Documents published in 2022 : Scipedia

NA-TECH EVENTS IN THE COASTAL REGION OF SÃO PAULO, BRAZIL: DATA AND FREQUENCY
J. Xavier, W. Junior

RIDNAIC (2022). Vol. 22, 3

Abstract
The scientific literature on events involving the loss of containment of hazardous materials due to a natural event (known as na-tech events) is recent and limited in Brazil. Evidence was sought of the occurrence of these events in the coastal region of the state of São Paulo. The study identified fifteen na-tech events between 1940 and 2015, and showed that the events predominantly affected bodies of water. A method was then proposed to estimate the frequency of these events, relativizing them to the number of companies that generated them. Relativization allows the quantitative comparison among locations with different numbers of companies and the transfer of the estimated frequency among locations. The method also allows attributing less uncertain frequency estimates to na-tech accident hypotheses, favoring risk-based decisions. Consistent databases combined with the method allow the construction of na-tech hypotheses appropriate to the location during a quantitative risk assessment of an industrial facility.
Abstract
The scientific literature on events involving the loss of containment of hazardous materials due to a natural event (known as na-tech events) is recent and limited in Brazil. [...]
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DYNAMIC SEISMIC RESPONSE OF LA MISSION BRIDGE IN BAJA CALIFORNIA, MÉXICO
S. Hoon, C. Huerta-López, A. García-Gastélum

RIDNAIC (2022). Vol. 22, 2

Abstract
The analytical and experimental seismic response of La Mission Bridge, and the site sub-surface characterization on its neighborhood is presented in this paper. SAP 2000 (Structural Analysis Program) was used to model and characterize numerically the expected response of the bridge in terms of their vibration natural frequencies and maximum displacement. It was also generated the scenario of the bridge response upon strong motion. In both cases, ambient vibration measurements were used for the experimental studies. The stiffness matrix method was used for the analytical study (forward modeling) of wave propagation in layered media. The relevant characteristics of the results are next succinctly described: For the bridge: the theoretical fundamental frequency of vibration was 3.10 Hz., and the estimated experimental fundamental vibration frequency was 3.30 Hz. For the site characterization, our results are described starting at the north end of the bridge going through its south end: (i) The site S1_2, which is the site where the soil was artificially compacted, has a dominant frequency of 2.5 Hz and an average shear wave velocity of 195 m/s. (ii) For sites S3_1 and S2_4, the dominant frequency was 1.5 Hz and the average shear wave velocity was 115 m/s and 123 m/s, respectively. (iii) Site S2_2, the dominant frequency was 3.5 Hz and an average shear wave velocity 275 m/s. (iv) Site S2_5, in this site two clear peaks at frequencies of 1.5 and 3.75 Hz were observed, regarding to the average shear wave velocity it was 128 m/s. (v) Site S2_3, the dominant frequency was 4.0 Hz and the average shear wave velocity was 346 m/s. All the experimental sites were in soils at natural conditions, but the site S1_2, which was artificially compacted. The soil characteristics along the 163 m length of the bridge, clearly shows a rigidity change of the soil sub-surface conditions. That condition is an indication that different amplifications of the ground response will probably be experienced, being in the range of the 4.0 Hz at the south-end side of the bridge, and 1.5 Hz on the portion of the north-end of the bridge. In no case the fundamental vibration frequency of the bridge matches the fundamental vibration frequency of the ground surface. However, they are somehow no too far apart each other.
Abstract
The analytical and experimental seismic response of La Mission Bridge, and the site sub-surface characterization on its neighborhood is presented in this paper. SAP 2000 (Structural [...]
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STATISTICAL EXPLORATION OF SEISMIC DATA IN PUERTO RICO FROM DECEMBER 2019 TO JANUARY 2021
S. Huanca, R. Trespalacios, Z. Acevedo, D. Alizo, A. Nieves, C. Isaza, M. Ríos

