Documents published in 2025 : Scipedia

Fire Hazards Caused by Equipment Used in Offshore Oil and Gas Operations: Prescriptive vs. Goal-Oriented Legislation
D. Brkić

Fire (2025). https://www.mdpi.com/2571-6255/8/1/29

Abstract
Тhis article offers a concise overview of the best practices for safety in offshore oil and gas operations, focusing on the risks associated with various types of equipment, particularly on the risk of fire. It identifies specific machinery and systems that could pose hazards, assesses their potential impact on safety, and explores conditions that may lead to accidents. Some of the largest accidents were analyzed for their associations with fire hazards and specific equipment. Two primary regulatory approaches to offshore safety are examined: the prescriptive approach in the United States (US) and the goal-oriented approach in Europe. The prescriptive approach mandates strict compliance with specific regulations, while in the goal-oriented approach a failure to adhere to recognized best practices can result in legal accountability for negligence, especially concerning human life and environmental protection. This article also reviews achievements in safety through the efforts of regulatory authorities, industry collaborations, technical standards, and risk assessments, with particular attention given to the status of Mobile Offshore Drilling Units (MODUs). Contrary to common belief, the most frequent types of accidents are not those involving a fire/explosion caused by the failure of the Blowout Preventer (BOP) after a well problem has already started. Following analysis, it can be concluded that the most frequent type of accident typically occurs without fire and is due to material fatigue. This can result in the collapse of the facility, capsizing of the platform, and loss of buoyancy of mobile units, particularly in bad weather or during towing operations. It cannot be concluded that accidents can be more efficiently prevented under a specific type of safety regime, whether prescriptive or goal-oriented.
Abstract
Тhis article offers a concise overview of the best practices for safety in offshore oil and gas operations, focusing on the risks associated with various types of equipment, [...]
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Serbian energy sector in the global political landscape amid the Russia‑Ukraine war: a focus on perspectives of integration into the European Union
D. Brkić

Discover Energy (2024). https://link.springer.com/article/10.1007/s43937-024-00056-2

Abstract
This article consists of two main parts, both in relation to Serbia’s accession to the European Union EU in relation to its energy sector: (1) Political and policy issues, and (2) Energy production, consumption and pricing. Each is heavily influenced by the Russia-Ukraine War. Political issues are primarily related to Kosovo, which unilaterally declared independence from Serbia. Regarding supply, Serbia’s energy sector is affected unevenly: while electricity production remains self-sufficient, shortages in oil and gas necessitate imports. Natural gas imports, primarily from Russia, now bypass Ukraine, aided by the new Turk Stream pipeline via Black Sea and also new EU-funded interconnector with Bulgaria. Newly introduced EU sanctions restrict Russian crude oil imports especially via maritime routes, but Russian influence still dominates domestic refineries and hydrocarbon extraction. Serbia’s heavy reliance on environmentally unfriendly lignite conflicts with EU renewable goals, but on the other hand protests against small hydropower projects for capturing rivers in pipes are frequent nowadays. Recent issues in the largest thermal power plant led to costly temporary imports. Despite challenges, Serbia navigates a complex energy landscape, balancing geopolitical realities with domestic and EU objectives while addressing environmental concerns, energy security and its national interest.
Abstract
This article consists of two main parts, both in relation to Serbia’s accession to the European Union EU in relation to its energy sector: (1) Political and policy issues, [...]
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A microstructure-integrated acoustoplastic constitutive model for ultrasonic-assisted machining of Ti6Al4V alloy
H. Bakhshan, E. Oñate, J. Carbonell

CIRP Journal of Manufacturing Science and Technology (2025). Vol. 57, 14-31

Abstract
The ultrasonic-assisted machining (UAM) technology, compared to conventional machining (CM), has been proven to be an effective method for machining the difficult-to-cut Ti6Al4V alloy (TC4). In the UAM process, the evolution mechanism of microstructure and hardness directly influences the material behavior and consequently, mechanical response, which remains unrevealed from a computational perspective. To address this, in this study, we present a developed modeling technique that combines the Particle Finite Element Method (PFEM) with incremental homogeneous field distributions in a coupled manner to effectively predict the macro and micro response of the material in both CM and UAM processes. First, the evolution of microstructural parameters, including immobile dislocation density (IDD) and mobile dislocation density (MDD), dynamic recrystallization (DRx) grain size, and hardness, is incrementally developed and incorporated into the PFEM using internal state variables. The Johnson–Mehl–Avrami–Kolmogorov (JMAK) model and Hall–Petch equation are employed for predicting grain size and hardness, respectively. Second, A microstructure-integrated acoustoplastic constitutive model is developed based on a modified Johnson–Cook (JC) model and average grain size (AGS) predictions dependent on ultrasonic vibration (UV) parameters. The proposed model is embedded into the PFEM to conduct a thermo-mechanical analysis capable of capturing the TC4 response, particularly in terms of serrated chip formation during CM and UAM processes. The model’s validity is checked through comparison with available experimental results in terms of chip shapes. Lastly, the predicted AGS and hardness in serrated chips and machined surface are compared with experimental data, showing good agreement. This suggests that the proposed acoustoplastic constitutive model, coupled with microstructure and UV parameters, can reliably analyze the CM and UAM processes of the TC4.
Abstract
The ultrasonic-assisted machining (UAM) technology, compared to conventional machining (CM), has been proven to be an effective method for machining the difficult-to-cut Ti6Al4V [...]
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Enhancing Robotic Interaction: A Fractional-Order Impedance Control Strategy to Mitigate Overshooting and Improve Tracking in Dynamic Environments
H. Cao

