico de los moldes mediante el análisis de elementos finitos (FEA), definiendo así los espesores y rellenos óptimos para garantizar la integridad estructural del molde en las condiciones de curado de las piezas en autoclave (P=7bar,Tª=180ºC).  

  Abstract
  La fabricación aditiva mediante extrusión de materiales termoplásticos en formato pellet se está convirtiendo en una tecnología prometedora [...]

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• Effect of the Surface treatments on the interphase during the injection moulding process with PAEK with carbon fibre

  J. Vidal, P. Castell, A. Marqués, J. Dieste

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 2 - Fabricación y Aplicaciones Industriales - Sostenibilidad y Reciclaje.), 37

  
  

  Abstract

  The transformation processes used for thermoplastic composites, have been increasing their complexity, while incorporating new high demanding materials. From the aeronautic and medical sector, with their restrictions and specific demanding needs. The PAEK materials have been promoted and deeply applied due to their high temperature stability and their chemical resistance. In this research, the work has focussed on the use of the reinforced 40%CF PEEK process through injection moulding. In these over injection moulding processes the joint between 40%CF PEEK and other materials such as Aluminium, or reinforced PA and PEEK has been studied. As well as the adhesion between them and the variation generated on the mechanical properties. It has been observed that this joint is far better between thermoplastic materials than between metals and thermoplastic, this is due to the fact that even tough the PEEK has high processing temperatures, these are not relevant chemically speaking for metals such as Aluminium. Limiting the forces of the interphase to the physical and mechanical interaction between both materials. Nevertheless, in the case of the thermoplastic over injected parts several parameters have been observed to be affecting the final properties of the joint. Firstly, the over injected angle, obtaining higher mechanical properties as the angle increases as well as the contact surface. And the effect of the roughness of the overinjected part, having these a direct impact on the final mechanical properties.

  Abstract
  The transformation processes used for thermoplastic composites, have been increasing their complexity, while incorporating new high demanding materials. From the aeronautic [...]

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• Implementation guidelines for the application of innovative composite manufacturing processes in the shipbuilding industry

  I. Saenz-Dominguez, R. Pereira, I. Ruiz de Eguino, A. Arruti, I. Tena

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 2 - Fabricación y Aplicaciones Industriales - Sostenibilidad y Reciclaje.), 38

  
  

  Abstract

  Composites are still playing an important role in the strategic agendas of industries associated with the transport sector, such as the shipbuilding industry. This is mainly because composites are a key element in lightening structures due to their elevated strength-to-weight characteristics, excellent corrosion resistance and low maintenance costs. However, the production capacity in the number of Fibre Reinforced Polymer (FRP) ships nowadays is not achieving its full potential due to high total production costs. Thus, to maintain or even expand the competitive position of the EU shipbuilding industry it is essential to improve, optimize and automate the production processes for FRP parts. The European Project Fibre4Yards (This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101006860) addresses this challenge through the implementation of the Shipyard 4.0 concept and applying innovative FRP manufacturing technologies to the shipbuilding industry such as: curved pultruded profiles, automated fibre placement (ATP), adaptive moulds, additive manufacturing, and hot stamping. This work proves that during the adaptation process of certain manufacturing technologies to a new market, the decision-making stage must follow some specific steps: from the first analysis of the technical feasibility and the perception of the market of each technology, to the final measurements of the achieved improvements. Therefore, in this paper, implementation guidelines on adapting new composite manufacturing processes to the shipbuilding industry are presented, based on their evolution from the initial state to the final improvements.

  Abstract
  Composites are still playing an important role in the strategic agendas of industries associated with the transport sector, such as the shipbuilding industry. This is mainly [...]

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• Re-usage of uncured carbon fiber scrap material

  J. Sistach*, A. Calero, B. López-Romano, M. Ordóñez

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 2 - Fabricación y Aplicaciones Industriales - Sostenibilidad y Reciclaje.), 39

  
  

  Abstract

  Industrial automated tape layup methods significantly increase the productivity, precision, and efficiency of manufacturing methods for large aerospace parts; however, although they allow reducing scrap fraction compared with manual processes, it keeps being too high, requiring waste management. The scope of the MC4 project, part of Horizon Europe program, is to not only recycle that scrap material, but also to transform it to a completely new, functional part, without the need of adding additional material other than this recycled scrap. This can be achieved by cutting that material into strip shape and reducing it to a specific thickness by means of a compacting process. Those homogenous thickness strips can then be processed using a heated plate press to form it to any needed shape. Mechanical properties will be studied and compared to the original material, to check if this process is suitable for the manufacturing of functional parts. As this method does not separate the original resin and fiber, it avoids the usage of chemicals that can damage the properties of the material and increase the risk and pollution of the process, which is ideal for a recycling process.

  Abstract
  Industrial automated tape layup methods significantly increase the productivity, precision, and efficiency of manufacturing methods for large aerospace parts; however, although [...]

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• Revaluation of recycled reinforcement fibers through innovative textile technologies for developing new thermoplastic composites

  I. Doménech, J. Pascual, F. Fornés, C. Santamaría

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 2 - Fabricación y Aplicaciones Industriales - Sostenibilidad y Reciclaje.), 40

  
  

  Abstract

  Composite materials, such as those made from carbon and glass fibres, are now considered to be high value-added materials. However, a barrier to their full circularity is the difficulty of their recyclability and the serious environmental problems that these materials pose. Fibres can be recovered using techniques such as pyrolysis and solvolysis and disposed of as chopped fibre at the end of their life cycle. However, their use in industrial applications is limited to injection moulding, anisotropic mats, etc. This work has focused on the research and adaptation of textile technologies for staple fibre processing, such as carding, spinning and weaving, with the aim of obtaining textile intermediates suitable for the production of thermoplastic composites. These technologies must improve the mechanical properties of currently available commercial solutions and adapt to these reinforcing fibres, which are fragile, extremely thin and in some cases electrically conductive. This research has resulted in the production of intermediate textile products such as hybrid yarns (rCF-PA6 and rAramid-PA6), and nonwovens (rCF-PA6, rAramid-PA6 y rGF-PA6), both suitable for obtaining mainly thermoplastic composites.

  Abstract
  Composite materials, such as those made from carbon and glass fibres, are now considered to be high value-added materials. However, a barrier to their full circularity is [...]

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• Modification of the performance of printed parts through their hybridization with thermostable resin

  J. Gómez, S. Neira, A. Allue, K. Gondra, D. Pineda

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 2 - Fabricación y Aplicaciones Industriales - Sostenibilidad y Reciclaje.), 41

  
  

  Abstract

  The final benefits obtained in plastic parts made with the commonly used 3D printing technologies (extrusion, laser sintering, photopolymerizable resin bath, inkjet) depend on the nature of the materials used, and the variables and printing strategies followed for obtaining the parts. In the present study, working with filament extrusion technology, the development of hybrid polymeric structures has been analysed with the purpose of being used as moulds for plastic and composite moulding processes. 3D printing by thermoplastic extrusion enables the use of a wide catalogue of materials, and facilitates the hybridization of the printed parts, choosing different values for variables such as skin thickness, wall thickness, or the pattern and infill percentage. Acting on the values of these variables, it is possible to generate superficial and internal porosity, or obtain cast parts with solid walls that define the geometric details and the surface finish of the final part. The hybridization study was carried out with PC ABS as a thermoplastic printing matrix and catalysed thermosetting resin as a complementary material. The characteristics of the thermosetting resin used in hybridization can be modulated by formulating its composition, to achieve additional features or functionalities in the printed parts, such as greater thermal or mechanical resistance, to modify their conductivity or thermal or electric insulation characteristics.

  Abstract
  The final benefits obtained in plastic parts made with the commonly used 3D printing technologies (extrusion, laser sintering, photopolymerizable resin bath, inkjet) depend [...]

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• Integrated nano-enabled heaters for automotive composite panels to enable external airbag activation

  R. Seddon, M. Chapartegui, I. Gaztelumendi, A. Iriarte Legarreta, S. Florez, N. Romero, R. Fernandez

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 2 - Fabricación y Aplicaciones Industriales - Sostenibilidad y Reciclaje.), 42

  
  

  Abstract

  OASIS Composites Open Innovation Test Bed (OITB) is a single-entry point for scale-up of Innovative Smart lightweight polymer matrix and aluminium composite materials and components. OASIS offers technological and business support services for accelerated innovation studies and success in industrialisation, market penetration and commercialisation of nano-enabled products (NEPs). IGESTEK (Spain) is a leading company in the development of technology projects: specialized in lightweight solutions using plastics and composite materials. In collaboration with Tecnalia (Spain), IPC (France), University of Patras (Greece), UCLM (Spain), TMBK (Poland) and AMIRES (Czech Republic) they identified an opportunity for the development of a heating system based on buckypapers (MWCNT films) for automotive exterior bodywork panels manufactured using recyclable thermoplastic composite material via a press moulding method. Heater integration was screened using resistive heating, simple mechanical and microscopy analysis of the test panels. Coupon panels were manufactured (using optimised processing conditions) for thermal analysis. A prototype mould was designed and manufactured for the fabrication of representative demonstrator parts (1:3 scale car bonnet panel). Electrothermal analyses of four heater configurations were calculated, leading to the selection of two final demonstrator configurations. Ten functioning demonstrator panels were successfully manufactured based on these two designs. Thermal assessment of the integrity of the heaters was carried out via electrical resistive heating. The results of the collaboration confirmed that NEP based thin film heaters could successfully be integrated into thermoplastic composite panels via a compression thermoforming process.

  Abstract
  OASIS Composites Open Innovation Test Bed (OITB) is a single-entry point for scale-up of Innovative Smart lightweight polymer matrix and aluminium composite materials and [...]

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• Infinite: composites aeroespaciales sensorizados digitalmente desde su fabricación hasta el final de vida

  A. Uriarte

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 2 - Fabricación y Aplicaciones Industriales - Sostenibilidad y Reciclaje.), 43

  
  

  Abstract

  Uno de los mayores desafíos a los que se enfrenta la industria aeronáutica europea es la necesidad de ofrecer tecnologías digitales transformadoras para completar el ciclo de vida de las aeronaves y aumentar la competitividad. Esto ha llevado recientemente, por ejemplo, al desarrollo de nuevas superficies aerodinámicas, SHM y la incorporación de materiales multifuncionales tanto dentro de estructuras primarias como secundarias, entre otros. Sin embargo, es necesario incorporar las ventajas de los sistemas de control inteligentes que se pueden utilizar para la monitoración in situ de la fabricación de alto valor, el mantenimiento, reparación y revisión (MRO) en servicio y el reciclaje al final de la vida útil (EoL).El proyecto europeo INFINITE tiene como objetivo desarrollar sensores y analizadores basados en el uso de microhilos ferromagnéticos para ser embebidos en piezas estructurales compuestas, con el fin de monitorizar la fabricación y la salud estructural a lo largo de todo el ciclo de vida del componente. El sistema de monitoreo inalámbrico permitirá producir señales digitales y gran conjunto de datos vinculados con el espécimen para crear un gemelo digital de la estructura construida que también representará toda la historia desde que se fabricó a través de todas las operaciones de mantenimiento realizadas. Esto proporcionará los medios para desarrollar una garantía de calidad precisa, rentable y personalizada de los componentes compuestos aeroespaciales a lo largo de toda su vida útil, asegurando que las estructuras aeroespaciales estén bien posicionadas para cumplir con las estrategias económicas circulares actuales, pero altamente exigentes.

  Abstract
  Uno de los mayores desafíos a los que se enfrenta la industria aeronáutica europea es la necesidad de ofrecer tecnologías digitales transformadoras para [...]

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• Design and manufacture of 3D printed cores for the integration of photovoltaic cells in sandwich panels

  I. Sukia, A. Esnaola, J. Aizpurua, W. Cambarau, J. Hernández, J. Aurrekoetxea

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 2 - Fabricación y Aplicaciones Industriales - Sostenibilidad y Reciclaje.), 44

  
  

  Abstract

  Multifunctional sandwich panels that can lighten and generate electrical energy are strategic for many industrial sectors, such as electric vehicle roofs or drones. This work analyses the integration of crystalline silicon photovoltaic cells between the glass/epoxy skins and the core manufactured by 3D printing with a polyamide reinforced with short carbon fibres. 3D printing has enabled the development of lightweight and stiff cores, with integrated wiring and junction box housings within the sandwich structure, as well as facilitators for the skin infusion process. The core design, with ramps on the periphery, facilitates the lamination and impregnation flow in the infusion process and the re-coating operations after infusion. The results, comparing the performance of the sandwich panel with and without integrated photovoltaic cells, show that the effect on the mechanical properties of the sandwich panel is not very significant. The maximum force recorded under a complex bending-twisting load is 11% lower with cells, but no delamination phenomena were observed in any case. As for the penetration energies under quasi-static and impact loads, the energies recorded for structures with photovoltaic cells are 5% and 2% lower respectively.

  Abstract
  Multifunctional sandwich panels that can lighten and generate electrical energy are strategic for many industrial sectors, such as electric vehicle roofs or drones. This work [...]

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• Mechanical recycling of composites for profile production by pultrusion

  S. Quiles-Díaz*, A. Gálvez Moreno, E. Barriguete, M. Hernández, A. Menaza, A. Farre.

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 2 - Fabricación y Aplicaciones Industriales - Sostenibilidad y Reciclaje.), 45

  
  

  Abstract

  The investigation into recycling methodologies for composite materials has emerged as a prominent area of study, encompassing both theoretical research and practical implementation. Within this context, the present study focuses on the mechanical recycling of obsolete epoxy resin pieces reinforced with fiberglass, which are subsequently repurposed as fillers in the production of new profiles through pultrusion technology. A comprehensive examination of the grinding process, granulometric distribution, and rheological properties of the final system was conducted, with the objective of maximizing the filler content within the resin while optimizing the properties of the manufactured profile. Consequently, a flat profile measuring 10 cm in width was successfully fabricated, which incorporates the recycled filler comprising up to 30 % of the resin’s total weight. This achievement was realized by employing a pultrusion system measuring 25 meters in length, coupled with a heated flat plate mold spanning 80 cm. Following the fabrication of the profile, an extensive characterization of both its physicochemical properties and mechanical behavior was conducted to investigate the influence of filler on the ultimate product. The outcomes obtained demonstrate compelling evidence that the incorporation of the recovered filler effectively enhances the interlaminar properties of the pultruded composite materials, thereby underscoring the inherent potential of the charge as a reinforcing agent.

  Abstract
  The investigation into recycling methodologies for composite materials has emerged as a prominent area of study, encompassing both theoretical research and practical implementation. [...]

  • 39
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• Automated recycling of unidirectional preimpregnated carbon fibre scraps

  T. Gonzalo, J. Seara, G. Aizpurua, K. Garmendia, J. González, J. Pozo

  Materiales Compuestos (2023). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 2 - Fabricación y Aplicaciones Industriales - Sostenibilidad y Reciclaje.), 46

  
  

  Abstract

  It is estimated that the aeronautic industry in the European Union produces annually around 10 tn of uncured prepreg scraps, generated mainly from manual and automated lamination processes of composites, and that the treatment cost for these residues is between 3 and 12 € per kilogram. This work presents a technology for the reuse of the unidirectional prepreg scrap using a machine that allows the manufacturing companies, mainly form aeronautic sector, the reuse and valorisation of the leftovers of PREPREG in the workshop, involving a reduction in the economic and environmental impact. The developed solution consists in a machine able to perform the needed processes to reuse the prepreg scrap leftovers in an automatic and efficient way, maintaining the quality and the material properties for the manufacturing of non-critical components. The equipment integrates different technologies that include computer vision to identify the shape of the leftovers and the fibre direction, cutting technology to generate regular rectangular chips aligned with the fibre direction, and a robotic system to pick and place the chips generating an ordered pattern. The result of the process is a material sheet aiming to control the mechanical properties by using homogeneous chips with controlled fibre orientation following a predefined pattern.

  Abstract
  It is estimated that the aeronautic industry in the European Union produces annually around 10 tn of uncured prepreg scraps, generated mainly from manual and automated lamination [...]

  • 37
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Núm. 3 - Caracterización - Daño, Fractura y Fatiga

• Analysis of the pure shear stress-strain state obtained by biaxial tension-compression test

  S. Horta Muñoz, M. Serna Moreno

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 3 - Caracterización - Daño, Fractura y Fatiga), 1

  
  

  Abstract

  Characterization of shear properties in unidirectional fibre composite materials can be a complex process due to the difficulty in obtaining uniform and pure shear stress-strain states at the moment of failure. This limits the range of application of the most commonly used standardized methods, as they focus on small deformations. Therefore, this work proposes an alternative solution: the tension-compression test applied to cruciform specimens with ±45° symmetric laminates for the characterization of lamina in-plane shear properties. By using a test method that provides uniform and pure shear stress-strain states, the accuracy of the results can be improved, and the range of application of the method can be expanded. The analysis is based on experimental tests, supported by simulations performed using the finite element method. Special attention is paid to verifying the achieved shear state, and the obtained response is compared with standardized tests that generate non-pure shear stress-strain states on the principal material directions. Additionally, Digital Image Correlation is used during the test to verify the appearance of nonlinear response in different regions of the cruciform specimen, which allows ensuring the validity of the test.