RIDNAIC (2022). Vol. 22, 1

Abstract
In December 2019, Puerto Rico experienced an increment in seismic activity, especially in the South and Southwestern regions of the island. The hundreds of buildings and homes damaged or destroyed prompted the hasty installation of multiple shelters and showed the little preparedness of the municipalities of the island to face emergencies of this kind and magnitude. The municipalities of Guánica and Guayanilla reported the largest impacts in terms of number and magnitudes of earthquakes. Surrounding municipalities, however, were also importantly affected. Despite a decrease in seismic activity in February 2020, event occurrences and magnitudes continued to fluctuate. The COVID-19 pandemic, due to its global reach, eclipsed many other emergencies including that of the seismic activity in the island. This study provides data and statistical summaries on this activity from the first week of December 2019 until the second week of 2021 that may be useful for future researchers in the area of seismic engineering and related fields.
Abstract
In December 2019, Puerto Rico experienced an increment in seismic activity, especially in the South and Southwestern regions of the island. The hundreds of buildings and homes [...]
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A Taylor-Galerkin method for the use of finite elements in a nonlinear problem for the numerical modeling of a new Chemo-Fluid oscillator
I. Alvarez

Revista Mexicana de Métodos Numéricos (2022). Vol. 6, 2

Abstract
In this work, a finite element scheme is proposed using a method of Euler-Taylor-Galerkin described in Páez et al. (2016), for a non-linear model which describes the behavior of a new chemo-fluidic oscillator, Donea (1984). This model is expressed by the coupling of an ordinary differential equation describing the hydrogel dynamics, the non-linear transport equation and an auxiliary equation determining the flux volume. The numerical solution is constructed by taking a semi-discretization in time of the transport equation, employing forward-time Taylor series expansions including time derivatives of second order and third order, avoiding instabilities problems. In this semi discrete equation, the spatial variable is approximated by the finite element formulation according to Galerkin. Some simulations are carried out taking different initial conditions for the concentration of the hydrogel. The numerical results describe the oscillatory behavior of the system as in Donea (1984), where MatLab tools are used as black box.
Abstract
In this work, a finite element scheme is proposed using a method of Euler-Taylor-Galerkin described in Páez et al. (2016), for a non-linear model which describes the [...]
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Structural design and performance analysis of sliding double-layer water injection distributor
X. Zhou, H. *, Z. Zhao, X. Zhang, X. Ji

Rev. int. métodos numér. cálc. diseño ing. (2022). Vol. 38, (4), 40

Abstract
Taking the double-layer water injection well and one graded water distributor could regulate two layers as the design and research goal, the sliding double-layer water injection distributor was designed by using the forward and reverse rotation of the driving motor to control the opening and closing of the two nozzles. The flow field of the two flow channels under different opening was analyzed by FLUENT software. The research shows that when the opening of the nozzle was less than 10mm, the maximum flow rate decreases rapidly, and when the opening exceeds 10mm, it decreases slowly. The mathematical models of flow pressure, flow velocity, and nozzle opening were obtained by data analysis and fitting. Finally, the kinematics simulation was carried out by AAMS, and the maximum friction force borne by each sealing in the movement process was obtained. The maximum torque borne in the movement process was 120.5N·m, which was less than the rated torque. The supporting motor could meet the design requirements.
Abstract
Taking the double-layer water injection well and one graded water distributor could regulate two layers as the design and research goal, the sliding double-layer water injection [...]
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ARTIFICIAL INTELLIGENCE APPLIED TO ADVERSE EVENT INFORMATION AND DRUG USE IN COLOMBIA
J. Pérez-Agudelo, S. Zuluaga-Dávila, P. Villegas-Jaramillo, D. Vélez-Giraldo, A. Buitrago-Ceballos, F. Grisales-Olmos, D. Mesa-Muñoz, Y. Caicedo-Palacios