Papers Repository of the International Centre for Numerical Methods in Engineering (CIMNE) (2025). 1

Abstract
This research investigates the difficulties associated with transient overshooting, sluggish tracking responses, and inadequate steady-state accuracy that occur during the dynamic interactions between robotic systems and their physical environments. To tackle these challenges, a fractional-order impedance control strategy for robotic systems is proposed. An initial evaluation of existing integer-order impedance control methods indicates that these approaches depend on modifications to the update rate and adjustments to the elasticity parameter to suit various tasks. In light of these constraints, this study presents a more adaptable fractional-order impedance control framework. By utilizing the intrinsic characteristics of fractional-order impedance, the gain coefficients are designed to enable the mapping of fractional-order impedance to integer-order impedance, thereby improving computational efficiency and practical applicability. Additionally, certain beneficial aspects of high integer-order impedance control are incorporated into the fractional-order impedance to enhance overall performance, with clearly defined boundaries for dynamic adjustments. Simulation results indicate that the proposed fractional-order impedance significantly diminishes the peak contact force overshoot during contact and effectively reduces the system's unstable oscillatory behaviours. This approach is particularly advantageous for applications in which robots must function and interact within dynamic and uncertain environments.
Abstract
This research investigates the difficulties associated with transient overshooting, sluggish tracking responses, and inadequate steady-state accuracy that occur during the [...]
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CONTRIBUCIÓN DE LA SOCICT+EDUNIV A LA SOCIALIZACIÓN DEL CONOCIMIENTO ACADÉMICO
R. Torricella Morales

Educa - UMCH (2025). N° 1

Abstract
Las Universidades cubanas disponen de repositorios institucionales para el auto-archivo de sus documentos académicos y de bibliotecas digitales, para la publicación de sus libros. Sin embargo, ni los repositorios, ni las bibliotecas digitales contribuyen, de forma significativa, a la Socialización del Conocimiento Académico en el ámbito internacional: la cantidad de descargas y consultas internacionales están por debajo de lo esperado a partir de la calidad de estos contenidos. Para solucionar esta situación, EDUNIV+SOCICT edita y publica documentos cubanos en en la Biblioteca Virtual Académica en Español eLibro. Se evaluó el USO (consultas + copias + descargas + usuarios) de una selección de libros cubanos disponibles eLibro. Los principales resultados alcanzados son: durante los años 2022-2023, los 779 títulos cubanos evaluados, alcanzaron 6.663.425 de USOS, mientras que en el período de enero 2024 a octubre 2020, recibieron 2.655.691 USOS. Si comparamos estos valores con los USOS de los 150 mil títulos disponibles en eLibro, 897.551.615 y 296.474.965 respectivamente, se puede afirmar que EDUNIV-SOCICT, con la edición y publicación en eLibro, contribuye a Socializar el Conocimiento académico cubano . En el presente trabajo se evaluaron los USOS de los documentos cubanos publicados en eLibro mediante, el indicador Altmétrico, Índice Wally. Se presentan tablas con la información de los títulos, autores y editoriales con los valores del índice Wally >= 0,80 (Primer cuartil Q1). Se recomienda utilizar esta información para estimular a los profesores e investigadores cubanos a publicar sus manuscritos docentes con las editoriales universitarias.
Abstract
Las Universidades cubanas disponen de repositorios institucionales para el auto-archivo de sus documentos académicos y de bibliotecas digitales, para la publicación [...]
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Fatigue delamination damage analysis in composite materials through a rule of mixtures approach
A. Taherzadeh-Fard, S. Jiménez, A. Cornejo Velázquez, E. Oñate, L. Barbu

Composite Structures (2025). Vol. 351, 118613

Abstract
The present study investigates delamination damage initiation and propagation within a homogenization theory of mixtures, using the concept of virtual layers and virtual interfaces. It eliminates spatial discretization of layers, introducing a resultant damage variable to capture structure’s bulk response under both monotonic and cyclic loads. Fatigue-induced deterioration is classified into sub-critical, critical, and over-critical stages based on interfacial stresses. Calibration is conducted employing the widely-available Wöhler curves for each loading mode independently. An advance-in-time strategy is included in the model to enhance the simulation speed. The reliability of the approach is assessed for crack initiation and propagation separately through standard test coupons, showing good correlation with experimental data in mode I, mode II, and mixed-mode loading conditions. Depending on the calibration procedure adopted, the model is applicable to a wide range of stress ratios. In addition, it could be integrated into any standard finite element framework using the desired number of elements through the thickness regardless of the physical amount of layers. This allows easy modification of stacking sequences or the number of layers within the constitutive law without mesh structure changes, facilitating simulation of large-scale composite laminates with minimal accuracy loss and reduced computational costs.
Abstract
The present study investigates delamination damage initiation and propagation within a homogenization theory of mixtures, using the concept of virtual layers and virtual interfaces. [...]
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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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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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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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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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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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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 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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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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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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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 [...]
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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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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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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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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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