  Abstract
  Characterization of shear properties in unidirectional fibre composite materials can be a complex process due to the difficulty in obtaining uniform and pure shear stress-strain [...]

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• Analytical approach for two-plane bending applied to unidirectional composite plates

  U. Garitaonaindia, N. Carbajal, M. Isasa, F. Mujika

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 3 - Caracterización - Daño, Fractura y Fatiga), 2

  
  

  Abstract

  In this work, a new analytical procedure is developed to obtain the displacement field of a unidirectional composite plate subjected to bending in two planes. The analysed configuration consists of a plane plate supported at four points to which a point force is applied at the centre. The calculation procedure is based on the strain energy. The effects created by bending moments, torsional moments and shear forces in the plate have been considered. The results obtained analytically have been validated by comparing them with existing literature and with numerical simulations performed with the finite element software ABAQUS. High correlations have been obtained for the values corresponding to the vertical displacements in different alignments of points belonging to the plate, however, the same has not occurred with the distribution of moments.

  Abstract
  In this work, a new analytical procedure is developed to obtain the displacement field of a unidirectional composite plate subjected to bending in two planes. The analysed [...]

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• Energy absorption capacity of pre-homologated polyamides against fire for 3D-printing

  U. Morales, A. Esnaola, I. Sukia, U. Olaziregi Cuevas, J. Aurrekoetxea

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 3 - Caracterización - Daño, Fractura y Fatiga), 3

  
  

  Abstract

  Recent advances in developing new concepts for railway structures demand new lightweight structure concepts not only to reduce their energy consumption but also to reduce the load transmitted to the rail track. Fibre-reinforced polymers (FRP) have gained attention in the railway industry due to their lightweight properties, specific strength and stiffness, and corrosion resistance. Most published studies on the design of lightweight structures, for body and rolling stock, focus on continuous fibre-reinforced thermoset polymers (cFRP). However, derailment risk and fire safety must never be compromised due to this weight-reduction process.   Therefore, new structure designs must be impact resistant and the materials must comply with EN-45545-2. A wide variety of fire protection, self-extinguishing or flame retardant systems for composite components and structures are available in the literature. The influence of flame retardant loading on the impact properties of a continuous carbon fibre reinforced polyamide 6 manufactured by 3D printing of continuous carbon fibre prepregs (FFF) has been analysed in the present work. The impact characterisation of a sandwich panel with a bio-inspired cellular core was carried out in this study. From the results, it has been concluded that the pre-homologated materials (Onyx-FR and cCF/PA-FR) have a similar energy absorption capacity (EAS) to that of the reference reinforced polyamide 6 used in 3D printing processes - FFF.

  Abstract
  Recent advances in developing new concepts for railway structures demand new lightweight structure concepts not only to reduce their energy consumption but also to reduce [...]

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• Characterization of induction welded thermoplastic composites

  J. Sogorb, N. Sarin, C. Worrall, J. Wächter, S. Gonzalez, R. Buelga, F. Lasagni

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 3 - Caracterización - Daño, Fractura y Fatiga), 4

  
  

  Abstract

  Rib-AM project aims to contribute to the development of novel in-situ manufacturing technologies applied to large size components of primary structure of aircrafts. Framed in Clean Sky 2, the activities within Rib-AM are set out to develop a leading-edge (LE) concept based on reinforced thermoplastic materials avoiding mechanical joints between the skin and the ribs. Induction Welding (IW) process has been selected for the integration of the ribs into the leading-edge structure. The development of an appropriate IW process methodology, including the introduction of magnetic flux concentrators and new coil designs, are key to assure the quality and structural integrity of the produced joints. In this research, the mechanical strength of induction welded thermoplastic composites have been evaluated at sample level. Characterization specimens have been obtained by welding: (i) short carbon fiber reinforced polyether ether ketone (SCFR/PEEK), with 10 % carbon content, processed by additive manufacturing – fused deposition modeling; and (ii) multidirectional carbon fiber reinforced polyether ether ketone (CFR/PEEK) laminates processed by oven consolidation. The mechanical characterization of the strength has been carried out by means of the block shear test method. In addition, light optical microscopy has been performed to analyse the SCFR/PEEK - CFR/PEEK interface. Infrared thermography (IRT) has been considered for the non-destructive characterization of the welded joints to evaluate the feasibility of being applied as an inspection method for induction welded structures. IRT results have been validated by X-ray computed tomography.

  Abstract
  Rib-AM project aims to contribute to the development of novel in-situ manufacturing technologies applied to large size components of primary structure of aircrafts. Framed [...]

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• New analytical models for non-symmetric Double Cantilever Beam and End-Notched Flexure tests

  F. Mujika, A. Arrese, J. Gracia, A. Boyano

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 3 - Caracterización - Daño, Fractura y Fatiga), 5

  
  

  Abstract

  The fundamentals of new analytical models based on energy and coenergy of deformation are explained to analytically address asymmetric interlaminar fracture tests. After reviewing some concepts of laminated beam theory, the energy release rate as a function of coenergy is determined from a global point of view, including in an unprecedented way the contribution of hygrothermal stresses. On the other hand, after the determination of the J integral in the cohesive zone, the conditions required for the asymmetric fracture tests to occur in pure mode in linear elastic fracture are explained, based on the forces and displacements of the crack tip. Furthermore, knowing these forces and displacements, it is possible to determine the energy release rate that corresponds to each fracture mode.

  Abstract
  The fundamentals of new analytical models based on energy and coenergy of deformation are explained to analytically address asymmetric interlaminar fracture tests. After reviewing [...]

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• Use of digital image correlation to quantify the different fracture modes in the Longitudinal Half Fixed Beam (LHFB) test

  M. Lozano, A. López, A. Argüelles, J. Viña, P. Vigón

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 3 - Caracterización - Daño, Fractura y Fatiga), 6

  
  

  Abstract

  One of the failures with significant practical repercussions in structural elements made of laminated composite materials is the formation and growth of interlaminar cracks (delamination) under static and dynamic loading. Although the cracks can be subjected to three different modes of stress, the material toughness in mode III is higher than in the other two, so delamination mainly occurs in modes I or II. This is true when there is more than one fracture mode acting in the element. However, by using a testing methodology that allows testing in pure or nearly pure mode III, such as the Longitudinal Half Fixed Beam (LHFB) method, it is possible to characterize the material against this mode. Therefore, the degree of purity of mode III, compared to the residual modes I and II, will be an important indicator of the adequacy of the testing methodology. In this research work, the degree of purity of mode III in LHFB-type tests has been determined by using a digital image correlation (DIC) system. This technique allowed for the analysis of displacements in the X, Y, and Z directions in specimens with initial crack lengths of 1, 5, 10, 15, 20, 25, and 30 mm, using AS4/8552 and AS4/3501-6 materials. Considering the displacements measured with DIC during the different tests, it has been possible to determine the level of combination of modes I, II, and III achieved during the tests.

  Abstract
  One of the failures with significant practical repercussions in structural elements made of laminated composite materials is the formation and growth of interlaminar cracks [...]

  • 0
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• Analysis of multiple high-velocity impact phenomenon in composite laminate plates

  M. Paredes-Gordillo, I. Iváñez, S. García-Castillo, C. Navarro

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 3 - Caracterización - Daño, Fractura y Fatiga), 7

  
  

  Abstract

  High-velocity impact is one of the most common load states to which composite material structures can be subjected during their service life and can cause a sudden loss of properties favouring its catastrophic failure. Impact loads are usually caused by external elements such as debris, particles carried by the wind, hail, fragments derived from an explosion, etc. All these cases can be represented as high-velocity impacts; however, in general, these impacts are not usually reduced to the action of a single projectile on the structure but can be represented as multiple projectiles that impact simultaneously, or sequentially, on it. This is known as multiple impact phenomenon. In this work a numerical model is developed, using a commercial finite-element software, that allows to analyse the phenomenon of multiple impact in composite material laminates, focusing attention on the wave’s interaction between projectiles. The model is validated with experimental results from the scientific literature for a single high-velocity impact. The interaction among waves generated by the action of two projectiles impacting at the same velocity, and that are separated at a certain distance from each other (simultaneous high-velocity multiple impact), is studied in terms of out-of-plane displacement, and relative movement between projectiles.

  Abstract
  High-velocity impact is one of the most common load states to which composite material structures can be subjected during their service life and can cause a sudden loss of [...]

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• Experimental study of the use of ultra-thin plies in quasi-isotropic laminates under cyclic tension after impact

  C. Sandino, S. Sánchez Carmona, E. Correa Montoto, F. Paris

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 3 - Caracterización - Daño, Fractura y Fatiga), 8

  
  

  Abstract

  In this work, the authors propose an experimental study on the possible improvement of the mechanical behaviour produced by ultra-thin plies in laminates subjected to cyclic loading after impact. More specifically, this work introduces the use of these plies in carbon fibre quasi-isotropic laminates, with the aim of studying the evolution of impact damage under tensile cyclic loads. To this aim, the behaviour of quasi-isotropic laminates consisting of conventional thickness plies is compared with laminates with 90° ultra-thin plies, keeping the same stacking sequence. When considering the same loading level, the damage evolution shows a lower progress and a later failure for the laminates containing ultra-thin plies.

  Abstract
  In this work, the authors propose an experimental study on the possible improvement of the mechanical behaviour produced by ultra-thin plies in laminates subjected to cyclic [...]

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• Characterisation of the mode I interlaminar fracture toughness in multidirectional interfaces in a 3D-printed composite

  J. Santos, N. Blanco, J. Guerrero

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 3 - Caracterización - Daño, Fractura y Fatiga), 9

  
  

  Abstract

  Debonding between plies, or delamination, is a critical failure mechanism for laminated composite materials and has been analysed in several scientific investigation. Usually in real applications delamination initiates and propagates between interface layers with different reinforcement orientation. However, most of the experimental works are carried out using unidirectional specimens for determining the interlaminar fracture toughness because in laboratory conditions it is difficult to propagate the crack between multidirectional interface layers without other failure mechanisms that invalidate the test. Among these failure mechanisms, crack plane migration and crack branching at several planes are the most common. In this communication it will be detailed and analyzed the experimental characterization of the interlaminar fracture toughness in multidirectional interfaces of 3D-printed composite materials is detailed, including the manufacturing process of the Double Cantilever Beam (DCB) specimens that warranty crack propagation under pure mode I loading and without plane migration. Finally, a quantitative comparison is carried out between multidirectional interlaminar fracture toughness and the unidirectional one and a fractography analysis is reported.

  Abstract
  Debonding between plies, or delamination, is a critical failure mechanism for laminated composite materials and has been analysed in several scientific investigation. Usually [...]

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• Behaviour of fibre/matrix interface cracks under biaxial stress state caused by edge effect in carbon/epoxy laminates

  S. Sánchez Carmona, C. Sandino, E. Correa Montoto, A. Barroso, F. Paris

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 3 - Caracterización - Daño, Fractura y Fatiga), 10

  
  

  Abstract

  A recent study about the ''edge effect'' phenomenon in cross-ply laminates made of ultra-thin plies composites has shown the presence of a relevant stress component through the laminate thickness. This fact implies that there is a biaxial stress state in the 90° ply block, which is present both before and after the cyclic loading tests. 4 cross-ply laminates were analysed, only varying the 90° ply block thickness. In each case, the biaxial stress state was obtained, selecting the most detrimental one to analyse the Energy Release Rate (G) with respect to the fibre/matrix interface crack growth. This analysis is performed using a BEM model from a previous study of the authors. An exhaustive microscopic revision is performed both before (only sanded and polished after curing process) and after cyclic testing, corroborating the occurrence of different crack growth of the present longitudinal fibre/matrix interface debonds. In conclusion, the single fibre numerical model using BEM and the experimental microscopic observations shed light on the micromechanical behaviour of the interface cracks which are subjected to a biaxial stress state.

  Abstract
  A recent study about the ''edge effect'' phenomenon in cross-ply laminates made of ultra-thin plies composites has shown the presence of a relevant stress [...]

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• Study of the influence of stacking sequence in the failure of cross-ply laminates manufactured with ultra-thin plies

  M. Velasco*, E. Correa, S. Sánchez-Carmona, F. Paris

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 3 - Caracterización - Daño, Fractura y Fatiga), 11

  
  

  Abstract

  Numerous studies on the use of laminates manufactured with ultra-thin composite laminates have shown the existence of a significant delay in the appearance of damage, a phenomenon known as the Scale Effect. To study the effect that layer thickness may have on the damage mechanisms that appear at higher values of the load, this work analyses whether the use of ultra-thin laminates exhibits a better behaviour in the instants prior to failure and laminate rupture. For this purpose, different laminates have been manufactured with ultrathin thickness material formed by the same number of laminae oriented at 0 and 90 degrees, but with different stacking sequences, distributing the laminae such that the thicknesses of the resulting layers are different. The laminates have been subjected to uniaxial tension up to values close to the ultimate load in order to observe and compare the different damage morphologies that appear in the 90 and 0 degrees layers, using optical microscopy techniques for the observation of the damage. On the other hand, the loads for which the failure of the selected laminates happens have also been compared. The results obtained from this study show different behaviour of the laminates depending on the thickness of their 0 and 90 degrees layers in the moments prior to failure and at the instant when failure occurs.

  Abstract
  Numerous studies on the use of laminates manufactured with ultra-thin composite laminates have shown the existence of a significant delay in the appearance of damage, a phenomenon [...]

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• Study of delamination behavior in adhesive joints with epoxy-based adhesive under Mode II

  P. Vigón, A. Argüelles, I. Viña, M. Lozano, J. Viña

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 3 - Caracterización - Daño, Fractura y Fatiga), 12

  
  

  Abstract

  This study experimentally analyses the phenomenon of delamination under static and fatigue loading in mode II using the standardized End-Notched Flexure (ENF) test. Adhesive joints made of two epoxy matrix laminates reinforced with unidirectional carbon fiber are studied, bonded with an epoxy adhesive, and subjected to environmental degradation in a saline environment for exposure periods of 1, 2, 4, and 12 weeks. By conducting initial static tests on the joints, we identified crucial values for the rate at which energy is released under mode II conditions. These values served as a benchmark to establish the approach for dynamic fatigue testing. Our objective was to generate characteristic curves that illustrate how these adhesive joints behave when fatigue delamination begins, while also assessing the impact of varying exposure periods on their performance. To enhance result interpretation, we employed a probabilistic model rooted in the Weibull distribution to analyse the experimental data. The results show that adhesive joints experience a decrease in their delamination resistance when exposed to a saline environment.

  Abstract
  This study experimentally analyses the phenomenon of delamination under static and fatigue loading in mode II using the standardized End-Notched Flexure (ENF) test. Adhesive [...]

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• Thermoplastic weld fatigue behaviour analysis using structural health monitoring sensors data

  M. Mazzeschi, K. Nuñez-Carrero, M. Fernandez, E. Cañibano, J. Merino

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 3 - Caracterización - Daño, Fractura y Fatiga), 13

  
  

  Abstract

  Thermoplastic composite joints show many advantages in comparison to conventional fasteners. However, thermoplastic welding of primary aircraft structures is still a certification issue. Long and extensive fatigue and test campaign is required for a depth understanding of damage progression. In fact, scarce historical data are currently available and the joint fatigue performances are extremely sensitive to numerous welding process parameters. In this context, Structural Health Monitoring (SHM) technologies consists of a built-in sensors network providing real-time condition and the damage state of a structure. SHM brings several benefits. First of all, SHM ensures safety in-flight through continuously assessing damages and alerting if strength reduction approaches acceptable limits. The data obtained are useful for future structure retrofitting and new developments. Moreover, SHM has the potential to support and speed up the certification of thermoplastic composite joint. SHM data give added value to each individual fatigue test contributing to a greater understanding of damage progression and making fatigue campaign shorter and more efficient. In the present work, both quasi-static as well as fatigue tests were conducted to evaluate performances of thermoplastic induction welded joints. Strain gauges and purpose-designed electromagnetic-based SHM sensor were integrated into the specimens in order to collect useful data during tests in three main cases: lap-joint specimens manufactured (i), (ii) with two different set of process parameters and (iii) with an artificially generated lack of weld at the joint interface. The approach proposed and data collected by the sensors has provided valuable information for understanding damage propagation in this kind of joint.

  Abstract
  Thermoplastic composite joints show many advantages in comparison to conventional fasteners. However, thermoplastic welding of primary aircraft structures is still a certification [...]