Collection of Articles on Pharmacology, Toxicology and Pharmaceutics (2022). 1

Abstract
Artificial intelligence is a broad branch of computer science that enables the creation of analysis pathways that mimic human intelligence; it is a set of adaptive tools that can be used to predict outcomes from biological and clinical data. Artificial intelligence models have the potential to improve the efficiency of healthcare by integrating information including adverse drug events. Objective. To apply artificial intelligence techniques to adverse event and medication use information reported for the Colombian population. Methodology. Non-interventional research, with an analytical and retrospective component. The methods included data science mediated by artificial intelligence techniques. Study population: patients with national adverse event reporting between 2017 and 2019 available in the Colombia open data platform. Results. Female sex had a representation of 59.65% of the adverse events reported. The largest number of patients presented an outcome or exit type "recovered resolved" in 40.4%. The most common route of administration was the oral route (27.85%). The artificial intelligence algorithm allowed predictions close to 90% regarding recovery from an adverse reaction. Conclusion. The inclusion of artificial intelligence for the analysis of the variables: gender, adverse reaction recovery, route of administration, mechanism of the reaction, types of ADR and age of onset, allows the creation of a predictive tool that anticipates the presentation of possible outcomes related to the prescription of a drug.
Abstract
Artificial intelligence is a broad branch of computer science that enables the creation of analysis pathways that mimic human intelligence; it is a set of adaptive tools that [...]
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Influence of residual stress models prescribed in design codes for steel I-section behavior
Í. Lemes, J. Silva, E. Batelo, R. Silveira

Rev. int. métodos numér. cálc. diseño ing. (2022). Vol. 38, (4), 37

Abstract
Non-uniform cooling of steel cross-sections during the manufacturing process generates a state of residual stresses in the cross-section. Design codes describe the distribution of these stresses in different ways. This work aims to numerically investigate the influence of these models on the behavior of bare steel and steel-concrete composite sections by the curves: flexural stiffness-bending moment, moment-curvature and yield curves (initial and full yield). These procedures are important for the study of the simplified curves used in some methodologies of the refined plastic hinge method (RPHM) analysis. The study will use the strain compatibility method (SCM), where, if the axial strain of the cross-section point is known, the section stiffness is obtained using the tangential Young's modulus derived from the materials constitutive relationship. A fiber discretization algorithm is applied and the residual stresses are explicitly inserted into the fibers automatically. The methodology was calibrated using the moment-curvature relationship and the flexural stiffness-bending moment curve. These results were numerically stable and good convergence with literature data was obtained. In general, the residual stress model of the American standard (AISC, 2016) defines a larger elastic region within the interaction diagrams then European model (CEN, 2005). The results obtained showed that the initial yield curves for steel I-sections under minor axis bending require revision for application to RPHM, mainly due to the loss of symmetry in relation to the ''M'' axis in the normal force-bending moment (''NM'') interaction diagram.
Abstract
Non-uniform cooling of steel cross-sections during the manufacturing process generates a state of residual stresses in the cross-section. Design codes describe the distribution [...]
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D6.2 (WP6): Report on monitoring the project developments
E. Sanz, A. Haidar, P. Alonso

prodPhD OA (2022). 11

Abstract
Deliverable D6.2, ‘Report on monitoring the project developments’, aims to monitor the mid-term progress of the prodPhD project. This deliverable monitors the Key Performance Indicators (KPIs) of the actions in each work package of the project and provides an overall assessment of the results of each pilot action. KPI monitoring was based on the descriptive and evaluative operationalization of the KPIs in D6.1. However, the KPIs were initially not assigned specifically to individual work packages; the monitoring was therefore divided into two dimensions. First, the individual work packages were monitored in terms of ‘overall assessment’, where the partners reported the objectives of the work package, partners involved, discrepancies between intended and actual impact, modifications of plan, and progress plan. Second, the KPIs corresponding to each work package were monitored by the leader of each work package in line with their operationalization in D6.1. This mid-term monitoring of the progress of the prodPhD project shows that the implemented activities thus far meet their corresponding KPIs. In addition, this deliverable also provides an overall assessment of each Work Package (WP). Both the KPI monitoring and the overall assessment of each WP show the activities completed thus far meet their targets and, hence, the prodPhD project is on track to deliver optimal outcomes to meet its aims.
Abstract
Deliverable D6.2, ‘Report on monitoring the project developments’, aims to monitor the mid-term progress of the prodPhD project. This deliverable monitors the [...]
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D5.1 (WP5): Definition of the demonstration actions
C. García, E. Sanz, C. Soriano