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• Resistance welding of thermoplastic composite: from laboratory optimization to scale-up on a fuselage demonstrator

  S. Pintos, N. González-Castro, M. Russello, J. Illade-Quinteiro, I. Monzón, G. Herranz

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 3 - Caracterización - Daño, Fractura y Fatiga), 30

  
  

  Abstract

  Future aircraft manufacturing factories are moving towards more flexible and adaptable manufacturing systems that enable shorter manufacturing cycles, environmental friendliness, energy efficiency, and higher productivity. A global aeronautic trend to face this challenge includes the replacement of metal parts with composite counterparts with emphasis on thermoplastic composites (TPCs) for their unique ability to be recycled, reprocessed, and welded. Aiming to commit to the drastic projected increase in aircraft production rates, WELDER project, focused on the next-generation MultiFunctional Fuselage Demonstrator (MFFD), has promoted the development and investigation of highly integrated and robotized manufacturing technologies that needed to be scaled up from a laboratory to an industrial environment. To contribute to such an advance, resistance welding was investigated in this work and successfully automatized for fuselage components assembly. Welding investigation, including process maturation, parameter optimization, and scale-up analysis was performed at laboratory using LM-PAEK/CF composites. A resistance welding Heating Element (HE), made of stainless steel metal mesh and embedded in glass fiber scrims, was first designed and manufactured using a hot press. The HE, priorly characterized by electrical analysis, was adopted, in conjunction with a lab-scale welding head, to optimize and define appropriate processing times (welding and cooling), welding power, and pressures for the welding of the composite parts. The welds were characterized by visual inspection, microscopy analysis, and mechanical tests (SLSS tests - AITM 1-0019). Once materials and processes were optimized, they were scaled up to finally perform the welding of the frame couplings into MFFD.

  Abstract
  Future aircraft manufacturing factories are moving towards more flexible and adaptable manufacturing systems that enable shorter manufacturing cycles, environmental friendliness, [...]

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Núm. 4 - Sostenibilidad y Reciclaje

• Life cycle assessment of new Talgo lightweight prototypes

  . M.Cerdeira*, E. Guerra, F. García, J. Fernández, . V.Meroño

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 4 - Sostenibilidad y Reciclaje), 14

  
  

  Abstract

  The European rail network is largely electrified, and rail emits far less CO2 than equivalent travel by road or air. It accounts for only 0.4 % greenhouse gas emissions from EU transport, while all EU transport accounts for 25% of the EU’s total emissions. Additionally, rail is the only transport that between 1990 and 2017 has consistently reduced its emissions and energy consumption, while increasingly using renewable energy sources. Following this green line, this article presents the Life Cycle Assessment (LCA) study of new generation trains, mainly based on lightweighted primary structures made of composite material (about 30-50% weight loss compared to conventional ones). The composite materials are novelty in the railway sector. Their introduction brings a clear advantage from the point of view of train capacity or energy/infrastructure canon savings. However, it needs to be justified from the LCA point of view. Two different stages are developed in this article. An LCA of the new prototypes (production, assembly, transport and use phase). It is completed with an LCA of conventional structures. The second phase presents a comparison between the environmental impact produce using CFRP materials or metallic materials at the end of a useful life (EoL) of a carbody. The results indicates that, at EoL, the composite material would be more economically and environmentally attractive than the current materials.

  Abstract
  The European rail network is largely electrified, and rail emits far less CO2 than equivalent travel by road or air. It accounts for only 0.4 % greenhouse gas emissions from [...]

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• Bio-based recyclable crosslinked polyurethanes based on a thermally reversible Diels-Alder adduct

  A. Restrepo Montoya, I. Larraza, K. Gonzalez, O. Echeverria Altuna, I. Harismendy, A. Saralegi, A. Eceiza

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 4 - Sostenibilidad y Reciclaje), 15

  
  

  Abstract

  Thermosets comprise a family of chemically cross-linked networks formed by irreversible chemical reactions, resulting in polymers with outstanding properties such as superior mechanical properties, high thermal stability and chemical resistance. However, their high stability precludes reprocessing or recycling, thus making it difficult to move towards a circular economy and sustainability. During the last years, research has focused on dynamic chemistry, in order to introduce reversible bonds along the polymer chain and synthesize reprocessable and/or recyclable thermosets. In this context, the Diels-Alder reaction is of special interest, as it can give thermoreversible reactions with a relatively low coupling and high decoupling temperature. Within this work, a trifunctional polyol containing the furan-maleimide Diels-Alder adduct has been developed to facilitate the recycling of cross-linked polyurethanes. The maleimide-furan adduct forms covalent bonds at low temperatures, but when heated these bonds break down, splitting the polymer chain into smaller chains and softening the polymer, allowing it to be reprocessed. Then, when the temperature drops, the bonds between the maleimide and the furan are reformed and the polymer regains its mechanical properties. Thereby, a thermoset polyurethane was synthesized reacting the triol containing Diels-Alder adduct with a polymeric isocyanate. The reprocessability and/or recyclability of the synthesized polyurethane was then evaluated by breaking it into small pieces and reprocessing them by pressing at high temperature, in order to obtain new sheets and evaluate their mechanical properties, being similar to the original ones.

  Abstract
  Thermosets comprise a family of chemically cross-linked networks formed by irreversible chemical reactions, resulting in polymers with outstanding properties such as superior [...]

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• Impact behavior of thermoplastic matrix composites reinforced with basalt fibers and manufactured by RTM

  M. Baskaran, R. Hoto, J. García-Manrique, J. Aurrekoetxea

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 4 - Sostenibilidad y Reciclaje), 16

  
  

  Abstract

  Reducing the environmental impact of composite materials by using new matrices and fibres, as well as a manufacturing process that allows obtaining high-quality standards, is on the strategic agenda of academia and industry. Replacing thermosetting matrices with thermoplastics is a challenging vector for improvement, facilitating recycling. Regarding the fibres, natural fibres of mineral origin, such as basalt, reduce the ecological footprint in the raw material extraction phase. Characterising the impact behaviour of these new composites is necessary to identify potential applications. Otherwise, direct comparison with reference materials is essential since differences in the manufacturing process, fibre content, or test conditions make it impossible to put the new material in context. In this paper, we compared the impact properties of two thermoplastic-matrix (pCBT) composites manufactured using resin transfer moulding (RTM). On the one hand, as a reference material, the pCBT is reinforced with carbon fibres, and on the other hand, with basalt fibres. The results are better for the composite reinforced with basalt fibres, regardless of whether the properties are compared in absolute terms (×2.2), in weight reduction (×1.8) or in reduction of energy consumed during the primary production of the fibres (×4.4). 

  Abstract
  Reducing the environmental impact of composite materials by using new matrices and fibres, as well as a manufacturing process that allows obtaining high-quality standards, [...]

  • 24
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• Elastomeric composite materials reinforced with natural fibers and with self-healing capacity

  S. Utrera-Barrios, O. Lopes, M. Hernandez Santana

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 4 - Sostenibilidad y Reciclaje), 17

  
  

  Abstract

  Elastomeric composite materials are widely used in multiple applications, especially in the automotive industry; however, they have the drawback of being difficult to recycle, generating a significant environmental impact. For this reason, in recent years there has been an increase in research for the development of self-healing and biodegradable materials that minimize this impact by extending their lifetime. In this context, the aim of this work is to design a new generation of self-healing elastomeric composite materials using additives of natural origin. For this, epoxidized natural rubber (ENR) and cellulose propionate (CP) were used as matrix, reinforced with cellulose fibers. Self-healing was achieved by combining the flow of the thermoplastic (CP) phase (extrinsic mechanism) and the formation of hydrogen bonds between the ENR and the CP (intrinsic mechanism). A promising repair efficiency of 95% was obtained, as well as an increase in tensile strength in the presence of cellulose fibers, without affecting the healing capacity of the material. Therefore, this work overcomes the well-known dichotomy between mechanical performance and self-healing and constitutes a new contribution in the field of self-healing elastomeric composites using bio-based additives.

  Abstract
  Elastomeric composite materials are widely used in multiple applications, especially in the automotive industry; however, they have the drawback of being difficult to recycle, [...]

  • 61
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• New life for aeronautical dry carbon fiber

  A. Calero, T. Blanco Varela, J. Sistach

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 4 - Sostenibilidad y Reciclaje), 18

  
  

  Abstract

  Our latest generation aircraft are more efficient by design, lighter and emit on average 25% less CO2 than previous generation aircrafts. Lightweight materials like composites have contributed significantly to reach the current emissions levels, like the A350 with more than 50% of structural weight made of composites. However, composites drive also the environmental footprint of the aircraft life-cycle without considering the operational phase, involving currently important drawbacks in terms of energy consumption and waste recycling. The transition towards a composite circular economy needs to be anticipated due to the aviation sector de-carbonization challenge as well as the regulation evolution. This transition will be leveraged by several elements, being the composite recycling one of the most important, due to the need to transform the composite waste from production and end of life into new added value materials. For this, the development of efficient composite recycling technologies to not only recover energy during incineration but also high value recycled carbon fibers and semi-products are needed. This project was focused on the recycling of dry carbon fiber scrap, which can proceed from part production by infusion technologies (e.g. RTM) or from pyrolysis of end of life composite part. The approach was to obtain a non-woven mat from the dry fiber scrap, following a mechanical process, which was, then, fully characterized to identify potential applications in aeronautical field. Different approaches of hybridization of the recycled non-woven fabric with virgin fabric were also evaluated.

  Abstract
  Our latest generation aircraft are more efficient by design, lighter and emit on average 25% less CO2 than previous generation aircrafts. Lightweight materials like composites [...]

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• Thermochemical recycling of epoxy matrix composite materials with Diels-Alder bonds

  I. Lorero, C. Bravo, M. Campo, A. Jiménez, S. Prolongo, I. Lorero

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 4 - Sostenibilidad y Reciclaje), 19

  
  

  Abstract

  The high cross-linking degree of thermosetting resins, which gives them remarkable mechanical properties, also implies an irreversible structure that impedes proper recycling at the end of life. This problem influences both thermosetting matrices and composite materials, since the crosslink irreversibility of the matrix hinders the recovery of the fibers. One way to solve this problem is the development of new thermosetting resins that incorporate Diels-Alder thermo-reversible bonds. The introduction of Diels-Alder bonds allows thermosets to have a polymeric network capable of disengaging at temperatures above 90 °C, acquiring certain fluidity and recyclability. However, its composition and curing cycle must be carefully adjusted to avoid undesired chemical reactions and to maintain certain mechanical properties, since the addition of Diels-Alder bonds in high contents usually results in a notable embrittlement of resin. In the present work, the manufacture of an epoxy matrix composite material with 60% Diels-Alder bonds reinforced with carbon fiber is developed, which shows mechanical properties similar to those of a conventional epoxy resin laminate. After that, the recovery of the fiber is addressed thermochemically by dissolving the matrix in dimethyl sulfoxide at 150 °C, achieving the reuse of the fiber to manufacture new composite materials with mechanical properties comparable to the original.

  Abstract
  The high cross-linking degree of thermosetting resins, which gives them remarkable mechanical properties, also implies an irreversible structure that impedes proper recycling [...]

  • 9
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• Solvolysis of carbon fibre reinforced composites under mild conditions

  L. Fulgencio, A. Asueta, S. Arnaiz, J. Leivar, I. Amundarain, R. Miguel, A. Iruskieta, L. Fulgencio

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 4 - Sostenibilidad y Reciclaje), 20

  
  

  Abstract

  Carbon fibre reinforced composites (CFRP) are key in different industrial sectors as they combine lightness and robustness. This circumstance and the growing need to take advantage of the resources of any product, has triggered a strong demand to establish sustainable technological solutions that allow the effective use of composite materials: resins (matrix) and fibres (reinforcement). Limited to mechanical recycling, recycling alternatives for CFRP with thermosetting resins have focused on thermochemical treatments, usually pyrolysis to recover the fibres, degrading the matrix. In addition to thermal routes, solvent treatments under supercritical conditions have also been studied. However, these processes exclude resin recovery and involve a partial loss of mechanical properties of the fibres due to the heat treatment (450-550 °C). As an alternative, a solvolysis using mild conditions is proposed to treat CFRPs with amine-hardened epoxy resins, so that the fibres are recovered with all their properties and the organic matrix is materially valorised. This process is applied to reference materials of known composition and validated with real residues with good results in terms of degree of resin decomposition. The recovered fibres show almost resin-free surface and seem to have mechanical properties comparable to those of virgin fibres.

  Abstract
  Carbon fibre reinforced composites (CFRP) are key in different industrial sectors as they combine lightness and robustness. This circumstance and the growing need to take [...]

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• Thermoset polyurethanes based on recycled and biobased constituents

  E. Mendiburu-Valor, I. Larraza, O. Echeverria Altuna, I. Harismendy, A. Eceiza

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 4 - Sostenibilidad y Reciclaje), 21

  
  

  Abstract

  Poly(ethylene terephthalate) (PET) is one of the most consumed plastics in the world, so it is very common to find it in the sea or ocean. Thermomechanical recycling is normally used for urban and industrial PET waste, but it is not suitable for highly degraded marine litter. Chemical recycling of marine PET litter is presented as an alternative for the valorization of this highly degraded waste. The bis(2-hydroxyethyl) terephthalate (BHET) monomer obtained can be used in the synthesis of new polymers. This study explores the potential of using BHET for the synthesis of high modulus and high strength thermoset polyurethanes. In addition, a renewable reagent, such as a polyol derived from castor oil, has been used to synthesize a recycled and biobased polyurethane thermoset (BHET-BioPU). The resulting BHET-BioPU has been thermally, thermo-mechanically and mechanically characterized to evaluate its potential applications. In addition, the recyclability by glycolysis of the BHET-BioPU has been demonstrated, thus advancing towards a circular economy. The results of this study provide fundamental knowledge for the development of sustainable, environmentally friendly and high performance materials and recyclable as well, materials, and represent an important achievement in the global effort to reduce dependence of fossil resources and plastic pollution.

  Abstract
  Poly(ethylene terephthalate) (PET) is one of the most consumed plastics in the world, so it is very common to find it in the sea or ocean. Thermomechanical recycling is normally [...]

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• Validation of a laboratory-scale technology for complete recycling of wind turbine blades

  A. Lopez-Urionabarrenechea, A. Serras-Malillos, E. Perez-Perez, B. Perez-Martinez, E. Acha, B. Caballero, A. Lopez-Urionabarrenechea

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 4 - Sostenibilidad y Reciclaje), 22

  
  

  Abstract

  This paper presents the experimental validation of a thermal treatment technology to recover added-value substances from the plastic matrix of end-of-life wind turbine blades, when these are subjected to a pyrolysis process to recover the glass fibres. The experiments have been carried out in a laboratory installation consisting of two reactors in series, in which pyrolysis and thermal treatment of pyrolysis gases and vapours take place, respectively. The application of this treatment enables a 25 wt.% reduction in the production of pyrolysis liquids, increasing the production of gases in an equivalent way and without compromising the pyrolysis conditions to be used to recover the glass fibres. The two-phase liquids are converted into single-phase aqueous ones, while the hydrogen concentration in the gases increases from 4 % to almost 50 % in volume. This high concentration of hydrogen in the gases allows them to be used as a source of hydrogen for various applications. Consequently, the technology demonstrates that the plastic matrix of wind turbine blades can be valorised in a pyrolysis based recycling process.

  Abstract
  This paper presents the experimental validation of a thermal treatment technology to recover added-value substances from the plastic matrix of end-of-life wind turbine blades, [...]

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• New functionalities and recycling opportunities for dynamic epoxy-based composites

  A. Rekondo*, I. Azcune, A. Huegun

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 4 - Sostenibilidad y Reciclaje), 23

  
  

  Abstract

  Reprocessable, repairable, and recyclable thermoset composites have the potential to improve the circularity of composites and ensure their sustainability. Disulfide-based epoxy matrices are under development to meet the specifications of key sectors (transport, wind energy, etc.). The manufacturing of reinforced composites by different techniques (infusion, prepregs, etc.) has been validated (TRL 4-5). The incorporation of new functionalities, such as fire resistance, and the validation of recycling are now on the table. Conventional chemical recycling separates the reinforcement from the composite for reuse, leaving aside the polymer matrix. The new functionalities incorporated require recovery and validation of the matrix. Dynamic resins allow milder conditions to be applied during recycling, and the challenge remains to find new applications that reuse these recycled products. On the other hand, the rational use of resources demands for new recycling routes that do not require separation of the components, apply few steps, be economically viable, and maintain the value of the reinforcement and the matrix. Vitrimers allow the thermoforming of composite parts through the application of heat and pressure. This process opens the way from reusing final parts with new shapes to generating short new fibre composites from mechanical pre-crushing. This communication will present the latest developments and objectives of several European projects funded under the HE framework (SURPASS, GA no. 101057901; MC4, GA no. 101057394) in which work on the maturity of the technologies is in progress.

  Abstract
  Reprocessable, repairable, and recyclable thermoset composites have the potential to improve the circularity of composites and ensure their sustainability. Disulfide-based [...]