prodPhD OA (2022). 10

Abstract
The objective of this document is to describe the tasks carried out in task 5.1 of prodPhD project, which is devoted to design the demonstration actions to be carried out on the prodPhD Online Training Environment. The document first introduces briefly the content and organization of the training modules in the training environment. Then, it presents the supervising team, introduces the procedure for selection of candidates for the demonstration actions, the pre-demonstration training sessions, the technical support and feedback mechanism and the monitoring and postdemonstration feedback mechanisms. Finally, the development of the demonstration actions is described.
Abstract
The objective of this document is to describe the tasks carried out in task 5.1 of prodPhD project, which is devoted to design the demonstration actions to be carried out [...]
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D4.1 (WP4): prodPhD microsite at Scipedia.com
C. García, J. García-Espinosa

prodPhD OA (2022). 9

Abstract
The objective of this document is to describe the tasks carried out in the frame of WP4 to develop a microsite in the platform Scipedia.com. This microsite enjoys the main capabilities of the open science platform Scipedia.com, and provide the framework to implement the prodPhD Online Training Environment, which will be customized to accomplish the project specific requirements.
Abstract
The objective of this document is to describe the tasks carried out in the frame of WP4 to develop a microsite in the platform Scipedia.com. This microsite enjoys the main [...]
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D3.1 (WP3) Definition of the training methodology
T. Bao, E. Sanz, C. García

prodPhD OA (2022). 8

Abstract
This document presents the educational methodology aimed at providing PhD candidates with the necessary knowledge and skills to start and run their business, be they aspiring or confirming entrepreneurs. It addresses the way the training should be done, the training programme content in terms of ‘training pills’ and for each one, specify the rationale, the intended learning outcomes and the content, and suggest the activities to be undertaken, the duration and additional information sources
Abstract
This document presents the educational methodology aimed at providing PhD candidates with the necessary knowledge and skills to start and run their business, be they aspiring [...]
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D7.3 (WP7): Events
J. García-Espinosa

prodPhD OA (2023). 6

Abstract
This document contains a list of the different events (conferences, seminars, webinars and workshops) which are organised by the project. This document will be updated and re-submitted at each reporting period.
Abstract
This document contains a list of the different events (conferences, seminars, webinars and workshops) which are organised by the project. This document will be updated and [...]
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D2.2 (WP2): Needs and requirements analysis
E. Sanz, M. Lascurain, A. Serrano, A. Haidar, P. Alonso

prodPhD OA (2022). 2

Abstract
The prodPhD project aims to address the challenging problem of introducing entrepreneurship training in PhD programmes regardless of discipline. The prodPhD project will create the necessary teaching methodologies and the platform for applying them. The project consists of a consortium of four organizations from across Europe. The main objective of the prodPhD project is to implement innovative social network-based methodologies for teaching and learning entrepreneurship in PhD programmes. The multidisciplinary teaching and learning methodologies will enable entrepreneurship education to be introduced into any PhD programme, providing students with the knowledge, skills, and motivation to engage in entrepreneurial activities. The methodology will be conceived to develop experiential knowledge, involving academics, entrepreneurship experts, and mentors in its development and implementation. Besides, the exchange of experience, competences, and approaches facilitated by social networking will pave the way to crowdsourcing new ideas, improving training methodologies, and stimulating academics’ entrepreneurial skills
Abstract
The prodPhD project aims to address the challenging problem of introducing entrepreneurship training in PhD programmes regardless of discipline. The prodPhD project [...]
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Hydraulic Losses in Systems of Conduits with Flow from Laminar to Fully Turbulent: A New Symbolic Regression Formulation
M. Milošević, D. Brkić, P. Praks, D. Litričin, Z. Stajić

Axioms (2022). Milošević, Marko, Dejan Brkić, Pavel Praks, Dragan Litričin, and Zoran Stajić. 2022. "Hydraulic Losses in Systems of Conduits with Flow from Laminar to Fully Turbulent: A New Symbolic Regression Formulation" Axioms 11, no. 5: 198. https://doi.org/10.3390/axioms11050198

Abstract
Separate flow friction formulations for laminar and turbulent regimes of flow through pipes are in common use in engineering practice. However, variation of different parameters in a system of conduits during conveying of fluids can cause changes in flow pattern from laminar to fully turbulent and vice versa. Because of that, it is useful to unify formulations for laminar and turbulent hydraulic regimes in one single coherent equation. In addition to a physical interpretation of hydraulic friction, this communication gives a short overview of already available Darcy’s flow friction formulations for both laminar and turbulent flow and additionally includes two simple completely new approximations based on symbolic regression.
Abstract
Separate flow friction formulations for laminar and turbulent regimes of flow through pipes are in common use in engineering practice. However, variation of different parameters [...]
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Anti-buckling device for biaxial testing with cruciform specimens
M. Moreno, S. Muñoz

Materiales Compuestos (2022). Vol. 05 - Comunicaciones Matcomp19 (2021), (Núm. 2 - Caracterización analítica, numérica y experimental de los materiales compuestos. Materiales multifuncionales. Comportamiento de componentes estructurales.), 57

Abstract
The use of an anti-buckling device is proposed to avoid the appearance of undesired instabilities during biaxial testing with cruciform specimens in which the compressive loads are applied directly on the arms of the sample by means of compression plates. The device consists on a cross-shaped accessory that restricts out-of-plane displacements and a L-shaped support that forces the alignment of the fixture, the specimen and the testing machine. In addition, recommendations about the test methodology and the conditioning of the cruciform sample are given. For this purpose, analytical and numerical studies are developed to design the experiments and to describe both the global buckling of the cruciform specimen and the local instability of the central region subjected to biaxial loading. The risk of instability in the arms of the sample is reduced under tension-compression and compression-compression loading cases whenever the device is used, ensuring that the results are not affected by premature buckling of the specimen and favoring the appearance of appropriate failure modes.
Abstract
The use of an anti-buckling device is proposed to avoid the appearance of undesired instabilities during biaxial testing with cruciform specimens in which the compressive [...]
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Synergistic effects of tubular halloysite clay and zirconium phosphate on thermal behavior of intumescent coating for structural steel
Y. Lee, F. Ahmad, S. Kabir, P. Masset, E. Oñate, G. Yeoh

Journal of Materials Research and Technology (2022). Vol. 18, pp. 4456-4469

Abstract
Zirconium phosphate (ZrP) recently introduced in intumescent fire protective coating has shown improvement in developing ceramic layer. The tubular halloysite clay (THC) due to its unique molecular structure can be combined with ZrP to enhance fire resistance by developing a strong silica network on the char surface. This study is aimed to investigate the synergistic effects of tubular halloysite clay and zirconium phosphate fillers to improve the thermal performance of the intumescent coating. The control coating formulation and a range of coating formulations using a combination of weight percentage of THC and ZrP were developed to study the influences of fillers on fire performance. The char expansion and fire resistance tests of the coatings were conducted using furnace fire test and Lab scale fire jet. Thermal stability of the coating was determined by TGA and char was characterized by FESEM, XRD, FTIR and XPS. Water-resistance test of the coating was performed according to ASTM D-870. Results showed that the reinforcement of THC-ZrP showed promising improvement on the performance of IFC and substrate temperature was far below the critical temperature, 550 °C. Sample HZ 5 showed the least backside steel substrate temperature of 219 °C. Expansion rate of char was found reduced with the addition of THC but improved the char compactness. The addition of THC and ZrP in IFC improved 18% fire resistance performance and 5% residual wt. Of char. Char morphology showed silica network, XRD and FTIR confirmed the presence of silicon. Water absorption test showed 95% less water absorption (HZ-5) compared to control coating. Post water immersion, fire test showed 7% increase in substrate temperature which is 18% less than control coating after water immersion fire test.
Abstract
Zirconium phosphate (ZrP) recently introduced in intumescent fire protective coating has shown improvement in developing ceramic layer. The tubular halloysite clay (THC) [...]
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Algoritmo de detección de fallas de sensado en convertidores CA/CC para micro-redes basado en análisis de componentes principales
S. Guamantica, L. Ortiz, A. Téllez, M. Ruiz Maldonado, S. Chamorro