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Núm. 5 - Materiales y Estructuras

• Flame retardancy of thermoplastic and thermoset prepregs incorporating superficial flame-retarded layers

  A. Allue, J. Gómez, S. Neira, J. Ballestero, P. Elejoste, K. Gondra

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 5 - Materiales y Estructuras), 24

  
  

  Abstract

  The concept of lightening has been essential for the use of composites in different industrial sectors, especially in transport applications. Composites are strategic for the objectives of sustainable mobility, being the behaviour against fire, one of the aspects to improve in these materials. For this reason, the flame retardancy of thermoplastic prepregs and thermosetting prepregs, applicable to the transport sector, has been studied by incorporating superficial flame-retardant layers based on expandable graphite. In the case of thermoplastic composites, work has been done with polypropylene laminates reinforced with fiberglass fabrics, addressing flame retardancy by incorporating a functional layer of expandable graphite. In the case of thermosetting composites, furanic basalt fibre and recycled carbon fibre prepregs have been studied. The flame retardancy of basalt prepregs has been addressed incorporating halogen-free flame retardants in thermosetting matrix, and the flame retardancy of recycled carbon fibre prepregs has been addressed by a combined strategy incorporating halogen-free flame retardants in thermosetting matrix and superficial fire-retardant layers on the composite, based on expandable graphite.

  Abstract
  The concept of lightening has been essential for the use of composites in different industrial sectors, especially in transport applications. Composites are strategic for [...]

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• Advanced lightweight materials for Energy-efficient Structures

  B. Galindo, R. Ruiz, F. Ramos, . A.Crespo, F. Ramos Saz

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 5 - Materiales y Estructuras), 25

  
  

  Abstract

  In the present study will show the concept of FOREST project which will contribute to the decarbonisation of the transport sector by developing and implementing innovative bio-based polymers & additives and recycled carbon fibres. FOREST will develop novel lightweight multifunctional biocomposites as a competitive alternative to conventional composites. New chemistries will be developed based on bio-based materials (reactive and nonreactive polymeric systems and fire-retardant additives) in combination with fully recycled carbon fibre and EMI particles. These biocomposite candidates will be obtained using one-shot manufacturing techniques, involving out-of-autoclave (OOA) processes to build and test prototypes (TRL5) with improved multifunctional properties (mechanical resistance, fire-retardant, EMI-shielding) for transport applications.

  Abstract
  In the present study will show the concept of FOREST project which will contribute to the decarbonisation of the transport sector by developing and implementing innovative [...]

  • 36
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• ENDURING PREPREGS THANKS TO THE USE OF DYNAMIC EPOXY RESINS

  A. Genua, I. Aranberri, A. Salaberria

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 5 - Materiales y Estructuras), 26

  
  

  Abstract

  The use of CIDETEC's patented 3R technology allows the development of thermoset composites that are intrinsically Reprocessable, Recyclable and Repairable (3R). These materials are very interesting for sectors as diverse as energy, transport, and construction, as they maintain the high performance of conventional thermoset composites and can be processed using common manufacturing technologies. The use of prepregs is one of the methods used to manufacture thermoset composites, but it is a labour-intensive and cost-intensive process. In addition, the epoxy matrix of prepregs, which is partially cured (called B-phase) and sticky, requires them to be stored cold (refrigerated or frozen) and, once the due date has passed, they cannot be used to form a consolidated laminate because of their lack of adhesion. The dynamic character of the 3R epoxy resin described here makes it possible to manufacture what we have called "enduring prepregs", which are (semi-)cured, non-perishable prepregs, with the advantage that they can be stored at room temperature without losing their adhesion capacity. Moreover, it is possible to process them using techniques as diverse as AFP (automated fibre placing) or thermoforming to manufacture multilayer composite parts. This communication will present the latest advances and the objectives of several European projects funded under the H2020 (CARBO4POWER - GA.953192) and Horizon Europe (BIO-UPTAKE -GA. 101057049 and GENEX -GA. 101056822) frameworks, which are working on the development and optimisation of these "enduring prepregs" for different sectors.

  Abstract
  The use of CIDETEC's patented 3R technology allows the development of thermoset composites that are intrinsically Reprocessable, Recyclable and Repairable (3R). These [...]

  • 8
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• Morphological study of refractory composite materials based on magnesia (MgO) with additions of hercinite (Fe2Al2O4)

  C. Gomez Rodriguez, B. Escobedo-Trujillo, L. Verdeja, D. Fernández-González, A. Fernández, L. García-Quiñónez, G. Rodríguez

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 5 - Materiales y Estructuras), 27

  
  

  Abstract

  Since the refractory materials are immersed in aggressive environments, the deterioration is evident because they are affected by slags, gases or liquids that corrode the material. Materials used in the refractory lining of the rotary furnace of cement are densified materials with high resistance, particularly magnesia bricks (MgO) with second phases to improve their characteristics. Within this investigation, formulations with refractory powders were developed, which were uniaxially pressed at 100 MPa and sintered at 1650 °C for four hours. Up to a maximum of 20 wt.% of hercynite (Fe2Al2O4,) was added as second phase to the refractory matrix of magnesia (MgO). The morphological characteristics as well as the mechanical properties of the sintered samples, in a conventional electric furnace, were studied by scanning electron microscopy (SEM) with Energy-dispersive X-ray spectroscopy (EDX). As a result, it was checked that, the temperature used in the experiments was not sufficient to obtain sintered specimens of the MgO powders (100 wt. %). The additions of Fe2Al2O4 helped to obtain morphologically densified specimens. A 10 and 20 wt. % of Fe2Al2O4 promoted the grain growth during the sintering process.

  Abstract
  Since the refractory materials are immersed in aggressive environments, the deterioration is evident because they are affected by slags, gases or liquids that corrode the [...]

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• Buckling of composite material panels with holes

  M. Huertas, J. Esteban

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 5 - Materiales y Estructuras), 28

  
  

  Abstract

  The stability of composite material plates is being developed following basically two procedures: finite element analysis (FEA) and mathematical approaches using the energy method. The advantage of the finite element models is that they can be used with any geometry, configuration and load combination. However, it requires a significant pre-processing, computation and post-processing time of the results. On the other hand, analytical methods require much less time to obtain the results compared to them, but are limited to just basic geometries, such as rectangular panels without lightening holes. In this work, an analytical approach based on the energy method for buckling analysis of composite panels with holes has been developed. The innovation of this method is the inclusion of holes with different shapes in any position of a trapezoidal panel submitted to any in-plane loads combination. An exhaustive validation has been performed using FEA models and test results.

  Abstract
  The stability of composite material plates is being developed following basically two procedures: finite element analysis (FEA) and mathematical approaches using the energy [...]

  • 5
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• Silicon nitride-reinforced silicon oxycarbide nanocomposites with high thermal and mechanical performance

  M. Mazo

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 5 - Materiales y Estructuras), 29

  
  

  Abstract

  Si3N4 has high thermal and mechanical resistance, as well as high resistance to thermal shock and high thermal conductivity (320 Wm-1K-1). On the other hand, silicon oxycarbide glasses (SiOC) have a SiO2 matrix where part of the oxygen has been replaced by carbon and also contain a carbon phase homogeneously embedded within the mixed Si-O-C matrix. The properties of these materials can be designed depending on the precursors, synthesis-processing conditions, pyrolysis temperature and, above all, the addition of reinforcement materials, being able to obtain materials with certain characteristics depending on the application. In this work, dense SiOC/Si3N4 composite materials have been developed using the non-conventional sintering technique spark plasma sintering (SPS), which reduces the temperature and sintering times since it simultaneously uses a uniaxial pressing and an electric current to produce sintering by means of the Joule effect. Sintering improves as the temperature increases from 1500 to 1700 ºC. A large increase in thermal conductivity from 1.4 to 1.7 wm-1K-1 is observed in the composite materials obtained. These materials show good mechanical strength with microhardness and elastic modulus values of 10.2 GPa and 82.1 GPa, respectively, and an extraordinary resistance to oxidation. All these results indicate that these materials are excellent candidates for high temperature structural and functional applications such as solar receiver collectors and propulsion systems.

  Abstract
  Si3N4 has high thermal and mechanical resistance, as well as high resistance to thermal shock and high thermal conductivity (320 Wm-1K-1). On the other hand, silicon oxycarbide [...]

  • 28
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• Tecnologías de fabricación avanzadas en material compuesto termoplástico dirigidas al sector aeronáutico

  M. Mendizabal, S. García-Arrieta, E. Bellvert, X. Irastorza

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 5 - Materiales y Estructuras), 30

  
  

  Abstract

  La fabricación avanzada en materiales compuestos termoplásticos es clave para satisfacer los requerimientos del sector aeronáutico. Las ventajas diferenciadoras de los polímeros termoplásticos de alto rendimiento frente a las resinas termoestables, hace que estos materiales sean cada vez más demandados en el sector. Es clave su capacidad de reprocesado que permite 1) la automatización de los procesos, 2) la utilización de la tecnología de unión por soldadura entre sus componentes y 3) aplicar criterios de reciclabilidad y reutilización, imposibles para los materiales termoestables. Su mayor tenacidad y su cumplimiento de los estándares más estrictos de llama, humo y toxicidad aportan un plus importante a sus prestaciones. Polieterimida (PEI), Sulfuro de Polifenileno (PPS), Polieteretercetona (PEEK), Polietercetonacetona (PEKK) y el novedoso poliariletercetona (PAEK) son las matrices empleadas en esta tecnología de materiales compuestos termoplásticos de altas prestaciones. En función de la tipología del componente final, se selecciona la tecnología de procesado más adecuada, dependiendo de aspectos como geometría de pieza, tamaño y número de piezas a fabricar. El objetivo del presente trabajo fue la exploración de tecnologías de procesado de composites termoplásticos, tales como: Termoconformado de láminas compuestas (organosheet), obtención de laminados customizados (tailored sheet consolidation) y moldeo de escamas y/o pellets reforzados mediante compresión (T-BMC, Thermoplastic Bulk Moulding Compound) a través del desarrollo y puesta a punto de la fabricación de prototipos. Los resultados demostraron que estas tecnologías cumplen los requerimientos exigidos por el sector aeronáutico tanto en procesabilidad como en propiedades.

  Abstract
  La fabricación avanzada en materiales compuestos termoplásticos es clave para satisfacer los requerimientos del sector aeronáutico. Las ventajas [...]

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• Admissible values for the interaction term of the Tsai-Wu failure theory under plane stress and fitting of the failure envelope to test data

  O. Pellejer, A. Fernández, L. Cui

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 5 - Materiales y Estructuras), 31

  
  

  Abstract

  The Tsai-Wu failure criterion is widely used for orthotropic composite materials under plane stress due to its simplicity and low number of material constants. However, there is no consensus on how to find the interaction term. Based on general failure mode interaction assumptions, this paper provides closed form expressions to find the interaction term. In addition, the suitability of the Tsai-Wu’s failure criterion is narrowed to materials whose properties meet specific relationships. Last, it is shown how the Tsai-Wu failure envelope can be defined to pass through four biaxial stress states that best represent the actual testing conditions. All these findings conform an easy-to-apply methodology to define the Tsai-Wu failure envelope that best fits specific assumptions and test data.

  Abstract
  The Tsai-Wu failure criterion is widely used for orthotropic composite materials under plane stress due to its simplicity and low number of material constants. However, there [...]

  • 10
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• Performance of eco-composite sandwich panels manufactured by vacuum bagging infusion

  M. Teixeira, L. Amorim, A. Araújo, R. Santos, S. Sousa

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 5 - Materiales y Estructuras), 32

  
  

  Abstract

  The construction industry uses a complex combination of materials associated with a high carbon dioxide footprint. Therefore, several new building systems and solutions have emerged with higher sustainability and improved energy efficiency over their service lives, with the development of customizable lightweight sandwich structures, being one of the most promising strategies. The common processes for manufacturing fibre-reinforced polymer (FRP) composites, with large dimensions, are both hand layup-assisted vacuum bagging and vacuum bagging infusion. Besides, composite sandwich panels are traditionally composed by glass fibres and thermoset resins. However, basalt fibres can be an interesting substitute, since they are more sustainable, and have a higher performance. Despite the large amount of research work carried out on advanced composite sandwich panels, only a few studies were focused on the manufacturing of these structures based on basalt fibres assisted by vacuum infusion. Therefore, this work aims to design, manufacture and compare the mechanical, physical, thermal and environmental performance of these composite sandwich panels, comprising either glass or basalt fibres, which will be further applied in modular construction. The results revealed that it is feasible to produce composite sandwich panels through this method, and the most promising solution attained through this study is based on basalt fibres.

  Abstract
  The construction industry uses a complex combination of materials associated with a high carbon dioxide footprint. Therefore, several new building systems and solutions have [...]

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• Analysis of fiber-reinforced thermoplastic composite/metal sheets for the automotive sector

  D. Grau, A. Marques, O. Gonzalez, B. Neto, A. Marques

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 5 - Materiales y Estructuras), 33

  
  

  Abstract

  The recent trend to replace Body-in-White components with carbon fibre laminates, known as “Body in Black”, has been taking hold in new vehicle designs. This is how various hybrids with a thermoplastic matrix are born, such as CAPET, which has titanium with carbon fibres in PEEK, CAPAAL, which has aluminium with carbon fibres and glass in PA 6, CATPUAL based on CAPAAL, with thermoplastic polyurethane matrix and aluminium sheets. This project includes the study and design of hybrid laminates that can replace a monolithic steel sheet. Analytical models based on the classical laminate theory and models based on the rule of mixtures were used to predict the mechanical behaviour of the material. The structural behaviour of a semi-product was analysed using finite element simulations. The results show that it is possible to obtain a weight reduction between 13% and 22% when using a hybrid laminate, but it is required to increase the thickness of the lamina up to 3 times compared to the metal. Subsequently, studies were carried out to measure the wetness of the surface and the adhesion resistance of a carbon fibre prepreg with PA6 matrix on aluminium. A life cycle analysis (LCA) of hybrid laminates designed to observe the environmental impact on energy consumption and carbon footprint was carried out. 

  Abstract
  The recent trend to replace Body-in-White components with carbon fibre laminates, known as “Body in Black”, has been taking hold in new vehicle designs. This is [...]

  • 10
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• Improvement of electrical resistivity of cement mortar through nanotechnology

  A. Yedra, C. Manteca, B. Santos, L. Pérez-Gandarillas

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 5 - Materiales y Estructuras), 34

  
  

  Abstract

  The diffusion or permeability of ions or gases through the cement matrix is key in the degradation of reinforced concrete for marine applications. The delay in ion diffusion has been an important approach to extend the life of this type of materials. In this work it is detailed how reduce degradation of cement mortar using nanotechnology. The addition of nanoparticles to the cement paste has important implications for the hydration and microstructure, reducing porosity and improving mechanical properties. In this study, different nanoparticles have been used to reduce the porosity of mortars evaluating this improvement by means of electrical resistivity measurements. It is perfectly established the porosity reduction with the increasing of electrical resistivity. Reduction of porosity minimises the intake of aggressive agents into the mortar in a meaningful way, retarding the corrosion of metal reinforcement. Nanoparticles addition (<10%) within cement mortar have allowed to increase the electrical resistivity in up to 112% regarding to control sample, without modifying of mechanical properties.       

  Abstract
  The diffusion or permeability of ions or gases through the cement matrix is key in the degradation of reinforced concrete for marine applications. The delay in ion diffusion [...]

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• Vol4 num2-4 Development of multi-material components for the automotive sector

  L. Mera, R. Mano, L. Blanco

  Materiales Compuestos (2022). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 5 - Materiales y Estructuras), 94

  
  

  Abstract

  The present work addresses different aspects of the manufacturing process optimization of structural components for the automotive sector. More precisley the development of a novel bumper beam is being pursued by combining steel and composite to achieve, ultimatly, a weight reduction of the current component. For this it has been fundamental to consider not only the requirements of the part, specially from the safety prespective, but also manufacturing criteria. The study carried out has included everything from the design of the component up to the evaluation of a wide range of composite materials, both of thermostable and thermoplastic nature. Thus, different manufacturing technologies together with their process window and tooling desing has been accomplished in this work. In addition, several surface treatment technologies including cutting-edge ones such as laser texturing, have been combined with different strategies to ensure, in this way, the optimal performance of the solution. Finally, the development of ad-hoc demonstrators has allowed identifying the most suitable design and materials. Also, it has been possible to quantify the performance of the components, process times and final cost. Finally, a 25% weight reduction has been achieved, maintaining the mechanical properties and cycle times down to 5 minutes.

  Abstract
  The present work addresses different aspects of the manufacturing process optimization of structural components for the automotive sector. More precisley the development of [...]