Rev. int. métodos numér. cálc. diseño ing. (2022). Vol. 38, (4), 36

Abstract
Esta investigación propone un método para la Detección de Fallas en sensores relacionados con el Control Local de Convertidores de Fuente de Voltaje conectados a Microrredes AC/DC usando Análisis de Componentes Principales. Para lograr lo anterior, se realizan simulaciones sobre una Microrred de referencia compuesta por una variedad de cargas (lineales y no lineales), Generación Distribuida (convencional y renovable), así como Sistemas de Almacenamiento de Energía en Baterías DC y AC con sus respectivos convertidores. Los investigadores proponen dos escenarios de falla y un escenario de operación normal para este estudio. El escenario de operación normal, denominado en este documento como clase uno, sirve de referencia para realizar el análisis del comportamiento del método propuesto y su validación con respecto a los otros dos escenarios. Como resultado se obtuvo un algoritmo basado en Análisis de Componentes Principales que, a partir de los componentes principales de los casos o clases, calcula las diferencias entre los espacios obtenidos a partir de un total de 257 variables recolectadas en todas las barras del sistema y del sensado para Control Local.
Abstract
Esta investigación propone un método para la Detección de Fallas en sensores relacionados con el Control Local de Convertidores de Fuente de Voltaje conectados [...]
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Manufacturing of long recycled carbon fibre composites by injection
A. Fernández, M. Santangelo-Muro, J. Molina-Aldareguia, C. Lopes

Materiales Compuestos (2022). Vol. 03 - Comunicaciones Matcomp17 (2019), (Núm. 4 - País invitado: Colombia. Materiales Multifuncionales. Reciclaje y Sostenibilidad), 55

Abstract
Due to the rapid growth in the use of composite materials, environmental concerns have become an increasingly influential topic, making recyclability of composite materials a key issue. Furthermore, several related European laws have been passed to minimize the environmental impact of composites (EU 2000/53/CE [1], 2000/76/EC [2], 2004/35/EC [3]). Caused by the high energetic requirements and the huge amount of composite materials used in the manufacturing process, recycling supposes a reduction of a 70% in the costs and 98% in the energy demanded [4]. Once the fibers are obtained through pyrolysis, with a high retention of mechanical properties, the next step is the manufacturing process by injection using a thermoplastic polymeric matrix of polypropylene, a polymer widely used in the composite industry. For that purpose, a study of the compatibility of the fiber with the maleic anhydride polypropylene at different relations -10, 20 and 30%- has been carried out. In order to enhance the mechanical properties, a combination of homopolymer polypropylene, maleic anhydride polypropylene and recycled carbon fibers is studied through the production of a masterbach composed of maleic anhydride polypropylene and carbon fibers, followed by the addition of the homopolymer polypropylene. Once the pellets are obtained, they are injected. The samples injected are analyzed in terms of fiber distribution by scanning electron microscopy and tomography, thus the mechanical properties are evaluated through tensile, impact and bending tests, to determine the optimum fiber/resin ratio.
Abstract
Due to the rapid growth in the use of composite materials, environmental concerns have become an increasingly influential topic, making recyclability of composite materials [...]
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Sustainable composites based on carbon fiber recycled for the automotive sector
K. Gondra, A. Allue, J. Alonso

Materiales Compuestos (2022). Vol. 03 - Comunicaciones Matcomp17 (2019), (Núm. 4 - País invitado: Colombia. Materiales Multifuncionales. Reciclaje y Sostenibilidad), 56