  • 3
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Núm. 6 - Fabricación y Aplicaciones Industriales

• rCF LM PAEK PRESS-MOULDING PROCESS OPTIMIZATION THROUGH THE INTRODUCTION OF A WAAM MOULD CORE

  A. Marqués*, J. Dieste, I. Monzón, C. Javierre, D. Elduque

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 6 - Fabricación y Aplicaciones Industriales), 35

  
  

  Abstract

  Carbon fibre matrix composites are consolidated in high-demanding industries such as aeronautics and aerospace. Nowadays, thermoset composites are fully integrated on several new aircrafts in production. However, thermoplastic composites are progressively emerging as a better solution due to their end-of-life recyclability and optimized manufacturing process. One of the processes used to manufacture final parts from thermoplastic composite materials is press-moulding, in which a high-temperature heating system is combined with the application of pressure at high speeds. This article studies the optimization of press-moulding process in combination with an Additive Manufacturing (AM) produced metallic mould core. The aim of this study is the manufacturing of a thermoplastic aeronautical part, that would be submitted to real-world performance test. For the press-moulding process, a high-temperature infrared heating system was designed, supported by thermal oil mould heating, this heating system was combined with a mould-pressing process by integrating the system in a commercial injection machine. Regarding the AM tooling, produced by Wire Arc Additive Manufacturing (WAAM) process, was designed to reduce tooling weight, and optimise thermal cycle. Moreover, manufacturing data from WAAM tooling was recorded and compared with that obtained from a symmetrical conventional manufacturing made mould. The analysis shows savings in terms of material and energy consumption, as well as cycle times reduction. The final part metrology study shows indistinguishable results between the press-moulding process carried out using the WAAM tooling and that manufactured through conventional methods.

  Abstract
  Carbon fibre matrix composites are consolidated in high-demanding industries such as aeronautics and aerospace. Nowadays, thermoset composites are fully integrated on several [...]

  • 53
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• PANELES FABRICADOS MEDIANTE CURADO UV DE PREPREGS FUERA DE AUTOCLAVE REFORZADOS CON PERFILES DE PULTRUSION UV

  I. Eguino, G. Goenaga, A. Arruti, I. Saenz-Dominguez, I. Tena, . , J. Aurrekoetxea

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 6 - Fabricación y Aplicaciones Industriales), 36

  
  

  Abstract

  This paper has demonstrated the potential of UV curing technology when applied to glass fibre reinforced composites. Two manufacturing routes for making panels have been compared: manufacturing each element by its side and their subsequent bonding, and the direct integration of the profiles in the UV curing of the skins. The results of interlaminar tests show that the strength of the prepreg/profile bond is comparable to that of the prepreg/prepreg bond. Consequently, the prototypes obtained with both strategies show similar mechanical performance, both in stiffness and flexural strength. Finally, the low-temperature UV curing of the skin allows the use of water-soluble cores manufactured by 3D printing, which facilitates lamination and compaction operations.

  Abstract
  This paper has demonstrated the potential of UV curing technology when applied to glass fibre reinforced composites. Two manufacturing routes for making panels have been compared: [...]

  • 0
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• CUSTOMISED AND INTEGRATED SOLE FOR CYCLING MANUFACTURED BY 3D PRINTING OF CONTINUOUS CARBON FIBRE REINFORCED POLYAMIDE

  A. Esnaola, U. Morales, M. Iragi, L. Aretxabaleta, J. Aurrekoetxea

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 6 - Fabricación y Aplicaciones Industriales), 37

  
  

  Abstract

  Customised cycling soles are extremely complex to design and manufacture since the plantar pressure distribution and anatomical shape are specific for every foot. This paper explores the potential of topology optimisation and additive manufacturing of continuous fibre reinforced plastic. The highly abstract material distribution resulting from the topology optimization software was interpreted considering the additive manufacturing constraints for getting the detailed design. The selected printing strategy consisted of concentric fibre orientation to better fit load-paths, and the build-orientation aimed to maximise the fibre content, resulting in 30 hours for printing each sole. Regarding the specific stiffness at the hallux and the hell, the new soles are at least 60% higher. Therefore, it has been confirmed that the proposed approach is a powerful tool to design the cycling shoe adapted to the local stiffness of each foot.

  Abstract
  Customised cycling soles are extremely complex to design and manufacture since the plantar pressure distribution and anatomical shape are specific for every foot. This paper [...]

  • 17
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• Active and biodegradable food packaging based on PLA reinforced with inorganic particles encapsulating essential rosemary oil

  R. Cerdá, J. Gomez-Caturla, A. Agüero, M. Arrieta, . O.Fenollar

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 6 - Fabricación y Aplicaciones Industriales), 38

  
  

  Abstract

  Poly(lactic acid) (PLA) is the most widely used bio-based and biodegradable polymer in the food packaging sector, due to its market availability, competitive cost and ease of processing. However, PLA has some limitations in terms of its mechanical, thermal and barrier properties, which can be improved by adding inorganic particles to the polymer matrix to obtain hybrid organic-inorganic composites with improved properties. Among all the inorganic particles, Halloysite Nanotubes (HTH) and Diatomaceous Earth (DT) are of special interest because their hollow structure offers the possibility of incorporating active agents inside them to be released in a sustained way to the food, extending their shelf life. In the present work, rosemary (Rosmarinus Officinalis) essential oil was encapsulated in the cavities of NTH and TD, the active particles were incorporated into a PLA polymeric matrix and processed by extrusion followed by cast-film process to simulate industrial conditions. The presence of NTH and TD improved the Young's modulus of PLA, while rosemary oil acted plasticising the system increasing the elongation at break allowing flexible films to be obtained. The obtained materials showed antioxidant capacity, demonstrating the potential to produce biodegradable active materials of interest in the food packaging sector.  

  Abstract
  Poly(lactic acid) (PLA) is the most widely used bio-based and biodegradable polymer in the food packaging sector, due to its market availability, competitive cost and ease [...]

  • 12
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• Graphite-chromium carbide composites with application in heat dissipation

  D. Fernández-González, M. Suárez, J. Piñuela-Noval, C. Gomez Rodriguez, L. Díaz, A. Fernández

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 6 - Fabricación y Aplicaciones Industriales), 39

  
  

  Abstract

  Heat dissipation is an issue that is acquiring great importance to increase the efficiency in the utilization of the energy and extending the lifespan of the equipment. Traditionally, heat dissipation has been carried out using metals, but the increase in the requirements of equipment and devices, composites have gained importance. Graphite based composites have relevance in heat dissipation, particularly when the disperse material is a metal or metal carbide. The reason is the great value of thermal conductivity combined with good mechanical properties and lightness. Research has focused until nowadays on the composite graphite-MoC, although there are other composites with great potential, as that proposed in this manuscript: graphite- Cr3C2. The preparation of the composite graphite-Cr3C2 consisted in mechanical mixing of the staring powders, subsequent obtaining of the green compact of 40 mm in diameter and, finally, sintering at 2000 °C for 20 minutes under an applied pressure of 30 MPa in the Spark Plasma Sintering apparatus. The sintered material exhibited electrical and thermal conductivities in the in-plane direction of 1.08 MS/m and 215 W/m · °C, respectively, and a flexural strength of 113 MPa, which makes this material a suitable candidate for its application in heat dissipation.

  Abstract
  Heat dissipation is an issue that is acquiring great importance to increase the efficiency in the utilization of the energy and extending the lifespan of the equipment. Traditionally, [...]

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• LIGTHWEIGHT STRUCTURE OF HIGH SPEED TRAIN (TALGO) CARBODY. COMPOSITE IN RAILWAY ROLLING STOCK

  F. Garcia*, E. Guerra, M. Cerdeira, J. Fernández, . V.Meroño, . C.Eraso, . J.Arrabal, . X.Valor, . B.López, . M.Ordoñez, . M.Seco

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 6 - Fabricación y Aplicaciones Industriales), 40

  
  

  Abstract

  Currently, the railway sector demands novel lighter designs for the structural components of rolling stock that compensate for the increase in weight due both to the incorporation of new technologies for passenger comfort and experience, as well as to face new environmental challenges (reduction of emissions, consumption power, etc). With this objective in mind, Aernnova-Talgo-FIDAMC-Tecnalia have proceeded to develop a car body structure design for a high-speed passenger car that introduces up to 70% of high-performance composite material (CFRP). This makes it possible to achieve weight reductions of more than 20% when it is compared to the original 100% aluminum structure. The solution combines frame, sidewalls and roof in an integral solution in CFRP with the usual solution in welded aluminum for the closing endwalls. The use of composite material for these structures also implies the introduction of non-conventional manufacturing methods for the railway sector (Semipreg-Sandwich-Pultrusion) with curing outside of autoclave and compliance with the demanding fire and smoke requirements of the EN 45545. The final objective of the project is the bench validation of the prototype according to the usual standards of the railway sector, EN 12663.

  Abstract
  Currently, the railway sector demands novel lighter designs for the structural components of rolling stock that compensate for the increase in weight due both to the incorporation [...]

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• Application of machine learning for optimizing the heating process in in-situ consolidation of thermoplastic matrix composite materials

  A. Guillén, I. Martín, K. Fernández, L. Moreno, F. Domínguez

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 6 - Fabricación y Aplicaciones Industriales), 41

  
  

  Abstract

  This study explores the development and application of data-driven control techniques for managing the power of a laser system used in the in-situ consolidation process of thermoplastic materials (ISC). We discuss the correlation among the main variables - temperature, power, layer number, and lamination speed - and how these interactions inform the design of our control models. Two types of prediction models, multiple polynomial regression and support vector machines are compared. Though the software solution developed here is for testing purposes and not for production, we demonstrate the utility and flexibility of machine learning control approaches for this type of manufacturing process.

  Abstract
  This study explores the development and application of data-driven control techniques for managing the power of a laser system used in the in-situ consolidation process of [...]

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• UAV platform fabrication using 3D printing with embedded sensors and printed wires

  E. Soria, R. Herrero*, E. Tellechea, G. Argandoña, L. Jofré, M. Jofré

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 6 - Fabricación y Aplicaciones Industriales), 42

  
  

  Abstract

  By 2050, 68% of people will live in urban areas, which will create increasing pressure on the mobility infrastructure, increasing certain problematic aspects of cities. As cities get bigger, efficient, and sustainable urban mobility will become a major challenge. To address this problem, it is fundamental to be able to design cities taking into account the 3 possible dimensions, and to develop technologies that allow the air mobility of both goods and people. Drones are seen as a medium-term solution to these problems. A drone has been manufactured using a Composites 3D printer. The design of the unmanned aerial vehicle (UAV) has been carried out and the manufacture of the different elements using long and short carbon fiber, looking for the configuration that provides the best combination of mechanical properties with a lower weight of the drone. Extensiometric gauges are designed and printed on a flexible substrate using a combination of conductive and dielectric inks and the gauges are embedded in the composite during the manufacture of the pieces. These embedded gauges allow monitoring the flexion produced in flight of the drone frame, monitor bumps and defects during the useful life of the drone and increase the functionalities of the UAV without increasing the weight of the same and the number of elements. Likewise, the conventional wiring has been replaced by printed wiring making the connections between the motors and the speed controllers.

  Abstract
  By 2050, 68% of people will live in urban areas, which will create increasing pressure on the mobility infrastructure, increasing certain problematic aspects of cities. As [...]

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• Improvement of the impact behavior of forged composite plates reinforced with continuous fiber tapes

  U. Olaziregi, M. Baskaran, U. Morales, A. Esnaola, J. Aurrekoetxea

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 6 - Fabricación y Aplicaciones Industriales), 43

  
  

  Abstract

  The conception of structural components using thermoplastic composite materials faces a dilemma when selecting the material/manufacturing process pairing. Continuous fiber-reinforced composites offer the best properties, but their design freedom is limited to shell-type parts. On the other hand, manufacturing processes for discontinuous fiber, such as injection (LFT) and forging (GMT), allow the production of complex geometries, but their mechanical properties are substantially lower. In fact, LFT and GMT are important in the current automotive industry, but their applications are limited to semi-structural components or internally complex geometries whose functionality is more focused on function integration rather than supporting high mechanical loads. The hybridization of discontinuous fiber composites with continuous fiber materials presents itself as a promising approach to achieve a synergistic effect from both technologies. In this study, the impact behavior of glass fiber-reinforced polyamide forged plates (GMT) was characterized, along with their hybridization with unidirectional carbon reinforcements. In the first phase, the effect of the processing temperature was investigated, concluding that increasing the temperature promotes the compaction between the two materials, resulting in improved impact resistance. Specifically, a 14% increase was observed in both maximum force and dissipated energy. In the second phase, the effect of hybridization with unidirectional tapes as reinforcement was analyzed, showing the same positive effect. The hybridization led to a 20% improvement in maximum force and a 36% increase in dissipated energy.

  Abstract
  The conception of structural components using thermoplastic composite materials faces a dilemma when selecting the material/manufacturing process pairing. Continuous fiber-reinforced [...]

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• AUTOMATED FIBER PLACEMENT OF THERMOPLASTIC MATERIALS: TOWARD A NEW WAY OF CONTROLLING TEMPERATURE HOMOGENEITY

  S. Réquilé, D. CARTIE, Y. Blanchard, M. Fariñas

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 6 - Fabricación y Aplicaciones Industriales), 44

  
  

  Abstract

  Automated fiber placement (AFP) is a highly efficient process to produce thermoplastic matrix composite parts. This process involves heating, compaction and cooling steps that must be understood and controlled to achieve an optimal process for the manufacture of structural parts. Heating using a laser provides many advantages due to high energy density and efficient control that are beneficial for process control and productibility [1]. However, the temperature distribution during the layup can be altered by process parameters, i.e., laser power, layup speed and compaction force [2, 3]. The geometric configurations of the laser and the temperature measurement device (IR camera) also need to be considered to control the heat flux distribution at the tape/substrate interface (nip point region) and temperature homogeneity of the part. At the composite scale, the consolidation quality is determined by governing mechanisms such as intimate contact development between plies, void consolidation, and adhesion, which are a function of temperature, time and pressure distribution [4].

  Abstract
  Automated fiber placement (AFP) is a highly efficient process to produce thermoplastic matrix composite parts. This process involves heating, compaction and cooling steps [...]

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• Scale up and automatization of an anti-ice coating for aircraft structures

  M. Rodríguez, R. Maeso, J. Ávila, V. García, V. García

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 6 - Fabricación y Aplicaciones Industriales), 45

  
  

  Abstract

  The current work contemplates both the scaling in the production of an icephobic coating based on an aeronautical paint as well as the automatic application of the aforementioned coating. In the automation process, a complex geometry demonstrator representative of a composite leading edge was selected. The functionality of the coating, which is based on getting low ice adhesion values, is strongly influenced by the morphology of the last sol-gel layer applied over the paint. For this reason, during the automation process it has been necessary to readjust different parameters of the robotic arm to achieve an adequate size and distribution of sol-gel droplets.

  Abstract
  The current work contemplates both the scaling in the production of an icephobic coating based on an aeronautical paint as well as the automatic application of the aforementioned [...]

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• Wingbox Component Integration by Liquid resin Infusion

  L. Rubio1, R. Tejerina1, A. Ibañez1, M. Vaca1, J. Guerrero1, R. Buelga1, A. Jiménez1, R. Barroso1, F. Martín1, S. García1, I. Romero1, M. Iglesias1, B. Nicolás1, A. Hernández1, V. Sánchez1, S. Díaz2

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 6 - Fabricación y Aplicaciones Industriales), 46

  
  

  Abstract

  Composite epoxy resin based structures are widely and increasingly used at aerospace sector. Conventional composite processing requires the use of pre-impregnated raw material that requires refrigerated storage and autoclave use for the component consolidation. ADS jointly with Mtorres and with Hexcel support, have been intensely involved in the development of a Dry fibre automatic lamination, Liquid resin infusion and oven consolidation technology process (shortly referred as LRI) which permits the elimination of this energy consuming steps in order to improve the sustainability and reduce manufacturing costs so as allowing an increasing component integration reducing structural weight. A LRI integrated lower cover with spars and stiffening elements has been delivered by CBC for its integration into an Outer external wing box specimen for its test, scheduled as the latest Milestone of Clean Sky 2 AIRFRAME ITD project (supported also by IIAMS, MALTA, CERTERIN R&T projects). This specimen will be assembled through a jiggles process with the delivered thermoplastic Upper Cover. The full scale test will complete the testing pyramid after having completed the previous steps: coupon, detail, panel level. This partial Lower cover demo so as the Full Scale test, in which it will be integrated, will contribute to the TRL6 maturity status of the technology. 

  Abstract
  Composite epoxy resin based structures are widely and increasingly used at aerospace sector. Conventional composite processing requires the use of pre-impregnated raw material [...]

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• Impact properties of layer by layer in-situ UV cured composites

  I. Ruiz de Eguino, I. Saenz-Dominguez, I. Tena, M. Sarrionandia, J. Aurrekoetxea

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 6 - Fabricación y Aplicaciones Industriales), 47

  
  

  Abstract

  Fast and eco-friendly composite curing technologies are highly sought after, and ultraviolet (UV) curing offers both features. UV curing can be applied as a bulk curing technology as long as light arrives at all the points in the material with enough intensity. Additionally, the outer layer cures almost instantaneously, reducing the emission of volatile organic compounds. Despite its benefits, the implementation of UV curing technology in composites manufacturing is still in an early stage, and more basic knowledge about its principles needs to be generated. For instance, when curing considerably thick laminates, the light arriving at the points in the material further from the exposed surface is insufficient for a one shot consolidation, requiring a layer-by-layer curing strategy. In the present paper, we explore several approaches for the layer-by-layer curing of a glass fibre reinforced unsaturated polyester composite. We assessed the impact properties of the manufactured laminates through drop weight low velocity impact tests to quantitatively evaluate the different approaches. We found that the laminate cured in three steps, applying four plies by shot, had the best impact performance, followed by the composite cured in two steps. On the other hand, the laminate cured in one shot had the worst impact properties, dissipating 20% less energy than the best performing laminate. Therefore, we conclude that the bonding of the UV cured laminates is tough and that the residual stresses induced during manufacturing are lessened the thinner the layers cured in each step are.

  Abstract
  Fast and eco-friendly composite curing technologies are highly sought after, and ultraviolet (UV) curing offers both features. UV curing can be applied as a bulk curing technology [...]

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• Rediseño de pieza de automoción en SMC mediante optimización topológica

  K. Zulueta, I. Madina, P. Larreategi

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 6 - Fabricación y Aplicaciones Industriales), 48

  
  

  Abstract

  Lightening vehicles has been and continues to be one of the main objectives of the automotive industry. On one hand, to reduce fuel consumption in internal combustion vehicles, and, on the other hand, to try to maximize the autonomy of electric vehicles. In this aspect, composite polymeric materials, such as Sheet Molding Compound (SMC) materials, play a decisive role; however, their use in structural parts requires appropriate design and simulation techniques. In order to maximize design possibilities, in the conceptualization phases of the product development process, topology optimization tools open many possibilities. Nevertheless, the use of this technique in SMC materials generates certain uncertainties due to the nature of the material. In this context, in this work a metal part has been replaced by a version of it in SMC and topological optimization tools have been used in the conceptual design stage. The possible variants have been analyzed when entering the mechanical data of the material, due to its anisotropic nature, as well as the influence of temperature on them, due to the fact that in the working environment the piece is subjected to 130 ºC. To do this, samples of material have been molded and a mechanical characterization has been carried out to understand the behavior of the material with respect to fiber orientation and temperature. Then, using the PTC Creo design tool, a topological optimization and subsequent adaptation were carried out to improve the processability of the component. The most promising versions have been virtually validated using finite elements with Abaqus software. In conclusion, this work has demonstrated the viability of using topology optimization techniques in the conceptual design of components with SMC materials. Furthermore, in combination with simulation techniques using finite elements, they have proven to be tools that reduce and perfect product development in composite materials.

  Abstract
  Lightening vehicles has been and continues to be one of the main objectives of the automotive industry. On one hand, to reduce fuel consumption in internal combustion vehicles, [...]

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Núm. 7 - Caracterización - Sostenibilidad y Reciclaje

• Structural, optical and electrical properties of semiconductor films TiO2: Mn for solar cells

  B. Asenjo, J. Gandía

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 7 - Caracterización - Sostenibilidad y Reciclaje), 1

  
  

  Abstract

  TiO2 is a semiconductor oxide with many applications due to its properties. To increase the electron transport of the material, it is usually doped with transition metal ions so as not to alter its chemical and mechanical stability and thus be able to use this material for the manufacture of solar cells. In this work, the effect of the incorporation of the Mn dopant on the optical and electrical structures of the TiO2 fims grown by chemical methods under different conditions and deposited by the spin coating technique on glass substrates. Using optical spectroscopy, the influence of the starting precursor, thickness of the fims and the concentration of the dopant was mainly observed with respect to transmittance.

  Abstract
  TiO2 is a semiconductor oxide with many applications due to its properties. To increase the electron transport of the material, it is usually doped with transition metal ions [...]

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• Characterization of composite joints welded by electrical resistance. Effect of processing parameters.

  M. Herrera*, . J.Sogorb, . S.Gonzalez, . F.Lasagni, M. Herrera

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 7 - Caracterización - Sostenibilidad y Reciclaje), 2

  
  

  Abstract

  One of the main advantages of using reinforced thermoplastic materials is the possibility of joining different parts by welding. Welding process avoids the use of mechanical joints, which increase the weight of the component and the manufacturing time; as well as adhesive joints, where it is difficult to ensure their quality. Welded joints are of special interest when applied in assembly processes with a high production rate. However, welded joints on high-rate components require research into new materials, processes, and inspection techniques. In this line, the present work analyzes the results obtained from different welded joints through heating by electrical resistance without contact. This characterization study includes mechanical, microstructural and physical-chemical properties analysis, as well as its evaluation through non-destructive inspection techniques. As a result, a deeper knowledge of the materials and processes has been obtained, including the effect of the different welding processing parameters. Different opening mode mechanical tests are presented in this study, as well as thermal analysis by differential scanning calorimetry to evaluate the effect of temperature and time applied during the welding process on the final properties. The quality of the process in the different joining elements has been verified with inspection by means of infrared thermography, correlating indications in the level of IR radiation with localized variations microscopy features (i.e.: amount of resin). In addition, a microstructural study has been carried out to assess the fiber/resin content of the material in the joint areas, as well as a complementary analysis using computed tomography and ultrasound.

  Abstract
  One of the main advantages of using reinforced thermoplastic materials is the possibility of joining different parts by welding. Welding process avoids the use of mechanical [...]

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• Recommended methodology in Specification UNE 0074:2023 to determine shear properties by means of the biaxial tension-compression test with a cruciform specimen

  M. Serna Moreno, S. Horta Muñoz, J. lopez cela

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 7 - Caracterización - Sostenibilidad y Reciclaje), 3

  
  

  Abstract

  The biaxial tension-compression test with a cruciform specimen on symmetrical angle-ply ±45º laminates is proposed as an alternative that improves the results of existing methodologies to determine the pure shear properties in principal material directions. The method satisfies the main requirements for shear tests: i) it concentrates uniform stresses and strains in the biaxially loaded area, from which the shear response can be extracted; ii) it is possible to observe the linear and non-linear stress-strain evolution up to failure levels higher than those of traditional tests; iii) the failure is triggered in the biaxially loaded region, what allows calculating not only the shear stiffness during the linear stage, but also the shear strength. In addition, in carbon fibre reinforced polymeric matrix laminates, it is possible to increase up to 40% the level of shear strain at the moment of failure using a biaxial anti-buckling accessory that prevents the appearance of instabilities in the arms of the specimen. In this work, the test methodology recommended in Specification UNE 0074:2023, prepared by the Technical Committee CTN 53/GT 8, is shown. The specification is based on the previous research carried out in the COMMUL and BISHEAR projects developed within the framework of the national programs of R&D&I programme oriented towards the challenges facing society 2016 and the "Proof of Concept" projects 2021.

  Abstract
  The biaxial tension-compression test with a cruciform specimen on symmetrical angle-ply ±45º laminates is proposed as an alternative that improves the results [...]

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• CHARACTERISATION OF MODE II INTERLAMINAR FRACTURE UNDER FATIGUE

  . A.Arrese, F. Mujika, J. Renart

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 7 - Caracterización - Sostenibilidad y Reciclaje), 4

  
  

  Abstract

  It is essential to understand the behavior of composite laminates against fatigue crack initiation and growth in order to accurately predict component service life and to establish safe maintenance periods. In this work, an extrapolation procedure to characterize the mode II fatigue behavior based on the J0i-C0i and Δ0i-C0i master curves is presented and validated. The extrapolation procedure, based on the compliance variation, assumes that all effects associated with damage are included in the equivalent crack length. In this method, new factored expressions for flexibility (C0i), Integral-J (J0i) and crack tip displacement (Δ0i) are defined and according to their polynomial expressions with respect to the equivalent crack length, invariant relationships between J0i-C0i and Δ0i-C0i are obtained for a given material system and test configuration. Once the master curves have been calibrated, the extrapolation procedure allows characterizing the fatigue behavior of a material system by determining the Paris law during the fatigue test, monitoring only the test flexibility and the maximum load with respect to the number of cycles.

  Abstract
  It is essential to understand the behavior of composite laminates against fatigue crack initiation and growth in order to accurately predict component service life and to [...]

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• Characterization of composite material at cryogenic temperatures of 20K and the influence of hydrogen on its mechanical properties

  M. Frovel*, J. Martínez, M. González, F. Cabrerizo, P. Hormigo, D. Hormigo, G. Carrión

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 7 - Caracterización - Sostenibilidad y Reciclaje), 5

  
  

  Abstract

  The use of hydrogen as an energy source is a promising strategy to replace fossil fuels, in addition to batteries and biofuels. The European aerospace industry is already working on the development of propulsion technologies with low or zero emissions and heavily considers hydrogen technology. It is favoured in aeronautics to store H2 in liquid form, LH2, at temperatures of 20K to have the highest possible energy density of the fuel. This means that all materials in contact with LH2 need to be characterized at this temperature. INTA began to carry out cryogenic tests on composite materials 27 years ago. Initially in the field of characterization of composite materials for tanks for reusable launchers. Later, the structural monitoring of LH2 tanks, the detection of hydrogen leaks and fuel cells have also been investigated. Currently, INTA is involved in the characterization of composite materials in LH2 tank projects and the composite material structures that these tanks carry for sustainable aviation. The article gives an overview of the activities carried out in the field of cryogenic tests of composite materials and provides data obtained in these tests, comparing the behaviour of different materials and different types of tests. In addition, the new lines of research that are being carried out at INTA in the characterization of composite materials and their behaviour before and after being in contact with hydrogen will be explained.

  Abstract
  The use of hydrogen as an energy source is a promising strategy to replace fossil fuels, in addition to batteries and biofuels. The European aerospace industry is already [...]

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• Experimental study of the importance of fiber breakage in the resistance of thermoplastic matrix composite materials subjected to compression after impact

  J. Pernas, F. Naya, C. Fernández, P. Zumel, F. Naya Montáns

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 7 - Caracterización - Sostenibilidad y Reciclaje), 6

  
  

  Abstract

  The post-impact strength of composite materials is one of the main design parameters of aeronautical structures in terms of damage tolerance. During the low-velocity impact test, from a threshold energy, the laminate only partially returns the energy received during the impact to the indenter (elastic recovery). The remaining energy is absorbed by the laminate and dissipated in the form of damage (interlaminar and intralaminar), plastic deformation of the polymer matrix and breakage of the carbon fibers. To date, few authors have attempted to quantify the participation of each of the damage mechanisms in the overall energy absorption process of the laminate due to their experimental difficulty. In this work, a methodology has been developed capable of performing damage of similar extent and location to that produced in a low-velocity impact, but without damaging the fibers, through the application of local induction heating. For this purpose, the residual strength and stiffness of AS4/PEEK laminates, subjected to impacts over a wide range of energies (30-70J), have been compared with those obtained in laminates damaged by electromagnetic currents, for equivalent damage extensions. The results reveal that the breakage of carbon fibers has a great influence on the loss of stiffness of the laminate, but not on its strength, confirming the role of delamination as the main responsible for the loss of the strength capacity of the damaged material.

  Abstract
  The post-impact strength of composite materials is one of the main design parameters of aeronautical structures in terms of damage tolerance. During the low-velocity impact [...]

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• Synthesis of hybrid acrylic-polyurethane biobased systems for adhesive applications

  O. Echeverria Altuna, I. Calafel, R. Rodriguez, N. Fernandez

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 7 - Caracterización - Sostenibilidad y Reciclaje), 8

  
  

  Abstract

  Hybrid acrylic/water-based polyurethane systems have been synthesized by a polymerization process in which acrylic monomers have been used as solvents in polyurethane systems. The polymerization has been carried out in four main stages The first stage in which a prepolymer has been obtained, a second stage in which the chain extension has been carried out. In the third stage has obtained the phase inversion and finally in the last stage has been carried out the synthesis of acrylic monomers. Polymerization was monitored by ATR-FTIR and gravimetry. The effect of incorporating a bifunctional chain extender and replacing a conventional PPG polyol with two types of commercial biopolyols (Priplast 1900, 48% renewable and Priplast 3294, 100% renewable) was analyzed. It has been proven that the addition of a second bifunctional chain extender improves the adhesive properties of the hybrid system, an effect that is enhanced by the use of biopolyols. It has been proven that the use of bio-based polyols is possible since they do not significantly reduce thermal properties, making it feasible to obtain a material with 20% renewable content.

  Abstract
  Hybrid acrylic/water-based polyurethane systems have been synthesized by a polymerization process in which acrylic monomers have been used as solvents in polyurethane systems. [...]

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• Development of bio-based fire retardant additives and study of their incorporation into epoxy matrices for the mobility and construction sector

  J. Izquierdo, B. Galindo, A. Gonzalez-Jimenez

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 7 - Caracterización - Sostenibilidad y Reciclaje), 9

  
  

  Abstract

  This study aims to develop innovative flame-retardant additives from renewable resources, which will ensure high fire protection, low environmental impact, low toxicity and good processability in conventional polymer manufacturing processes in bio-epoxy matrices.

  Abstract
  This study aims to develop innovative flame-retardant additives from renewable resources, which will ensure high fire protection, low environmental impact, low toxicity and [...]

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• Nuevo concepto de eco-composite híbrido de fibra natural y láminas de madera (FWL). Fabricación, caracterización mecánica y envejecimiento en agua de mar. New concept of natural fibre-wood hybrid eco-composite (FWL). Manufacturing, mechanical characterization and seawater ageing.

  A. Lopez-Arraiza, F. Valencia, E. Urtaran, G. Castillo-López, J. Aurrekoetxea

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 7 - Caracterización - Sostenibilidad y Reciclaje), 10

  
  

  Abstract

  RESUMEN En el presente trabajo se estudia un nuevo eco-composite tipo FWL (“Fiber-Wood Laminate”) obtenido mediante la hibridación de fibras naturales y láminas de madera. Para ello, se han fabricado laminados por infusión de bioepoxi (SuperSap®) reforzada con tres capas de fibra de lino bidireccional y dos chapas de madera de pino, una en cada cara del eco-composite. Posteriormente, se realizaron ensayos de tracción, impacto de baja energía (E0=1J-25J) y se inspeccionó el daño mediante ultrasonidos. Igualmente, se repitió la caracterización para laminados sumergidos un periodo de bioactividad marina de 6 meses. Los resultados muestran que el FWL presenta un aumento del módulo elástico del 58% frente al biocomposite de lino (FFRB). Tras la inmersión en agua de mar, se observa que la absorción de humedad provoca una caída de la rigidez del 4,6% y del 6,9% en el FWL y FFRB, respectivamente. Por otro lado, los umbrales de penetración y perforación del FWL son un 29% y 32% inferiores a los correspondientes del FFRB. Después de la inmersión, dichos umbrales se desplazan a valores superiores en ambos eco-composites, más significativamente en el FFRB, debido al efecto plastificante de la absorción de humedad que se pone de manifiesto en los distintos patrones de daño observados por inspección mediante ultrasonidos. En conclusión, las láminas de madera del FWL aumentan la rigidez a tracción del nuevo eco-composite y ejercen un efecto barrera frente a la absorción de humedad debido a la inclusión de la bio-resina en la estructura celular de la madera.   ABSTRACT The present work explores a new concept of eco-composite named FWL (“Fiber-Wood Laminate”) obtained by combining natural fibres and wood sheets. The studied FWL configuration consisted of a single thin pinewood veneer at each of the outer layers of a bidirectional flax fibre-reinforced bio-epoxy (SuperSap®) manufactured by infusion. Tensile and low energy impact (E0=1J-25J) tests were performed and the damage was analysed by ultrasonic inspection. Furthermore, the last characterization was also conducted on laminates after being immersed during a marine bioactivity period of 6 months. The results showed an increase in the Modulus of Elasticity by 58% in the FWL compared to the flax-reinforced biocomposite (FFRB). After seawater immersion, the stiffness decreased by 4.6% and 6.9% in the FWL and FFRB, respectively. The penetration and perforation energy thresholds of the FWL obtained by falling weight impact tests were 29 and 32% lower than those of the FFRB, respectively. The effect of seawater immersing entailed a displacement to higher values of the energy thresholds, mainly in those of the FFRB. The plasticizing result of moisture absorption was evident in the different damage patterns observed by ultrasonic inspection. In conclusion, the thin pinewood veneers increased the tensile strength of the new eco-composite. The epoxy matrix filled the cellular structure of the wood, which acted as a barrier to reduce the water absorbed by the flax fibres.

  Abstract
  RESUMEN En el presente trabajo se estudia un nuevo eco-composite tipo FWL (“Fiber-Wood Laminate”) obtenido mediante la hibridación de fibras naturales [...]

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• Characterization and properties of bio-aerogels composed of gelatin.

  L. Cruz, T. Abt, N. Candau, N. León, M. Sanchez-Soto

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 7 - Caracterización - Sostenibilidad y Reciclaje), 11

  
  

  Abstract

  Aerogels are low density foam-like materials that are obtained from a sol-gel process in which the solvent used is replaced by air without collapsing the previously formed three-dimensional structure. In this work, we have studied the properties of aerogels composites that have been generated only from natural substances, using gelatin as matrix, clay and tannic acid as modifiers and water as unique solvent. The aerogels were obtained through lyophilization. While pure gelatin aerogel behaves like an elastic and low-stiffness foam, the addition of tannic acid and clay allow obtaining high resistant foams, reaching of up to a 9-fold increase in the elastic modulus, maintaining very low densities ( 0.14 g/cm3). These increases were obtained, on the one hand, due to a change in the aerogel micro-structure that evolved from a layered towards a honeycomb one. On the other hand, the alkaline conditions employed lead to the oxidation of tannic acid that was then able to establish covalent bonding with the amino groups of gelatin. The presence of well-dispersed clay in the matrix significantly reduced the rate of thermal degradation of the compounds due to its rearrangement into a stable protective layer on the surface of the material. Under conditions similar to those developed in a fire, the compound exhibited low flammability and high resistance to the spread of fire thanks to the synergistic action between clay and tannic acid. The achievement of multifunctional properties in these natural aerogels, allows broadening its applications, making that eventually, can replace traditional petroleum-derived foams, such as polyurethane, polystyrene or phenol-formaldehyde that have a notable environmental impact.