Abstract
In the automotive sector, lightening weight is a key issue in the designing of vehicle components, to reach the CO2 emission limits that have been defined in Europe for the year 2020. That is why the strategy in the sector is to use fiber-reinforced composites, that allow to lighten the metal structures between 15 and 40% depending on the type of fiber. On the other hand, the recyclability is another important point, since the directives on the end of the useful life of the vehicles, stipulates that will be obligatory the recycling of 85% of the vehicle, not contemplating the "recovery of energy" of polymers as a means for its recycling. Composites, although they are lightweight and have a high resistance, have the disadvantage of their recyclability, and the reality is that environmental legislation is becoming increasingly restrictive, and it is urgent to find solutions to landfill. This is one of the reasons why the pyrolysis of carbon composites for the recovery of carbon fiber, and its reuse in the form of non-woven MAT, and the thermostable resins that can be recycled and reprocessed, can lead to a new generation of sustainable and recyclable composites in the automotive sector.
Abstract
In the automotive sector, lightening weight is a key issue in the designing of vehicle components, to reach the CO2 emission limits that have been defined in Europe for the [...]
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Bibliography - Big Data Analytics
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Entrepreneurship for Digital Economy (2022). Vol. Chapter 4 - Big Data Analytics, 35
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Conclusion - Big Data Analytics
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Entrepreneurship for Digital Economy (2022). Vol. Chapter 4 - Big Data Analytics, 34
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Digital Economy after COVID-19
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Entrepreneurship for Digital Economy (2022). Vol. Chapter 4 - Big Data Analytics, 32
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Online consumer behavior
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Entrepreneurship for Digital Economy (2022). Vol. Chapter 4 - Big Data Analytics, 31
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Millennials and other generations face the Digital Economy
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Entrepreneurship for Digital Economy (2022). Vol. Chapter 4 - Big Data Analytics, 30
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Digital Divide
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Entrepreneurship for Digital Economy (2022). Vol. Chapter 4 - Big Data Analytics, 29
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Introduction to Big Data Analytics
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Entrepreneurship for Digital Economy (2022). Vol. Chapter 4 - Big Data Analytics, 28
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Bibliography - Digital technologies
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Entrepreneurship for Digital Economy (2022). Vol. Chapter 3 - Digital technologies, 27
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Conclusion - Digital technologies
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Entrepreneurship for Digital Economy (2022). Vol. Chapter 3 - Digital technologies, 26
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Case Study - Digital technologies
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Entrepreneurship for Digital Economy (2022). Vol. Chapter 3 - Digital technologies, 25
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Digital Reality
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Entrepreneurship for Digital Economy (2022). Vol. Chapter 3 - Digital technologies, 24
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Cloud, 5G and Edge Computing
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Entrepreneurship for Digital Economy (2022). Vol. Chapter 3 - Digital technologies, 23
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Internet of Things
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Entrepreneurship for Digital Economy (2022). Vol. Chapter 3 - Digital technologies, 22
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Introduction to digital technologies
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Entrepreneurship for Digital Economy (2022). Vol. Chapter 3 - Digital technologies, 21
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Bibliography - Artificial Intelligence & Blockchain
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Entrepreneurship for Digital Economy (2022). Vol. Chapter 2 – Artificial Intelligence & Blockchain, 20
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Conclusion - Artificial Intelligence & Blockchain
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Entrepreneurship for Digital Economy (2022). Vol. Chapter 2 – Artificial Intelligence & Blockchain, 19
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The blockchain
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Entrepreneurship for Digital Economy (2022). Vol. Chapter 2 – Artificial Intelligence & Blockchain, 18
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Artificial Intelligence and its Decline
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Entrepreneurship for Digital Economy (2022). Vol. Chapter 2 – Artificial Intelligence & Blockchain, 17
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Big Data
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Entrepreneurship for Digital Economy (2022). Vol. Chapter 2 – Artificial Intelligence & Blockchain, 16
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Artificial intelligence
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Entrepreneurship for Digital Economy (2022). Vol. Chapter 2 – Artificial Intelligence & Blockchain, 15
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Pre-test Digital Economy
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Entrepreneurship for Digital Economy (2022). Vol. Chapter 2 – Artificial Intelligence & Blockchain, 14
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Introduction to Artificial Intelligence & Blockchain
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Entrepreneurship for Digital Economy (2022). Vol. Chapter 2 – Artificial Intelligence & Blockchain, 13

Abstract
Introduction to Artificial Intelligence & Blockchain
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Damage detection in a fiber reinforced polymers based tower of a floating offshore wind and tidal power platform using structural dynamic parameters
P. Sierra, X. Martinez, R. Chacon, F. Otero, F. Turon