  Abstract
  Aerogels are low density foam-like materials that are obtained from a sol-gel process in which the solvent used is replaced by air without collapsing the previously formed [...]

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• New materials for additive manufacturing based on recycled composite

  A. Torre Poza, A. Pedreira, A. Rodríguez, C. Martín, R. Losada

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 7 - Caracterización - Sostenibilidad y Reciclaje), 12

  
  

  Abstract

  LMPAEK/CF laminates collected from scrap waste of Automated Fiber Placement (AFP) manufacturing were recycled obtaining different fiber sizes. The fraction with the smallest average particle size was mixed with different concentrations (5, 10, 20, 30% wt.) of PEKK (60:40). Blends processability was assessed by means of differential scanning calorimetry (DSC) and rotational rheology. Lastly, the mixture with 5%wt of carbon fiber content and PEKK was used for the filament manufacturing. This filament was printed in a robotized cell equipped with a 6-axis robotic arm using a printing head with a 0.8mm nozzle. The mechanical characterization of the printed samples revealed a significant improvement in the mechanical properties compared with neat PEKK or LM-PAEK.

  Abstract
  LMPAEK/CF laminates collected from scrap waste of Automated Fiber Placement (AFP) manufacturing were recycled obtaining different fiber sizes. The fraction with the smallest [...]

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• Development of manufacturing processes of hybrid structures made of recycled thermoplastic material with unidirectional inserts

  A. Calle, . O.Echeverria, . X.Irastorza, I. Harismendy

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 7 - Caracterización - Sostenibilidad y Reciclaje), 13

  
  

  Abstract

  One of the most important challenges in the automotive field is to deal with the new regulations regarding the material’s recycling, following the guidelines of the Circular Economy, without losing properties. The hybridization of parts of recycled material combined with continuous fiber inserts could be a solution to this problem. Within the framework of the ZeKonp project, a study and optimization of the manufacturing process variables of compression moulding of hybrid structures with unidirectional tape inserts. has been carried out The starting material has been a plate of a semi-finished hybrid of GMT material obtained by scraps of UD tape from production waste. The reinforcement has been placed with a Multilayer automatic taping equipment. In order to optimize the process, variables such as the arrangement of the material, temperature and compaction pressure, the strategy and speed of deposition of the strips and the welding process of the materials have been studied. In addition to the reuse of the materials, the process and life cycles of the final product has also been taken into account in order to reduce the environmental impact throughout its life cycle

  Abstract
  One of the most important challenges in the automotive field is to deal with the new regulations regarding the material’s recycling, following the guidelines of the [...]

  • 44
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• New technologies in chemical recycling of composites: catalysis and sizings

  A. Barranca, N. Lardiés-Miazza, A. Luengo-Baranguán, A. Luengo

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 7 - Caracterización - Sostenibilidad y Reciclaje), 14

  
  

  Abstract

  The recycling of composites by pyrolysis is a technology still under development, and although it is beginning to be implemented, it still poses different problems to be solved to ensure its viability and profitability. Thus, key aspects such as the high energy consumption of the process, the search for commercial outlets for secondary products, as well as maximising the value of the main products, understood as the reinforcement fibres of the composite itself, must be tackled. Regarding the reduction of energy consumption, AIMPLAS is working on the use of microwave radiation as a more efficient source of energy than convection heating, studying the possibility of reducing the temperature of the process, analysing the effect of this radiation on the quality of the fibres obtained and the final mass balance of the different fractions. Additionally, AIMPLAS has worked on the study of the application of sizings, mainly in carbon fibres. AIMPLAS is working on the development of new products and the optimisation of the application method to obtain short fibres coated with sizings, showing the improvement in the mechanical properties of the final composite due to a better interaction with the resin.

  Abstract
  The recycling of composites by pyrolysis is a technology still under development, and although it is beginning to be implemented, it still poses different problems to be solved [...]

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• NEW SUSTAINABLE BIO-PUR FORMULATIONS FOR OFFSHORE RENEWABLE ENERGY

  O. Echeverria Altuna, O. Ollo, I. Larraza, I. Harismendy, A. Eceiza

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 7 - Caracterización - Sostenibilidad y Reciclaje), 7

  
  

  Abstract

  The development of sustainable composites has become in a major strategy for different sectors, such as the offshore renewable energy industry. Thermoset polyurethanes (PUR) offer some advantages for their use in structural composite parts, like their good thermal properties, adhesion with different types of fibers, ultra-fast curing, low viscosity and corrosion resistance, highlighting their resistance to fatigue and consequent durability. However, PUR have some environmental drawbacks, such as their petrochemical origin and low recyclability. Consequently, biobased PUR (BIO-PUR) formulated based on polyols derived from vegetable oils have aroused keen interest. Moreover, it is possible to incorporate recycled monomers in their formulation, which are obtained from highly degraded plastics collected from the sea. In addition, it is necessary to consider the PUR end of life to improve the composite sustainability. An interesting solution is the incorporation of dynamic bonds into the PUR network, with reversible capacity such as Diels-Alder, to improve the polymer recyclability. Therefore, this work has focused on the development of a new formulation of BIO-PUR with the required mechanical properties for structural applications in the marine environment. In addition, the integration of recycled monomers and DA bonds have been explored to improve the circularity of the developed resin. To this end, aspects ranging from analysis and synthesis to the characterization of the resins have been covered.

  Abstract
  The development of sustainable composites has become in a major strategy for different sectors, such as the offshore renewable energy industry. Thermoset polyurethanes [...]

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• Eco-design of lightweight structural parts for electric vehicles – ALMA project

  R. *, V. Ventosinos, A. Tielas, R. Vázquez, D. García

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 7 - Caracterización - Sostenibilidad y Reciclaje), 15

  
  

  Abstract

  A great deal of work on lightweight cost-effective strategies has been underway in the last decades to improve the electric vehicle efficiency and driving range. At the time, and according to recent EU project results, up to 30-40% weight reduction was achieved so far in the vehicle structure at prototype level, but further efforts need to be invested to push the technology up to the market. Besides, the adoption of circular economy principles across the entire life-cycle is needed to enable, on one hand, the integration of environmental and cost considerations at the early design stages and, on the other hand, new options for the end-of-life recovery, repair, reuse and recycling.  ALMA project aims to apply eco-design principles to redefine the vehicle architecture and develop a new 26% lighter multi-material body structure using novel advanced high strength steel grades, high performance composites and advanced steel-hybrid laminates. Specifically, Designing for Assembly and Disassembly (DFA/DFD) and Design for Recycling (DFR) methodologies have been targeted to ensure cost-efficient separation, recycling and recovery at the end-of-life (EoL). The ALMA project has also considered aspects for the selection of the best material and production process for the right application at the design stage. The integration of regulatory considerations from early stages of design, especially forthcoming legislative requirements on emissions and the forthcoming ELV directive was also part of the design process. As a result, the ALMA project intends to foster the adoption of a circular approach in the automotive sector, reinforced by the use of eco-design methodologies from early stages of the car conception and supported by LCA methodologies, helping the automotive industry to harmonize with circular economy principles: design to reduce the production of waste and pollution and extend life cycle for materials and products.

  Abstract
  A great deal of work on lightweight cost-effective strategies has been underway in the last decades to improve the electric vehicle efficiency and driving range. At the time, [...]

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Núm. 8 - Fabricación y Aplicaciones Industriales - Materiales y Estructuras - Modelos Numéricos

• Ultrasound-assisted compounding extrusion to improve dispersion of nanoreinforcements

  G. Francucci, E. Sierra, M. Sierra

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 8 - Fabricación y Aplicaciones Industriales - Materiales y Estructuras - Modelos Numéricos), 16

  
  

  Abstract

  The addition of nanoparticles can significantly improve the properties of polymers. However, the industrialized production of nanocomposites presents the technological challenge of correctly dispersing the nanoparticles in the polymer matrix. EURECAT has developed a device that can be connected to standard twin-screw extruders and provide ultrasound vibration to the molten material, thus aiming to improve the degree of dispersion of nanoparticles. The present work presents the experimental validation of this technology, including the construction of processing windows and the comparison of nanocomposites obtained by traditional compounding and ultrasound-assisted extrusion. The produced nanocomposites consist of 94% polypropylene and 6% nanoclays (Cloisite 20A). The properties analyzed are: fluidity (MFI), mechanical properties (traction), O2 barrier properties and microstructure (TEM). The MFI results and the increase in material stiffness suggested an improvement in nanoparticle dispersion when using the ultrasonic device, especially when the intensity was set to 60%. These observations were verified with the results of the barrier tests (to O2), which demonstrated that the ultrasound treatment was effective in reducing the O2 permeability of the compounds.

  Abstract
  The addition of nanoparticles can significantly improve the properties of polymers. However, the industrialized production of nanocomposites presents the technological challenge [...]

  • 3
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• Manufacturing of Thermoplastic Composite Upper Wing Skin by In-situ consolidation (ISC)

  . E.Lorenzo-Villafranca, M. Ruiz, P. Tabarés, R. Iglesias, M. (2)

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 8 - Fabricación y Aplicaciones Industriales - Materiales y Estructuras - Modelos Numéricos), 17

  
  

  Abstract

  The OUTCOME Thermoplastic Upper Skin consortium is a European project framed within the Airframe ITD research platform of CleanSky2, funded by the EU's Horizon 2020 program. It is focused on developing, manufacturing, and validating a thermoplastic composite upper wing skin for future application in Airbus Defence and Space transport aircraft. The upper skin consists of a stiffened panel of approximately 4 meters in length, with six integrated stringers. These elements were joined through a co-consolidation process, where they were welded simultaneously with the tape layup of the skin using In-Situ Consolidation (ISC). The integrated stringers were manufactured in a previous stage using an oven consolidation process. The skin lamination was carried out through ISC using an automated tape laying equipment such as AFP MTorres, assisted by a laser and utilizing PEEK APC-2/AS4 material with a ¼" tow width. Throughout the project, a campaign of structural tests was conducted to obtain the mechanical properties and allowable values for the design of the outer wing box's upper skin. Detailed and subcomponent specimens (stiffened panels) were also designed, manufactured, and tested with the aim of validating the design, analysis methodology, manufacturing method, and quality control procedure. The activity will conclude at the end of the year with the ground structural testing of the wing box, of which the element is a part, completing the testing pyramid.

  Abstract
  The OUTCOME Thermoplastic Upper Skin consortium is a European project framed within the Airframe ITD research platform of CleanSky2, funded by the EU's Horizon 2020 program. [...]

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• Additive preforming technology applied to carbon-reinforced composites

  E. Hernández-Murillo, L. Palenzuela, C. Elizetxea, G. Guerrica-echevarría, R. Aguirresarobe, N. Aranburu, E. Murillo

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 8 - Fabricación y Aplicaciones Industriales - Materiales y Estructuras - Modelos Numéricos), 18

  
  

  Abstract

  Manufacturing composite materials by conventional methods is known to be costly as it requires many steps, equipment and tooling. The challenge this presents can benefit from the moldless approach and rapid, automated prototyping enabled by additive manufacturing. Today, additive technologies are changing the manufacturing processes of plastics and composites, allowing short series to be automated and scalable for adaptation to long series, always oriented to final part production. In addition, the mechanical limitations presented by 3D printing processes of polymeric materials have been enhanced by the reinforcement of short or continuous carbon and glass fibers, mainly. Moreover, the hybridization of additive technologies with conventional processes makes it possible to overcome their current limitations, taking advantage of many of their benefits and increasing the fields of application. In this context, the idea of developing a technology that allows obtaining intermediate parts or preforms with high geometric complexity, which require a subsequent process, such as resin transfer molding (RTM), that confers mechanical performance similar to that of composites. In this work, an alternative method of manufacturing carbon fiber reinforced preforms using an additive process based on Fused Fusion Deposition Modeling (FDM) is detailed, as well as the production of composites from these preforms. Thus, the 3D preform is manufactured from fiber filaments coated with a thermoplastic binder. Then, this preform is subjected to a thermosetting resin injection process in a mold to obtain the final composite. In summary, a new method of additive preforming in combined with RTM is proposed to manufacture carbon fiber reinforced polymer composites (CFRPC).

  Abstract
  Manufacturing composite materials by conventional methods is known to be costly as it requires many steps, equipment and tooling. The challenge this presents can benefit from [...]

  • 0
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• Design and manufacturing of thermoplastic curved fuselage panel for Large Passenger Aircraft

  I. Martín, K. Fernández, J. Cuenca, K. Muñoz, S. Anaya

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 8 - Fabricación y Aplicaciones Industriales - Materiales y Estructuras - Modelos Numéricos), 19

  
  

  Abstract

  Due to the huge interest of the aeronautic industry for finding new solutions in terms of processes and materials to improve performances and to reduce costs, thermoplastic composite materials appeared as an attractive solution. The high temperatures required for processing this kind of materials and the lack of knowledge in the associated manufacturing processes make their application to structural parts more complex compared to that of thermoset composite materials. The study presented here contains the design and manufacturing of a curved section of a fuselage reinforced with omega stringers and ‘Z’ curved frames. The requirements for designing were taken by considering a preliminary flat demo which was manufactured and tested. Following the manufacturing activities conducted with the flat demo, the stiffeners were obtained by hand lay-up and hot press forming, afterwards they were installed in a tooling with specific cavities and the skin was laminated on top. The lamination of the skin was conducted by using a gantry style machine from the Spanish supplier MTorres. The adhesion of the skin to the stiffeners was possible by increasing the temperature to melting point by using a diode laser. After laminating the skin, the whole demo was demolded and inspected by non-destructive testing, showing a good quality in terms of the skin consolidation and in the welding line with the stiffeners. This work was developed as part of LPA project (Large Passenger Aircraft) in the framework of the Clean Sky 2 JU program.

  Abstract
  Due to the huge interest of the aeronautic industry for finding new solutions in terms of processes and materials to improve performances and to reduce costs, thermoplastic [...]

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• 3D printing by direct ink writing of graphite electrodes using whey as sustainable binder

  P. Lagar*, R. Santamaría, C. Blanco, J. Menéndez, M. Montes-Morán, P. Rodríguez Lagar

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 8 - Fabricación y Aplicaciones Industriales - Materiales y Estructuras - Modelos Numéricos), 20

  
  

  Abstract

  Traditionally, electrodes are produced by coating slurries of porous carbon powders on thin metallic plates. With the development of additive manufacturing technologies, new production methods have been studied in the literature that are intended to the fabrication of 3D electrodes with geometries that offer advantages in terms of easing the different transport phenomena involved in electrochemical processes. However, the low mechanical strength of the 3D electrodes hampers their applicability. This study introduces a novel method for producing graphite/graphene oxide electrodes that possess adequate flexural strength. The proposed method involves using whey, a sustainable by-product of the dairy industry, as a binder. The electrodes are made by direct ink writing (a room temperature extrusion 3D printing technique) which allows the manufacture of 3D structures by overlapping layers of material filaments. By using this technique, electrodes with geometries tailored to satisfy the specific requirements of the application can be prepared. Specifically, we have developed electrodes for water splitting with complex geometries in which the active surface area is enhanced and that guarantee a quick release of the bubbles formed in the reaction, thus avoiding the problems related to mass transport associated to conventional, flat electrodes.

  Abstract
  Traditionally, electrodes are produced by coating slurries of porous carbon powders on thin metallic plates. With the development of additive manufacturing technologies, new [...]

  • 0
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• Experimental and numerical analysis of the response of a carbon fiber composite material to an explosion.

  R. del Cuvillo, M. Costas, V. Aune, T. Børvik, J. Artero, J. Pernas, J. López-Puente

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 8 - Fabricación y Aplicaciones Industriales - Materiales y Estructuras - Modelos Numéricos), 21

  
  

  Abstract

  The aeronautical industry, in its search for more weight-efficient solutions, increasingly uses composite materials due to their specific properties. However, these are vulnerable to loads perpendicular to their lamination plane. Due to these vulnerabilities, numerous studies have tried to evaluate the threat of different states of perpendicular loading, there are numerous studies of high and low velocity impacts of rigid projectiles, the impact of non-rigid projectiles such as birds, ice, etc. have also been studied. or rubber like that of a tire. However, the study of impulsive loads on composite materials is very scarce. In this work, a combined experimental/numerical study is presented to evaluate the response of a fabric-type CFRP to shock waves, representative of impulsive loads due to explosions. The experimental tests were carried out at the so-called 'SIMLab Shock Tube Facility (SSTF)', at the Norwegian University of Science and Technology (NTNU). Laminates were tested at different pressures to investigate their behavior from an elastic response to total failure. In addition, two high-speed cameras were used to obtain, with the 3D-DIC methodology, the displacement fields. In order to study the internal damage produced in the laminates, non-destructive ultrasonic inspection techniques were used. To reproduce the behavior of the laminates, a continuous damage model was used, which takes into account the intralaminar damages of the composite material such as fiber breakage. Interlaminar damage was modeled using cohesive surfaces.

  Abstract
  The aeronautical industry, in its search for more weight-efficient solutions, increasingly uses composite materials due to their specific properties. However, these are vulnerable [...]

  • 0
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• Automation of the dry fibre deposition process to manufacture structural parts for the automotive sector

  L. Carral, A. Gutierrez, L. Mera

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 8 - Fabricación y Aplicaciones Industriales - Materiales y Estructuras - Modelos Numéricos), 22

  
  

  Abstract

  In recent years, lightweight structures have gained importance due to increasingly stringent environmental legislations. This situation is especially critical for the transport sector and, especially, for the automotive sector where, in parallel, there is a strong competitiveness. In this context, it should be noted that traditionally manufacturing processes for structural composite materials involver high TAKT times, which has limited their implementation. Thus, the resin transfer molding manufacturing process and, more specifically, its recently developed thermoplastic version (TP-RTM) has been identified as a route with great potential for mass manufacturing. Within the framework of the European LEVIS project, the development of a suspension arm made entirely of composite materials has been studied. This study focuses on the development of the process window of the preforming stage, one of the most critical for the development of complex geometries. In this sense, automated taping technology has broken few years ago, allowing the improvement of robustness and productivity. Specifically, a wide range of materials has been studied and important parameters such as fibre deposition pressures and temperatures have been analysed. On the other hand, to optimize the TP-RTM, several aspects have been studied, such as viscosity of the resin, the curing cycle of the resin, the compatibility of the resin, the curing cycle of the resin with the dry fibre and the study of the optimal parameters for the resin injection.

  Abstract
  In recent years, lightweight structures have gained importance due to increasingly stringent environmental legislations. This situation is especially critical for the transport [...]

  • 0
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• Implementation of a void formation and transport computational framework with applicability to liquid composite moulding

  J. Machado, P. Simacek, S. Advani, P. Camanho, N. Correia

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 8 - Fabricación y Aplicaciones Industriales - Materiales y Estructuras - Modelos Numéricos), 23

  
  

  Abstract

  The inclusion of reliable void formation and transport models in process models for LCM is paramount to guarantee the reliability of the manufactured parts, since it allows the estimation of part in-situ void content after mould filling, as well as the estimation of the ideal bleeding time. The incorporation of void dynamics into mould filling simulations has traditionally been under the form of unsaturated flow, where a continuous saturation field is advected. However, these models lack the prediction of the morphological properties of voids, which are known to influence their mobility through the reinforcement, as well as the final part mechanical properties. Also, direct numerical simulation methodologies, which are fundamentally based on the Volume of Fluid (VoF) method, can provide void morphological data but are too computationally expensive to apply directly into an entire mould filling domain. Particle tracking methodologies have extensively been used in computational fluid dynamics (CFD), to solve problems in which the fluid flow carries solid particles, such as in sediment deposition. This methodology could prove to be a computationally efficient way to deal with the different void morphologies registered, both during void generation, as well as transport, since each void is taken as a discrete particle, thus possessing its own set of properties. As of today, mould filling simulation software do not encompass such a methodology to allow mould design optimization. This work discusses the implementation of such a methodology, envisioning a streamlined application into process design.

  Abstract
  The inclusion of reliable void formation and transport models in process models for LCM is paramount to guarantee the reliability of the manufactured parts, since it allows [...]

  • 1
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• Buckling of circular cylindrical shells under in-plane and/or pressure loads

  J. Herencia

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 8 - Fabricación y Aplicaciones Industriales - Materiales y Estructuras - Modelos Numéricos), 24

  
  

  Abstract

  This work presents a semi-analytical approach to calculate rapidly but accurately the buckling onset of metallic and composite circular cylindrical shells with various boundary conditions under in-plane and/or pressure loads by the Rayleigh-Ritz method. Results are compared with analytical solutions and detailed finite element models reported in the literature. The proposed approach allows a quick buckling analysis of circular cylindrical shells, which makes it an ideal candidate to be used as part of an optimization scheme and/or to reduce potentially the number of detailed finite element models employed in the early design phases.

  Abstract
  This work presents a semi-analytical approach to calculate rapidly but accurately the buckling onset of metallic and composite circular cylindrical shells with various boundary [...]

  • 0
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• Composite plate buckling. Best practices in Airbus Commercial

  A. Montes Salmeron

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 8 - Fabricación y Aplicaciones Industriales - Materiales y Estructuras - Modelos Numéricos), 25

  
  

  Abstract

  During the last 20 years computational progress has significantly increased the capacity to determine the behavior of structures under complex loading conditions through finite element models analysis. This computational power can be used to build complex detailed finite element models but also to resolve more complex equations which were not possible to be coded before. Accurate buckling prediction is still a key factor on optimized structural designs. The accurate determination of the onset of buckling is absolutely essential to determine the initial point of instability and the subsequent post-buckling capability. Determining if the buckling will lead to immediate failure or the loading will be able to be redistributed afterwards is a major point to be considered. Designing a structural component with loading redistribution capability optimize the weight and increase the accuracy, so is a key objective of designers on structural components like torque boxes or fuselage skin. During years Airbus has been focused on developing accurate buckling predictions from close form solutions to complex energy methods development. This paper aims to summarize the evolution of such methods with special emphasis in energy methods and the best practices followed in Airbus for development. On top a summary of potential room for improvement and further evolution will be proposed.

  Abstract
  During the last 20 years computational progress has significantly increased the capacity to determine the behavior of structures under complex loading conditions through finite [...]

  • 15
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• Análisis numérico del efecto de la velocidad de deformación en laminados CFRP tipo tejido con agujero

  J. Sereno, J. Pernas-Sánchez, J. Artero-Guerrero, J. Puente, J. Rodríguez Sereno

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 8 - Fabricación y Aplicaciones Industriales - Materiales y Estructuras - Modelos Numéricos), 26

  
  

  Abstract

  Eventualmente las estructuras aeronáuticas pueden estar sometidas a eventos de impactos como los que pueden ocurrir durante un aterrizaje de emergencia o un accidente aéreo. En estos sucesos es necesario poder predecir el comportamiento de las estructuras sometidas a procesos dinámicos para poder asegurar la seguridad e integridad de las mismas. Dado que en la actualidad una gran parte de las estructuras se realizan en materiales compuesto es necesario definir un sólido conocimiento de cómo éstos se comportan bajo cargas dinámicas o procesos a altas velocidades de deformación. Siendo el estudio de laminados compuestos de fibra de carbono (CFRP) a altas velocidades de deformación uno de los principales desafíos en la industria aeronáutica. Varios investigadores han estudiado el efecto de la velocidad de deformación en laminados CFRP de estructura tipo tejido mediante el sistema experimental de barras Hopkinson (Split Hopkinson Pressure Bar - SHPB). Sin embargo, la comunidad investigadora aún no ha llegado a un acuerdo para encontrar una metodología sólida que describa con precisión la respuesta ante elevadas velocidades de deformación de los laminados CFRP tipo tejido. Es más escaso aún el número de estudios acerca del efecto de agujeros en régimen dinámico para describir el efecto del factor de concentración de tensiones. Aunque muchos estudios han desarrollado simulaciones numéricas para analizar el proceso de fractura en CFRP basándose en las teorías de la mecánica de fractura, hay poca información sobre la dependencia de la velocidad de deformación en laminados de CFRP tipo tejido con agujero. En este trabajo, se propone un modelo constitutivo para describir el comportamiento mecánico de los laminados de tejido CFRP sometidos a compresión dinámica, incluyendo la dependencia de la velocidad de deformación. Finalmente, se ha realizado una modelización numérica utilizando el software Abaqus/Explicit de ensayos a compresión en muestras de laminados CFRP con agujeros, a diferentes velocidades de deformación (cuasi-estáticas y dinámicas) utilizando diferentes orientaciones de las fibras. Los resultados de las simulaciones han sido validados en base a los resultados de una campaña experimental.

  Abstract
  Eventualmente las estructuras aeronáuticas pueden estar sometidas a eventos de impactos como los que pueden ocurrir durante un aterrizaje de emergencia o un accidente [...]

  • 4
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• Analysis of composite beams using reduced order modeling

  R. Rubio, A. Ferrer, J. HERNÁNDEZ ORTEGA, X. Martinez

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 8 - Fabricación y Aplicaciones Industriales - Materiales y Estructuras - Modelos Numéricos), 27

  
  

  Abstract

  Beam-like components help to provide structural integrity in a wide range of applications. Initially made of alloys or natural materials such as wood, today’s technologies like pultrusion make possible the manufacturing of such components with composite materials providing good quality products with high performance to weight ratio. The anisotropic nature of composite materials, though, poses a challenging framework when numerically simulating them. This work presents the integration in standard Finite Element (FE) packages of a machine learning methodology that naturally captures the behaviour of composite materials: the multiscale method for periodic structures using domain decomposition and ECM-hyper reduction. The method provides a special type of finite element that can be assembled using FE libraries. However, the kinematics of this element may be described by more Degrees of Freedom (DoF) per node than most standard FE packages consider, hence implementing it is a non-trivial task. The strategy presented here tries to tackle the limitation by means of static condensation followed by a regression procedure. Periodic boundary conditions are employed for the extra DoFs while the regression consists in a polynomial on the logarithmic space. This paper focuses on the performance of the integrated beam element through the analysis of a pultruded omega profile whose anisotropy requires the use of complex models to accurately capture its mechanical behaviour. The agreement between the results obtained with the proposed model and those given by more complex formulations validates the methodology and enables its use in regular FE codes to characterize complex composite beam structures.

  Abstract
  Beam-like components help to provide structural integrity in a wide range of applications. Initially made of alloys or natural materials such as wood, today’s technologies [...]

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• Thermal induced stress analysis in type V CFRP pressure vessels for cryogenic applications. (Análisis de esfuerzos térmicos inducidos en recipientes a presión tipo V para aplicaciones criogénicas)

  P. Goncalves, B. Rocha, A. Arteiro, N. Rocha, R. Carvalho

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 8 - Fabricación y Aplicaciones Industriales - Materiales y Estructuras - Modelos Numéricos), 28

  
  

  Abstract

  During the manufacturing of thermoset-based Carbon Fiber Reinforced Polymers (CFRPs), micro-residual stresses are developed within the material due to the different chemical-thermal-mechanical properties of the fiber and the polymer. Considering cryogenic applications, the temperature change from ambient temperature to operating conditions (for example in liquid nitrogen which is at -196°C) involves a temperature change of more than 300°C considering curing temperature from manufacturing. This temperature change develops micro-residual stresses and ply residual stresses that could trigger premature transverse failure or micro-cracking, reducing the effective mechanical performance of the pressure vessel. In this work, a 3D finite element model of the CFRP pressure vessel is developed considering a discretization at meso-scale level, with the actual ply stack orientations and thickness profiles to study the thermo-mechanical residual stresses and the remaining pressure load carrying capacity at cryogenic conditions. The material model was calibrated with experiments on the unidirectional composite at ambient temperature, and cryogenic temperature. The results show that the thermo-mechanical residual stresses can achieve more than 50% of the ply transverse strength, pressure load carrying capacity is reduced and premature transverse failure can be triggered if these effects are not considered during design. Durante la fabricación de polímeros reforzados con fibra de carbono (CFRP) termoestables, se producen esfuerzos micro residuales dentro del material debido a la disimilitud entre las propiedades termo mecánicas y químicas entre la fibra y el polímero. En aplicaciones criogénicas, la variación de temperatura desde la temperatura ambiente hasta la temperatura de operación, donde por ejemplo el nitrógeno líquido que está a -196°C, implica un cambio de temperatura de más de 300°C considerando la temperatura de curado. Este cambio de temperatura desarrolla tensiones micro residuales, y tensiones residuales en las láminas que pueden activar prematuramente mecanismos de falla transversal o micro fisuras, reduciendo el rendimiento efectivo del recipiente a presión. En este trabajo se desarrolló un modelo 3D utilizando elementos finitos del recipiente a presión de CFRP, considerando una discretización a nivel de meso-escala, con las orientaciones reales de las láminas y de los perfiles de espesores, para estudiar las tensiones residuales termo-mecánicas y la resistencia remanente en condiciones criogénicas bajo presión interna. El modelo de material se calibró con ensayos experimentales del material compuesto unidireccional a temperatura ambiente y a temperatura criogénica. Los resultados muestran que las tensiones residuales termomecánicas pueden alcanzar más del 50% de la resistencia transversal de la lámina, y es posible obtener una falla transversal prematura en la lamina del compuesto si no se tienen en cuenta estos efectos durante el diseño.

  Abstract
  During the manufacturing of thermoset-based Carbon Fiber Reinforced Polymers (CFRPs), micro-residual stresses are developed within the material due to the different chemical-thermal-mechanical [...]

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• On the influence of ply thickness and staking sequence in the Free-edge effect

  J. Martin Beato, . J.M.González-Cantero, . S.Rebollo, . D.Meizoso, . J.M.Blanco, . J.A.Rodriguez, . A.torres

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 8 - Fabricación y Aplicaciones Industriales - Materiales y Estructuras - Modelos Numéricos), 29

  
  

  Abstract

  The edge effect in composite materials is a phenomenon associated with the anisotropy of these materials, generating interlaminar shear and tensile stresses and delaminations at the edges of the panels. This fact was studied by Pipes and Pagano in 1973, obtaining a solution to solve the problem with certain application limitations. This document aims to show a solution to the problem based on the studies carried out since then and use a method capable of evaluating these interlaminar forces, as well as a preliminary failure criterion associated with it. Different parameters can be evaluated such as the thickness of the sheets, the combination of materials or different laminate sequences.

  Abstract
  The edge effect in composite materials is a phenomenon associated with the anisotropy of these materials, generating interlaminar shear and tensile stresses and delaminations [...]

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• Machining of Hybrid Composite Materials

  M. Rodriguez, M. Freitas, A. Marques, A. Jesus, S. Villa

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 8 - Fabricación y Aplicaciones Industriales - Materiales y Estructuras - Modelos Numéricos), 32

  
  

  Abstract

  Composite materials have been having an increasing importance in the industry. Their high specific properties and their high flexibility that allows tailoring materials that suit the needs of practically every project, have been leading to a growth in the demand of this kind of materials. Fiber-Metal Laminates have an established usage on the aeronautic industry and lately have been subject of research by the automotive industry. Since composite manufacturing methods allow the obtention of components with their final geometry, drilling is the most used machining operation in the machining of composites. Drilling of composites is very demanding from the tools point of view, with very high wear rates and several defects can occur to the workpiece like delamination, fiber pull-outs, burrs and matrix degradation. When combined with a metal, additional challenges appear in drilling these materials such as loads of different magnitudes during a single operation and surface defects on the interface because of chip removal. Orbital drilling is seen as a promising alternative to conventional drilling, presenting several advantages that result in holes with higher quality. Given the interest the automotive industry has been showing in fiber-metal laminates constituted by steel and carbon fiber reinforced plastics (CFRP) and due to the lack of information regarding drilling of this combination of materials, the aim of this work was to evaluate the influence of the machining parameters in the quality of holes obtained by orbital drilling. A full factorial design of experiments was done and the influence of the parameters was then evaluated by means of an Analysis of Variance (ANOVA).

  Abstract
  Composite materials have been having an increasing importance in the industry. Their high specific properties and their high flexibility that allows tailoring materials that [...]

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• Robotic additive manufacturing of continuous carbon fiber thermoplastic composites

  A. Pedreira, E. Rodriguez, P. Rodriguez, A. Rodrigez

  Materiales Compuestos (2025). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 8 - Fabricación y Aplicaciones Industriales - Materiales y Estructuras - Modelos Numéricos), 33

  
  

  Abstract

  Fused Filament Fabrication (FFF) technology is one of the most popular 3D printing processes and interest in direct manufacturing of functional parts is growing. For this reason, both techniques and feedstock materials require improvements to meet the mechanical requirements of load-bearing components. In this sense, this work is focused on the robotized FFF process of continuous carbon fiber thermoplastic composites. It includes an analysis and comparison of the developed FFF robotic 3D printing process with the conventional process, as well as the development of robotic 3D printing equipment for the manufacture of continuous fiber reinforced composites and the characterization of the printing process developed to print the new filaments based on the thermoplastic matrix and reinforced with continuous carbon fiber. The material was analysed by microscopic analysis, and the manufacturing specimens were characterized by mechanical tensile and flexural tests.

  Abstract
  Fused Filament Fabrication (FFF) technology is one of the most popular 3D printing processes and interest in direct manufacturing of functional parts is growing. For this [...]

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