Materiales Compuestos (2022). Vol. 07 - COMUNICACIONES MATCOMP21 (2022), (Núm. 2 - Aplicaciones Industriales - Caracterización), 170

Abstract
The development of offshore renewable energy structures is growing at a fast pace, and their maintenance will become critical in further years. Because steel corrosion on offshore structures is one of their highest maintenance cost, researchers are working to replace steel by Fibre Reinforced Polymers (FRP), due to their immunity to corrosion. This is done in the EU H2020 funded project FIBREGY, which also seeks improving maintenance costs by incorporating Structural Health Monitoring (SHM) strategies. A critical issue in SHM is the damage detection process, which is addressed in this paper. This study aims to characterize the dynamic behaviour of an offshore windmill FRP tower, and its evolution due the presence of structural damage. This analysis will be carried out using a Finite Element Model (FEM) of the structure, and the Serial-Parallel mixing theory to characterize the material performance. A sensitivity analysis of the changes in the dynamic response of the tower (frequencies and modal shapes) produced by structural damage is carried out. This analysis will provide the optimum design variables and objective functions required by a damage detection algorithm. The algorithm is optimization based, since it converts the damage detection problem into a mathematical one, and finds the best design variables to minimize the objective function. The algorithm is also model based, as it uses the structural model to obtain the objective function for the proposed design variables. Finally, this work presents the analysis of a potential damage scenario, in order to evaluate if the damage is effectively detected.
Abstract
The development of offshore renewable energy structures is growing at a fast pace, and their maintenance will become critical in further years. Because steel corrosion on [...]
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Study of the influence of using recycled brass fibres from electrical discharge machining process on the physical, thermal and mechanical properties of the resulting mortar
R. Borinaga, A. Orbe, J. Canales, S. Plaza

Materiales Compuestos (2022). Vol. 03 - Comunicaciones Matcomp17 (2019), (Núm. 4 - País invitado: Colombia. Materiales Multifuncionales. Reciclaje y Sostenibilidad), 53

Abstract
Nowadays, metallic fibre reinforced cementitious composites are widely used on many different construction elements: concrete beds, slabs, precast concrete industry, etc. Fibres reduce the crack generation due to the cementitious composite shrinkage and improves its flexural strength, toughness and durability. If metallic waste materials from the industrial manufacturing sector were used instead of using the commercially available metallic fibres, the energy of both the waste recycling process and the manufacturing of the actual commercial metallic fibres would be saved. This paper studies the use of the waste residual brass fibres generated during the electrical discharge machining process as a reinforcement on mortars. With that in mind, two different fibre types (brass covered steel and recycled brass) on two different mix proportions (0.65% and 1.3% by unit volume of mortar) were added to a self-leveling non-reinforced mortar taken as a reference to evaluate their influence on the physical, thermal and mechanical properties of the resulting mortar. According to the results, for both types of fibres studied, the higher the fibre proportion used, the higher were the density, the thermal conductivity, the flexural strength and the compressive strength.of the resulting mortars. Recycled brass fibres increased the thermal conductivity and decreased the volumetric heat capacity of the resulting mortars more than the steel fibres, which is interesting, for example, on self-levelling mortars used on radiant floor heat exchangers. However, less increase was observed on the mechanical properties of the recycled brass fibre reinforced mortars than that of the steel fibre reinforced mortars, due to the shorter length of the former fibres (5-10 mm for the recycled brass fibres, 13 mm for the steel fibres). Therefore, the parameter that controls the cutting frequency of the waste wire of the electrical discharge machine should be modified to adapt the final fibre length to that of the commercially available fibres.
Abstract
Nowadays, metallic fibre reinforced cementitious composites are widely used on many different construction elements: concrete beds, slabs, precast concrete industry, etc. [...]
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Compressive behavior of a natural core
E. Gómez-Meisel, S. Sánchez-Saez, E. Barbero

Materiales Compuestos (2022). Vol. 03 - Comunicaciones Matcomp17 (2019), (Núm. 4 - País invitado: Colombia. Materiales Multifuncionales. Reciclaje y Sostenibilidad), 52

Abstract
Composite sandwich structures with core cellular materials are widely used in diverse industries such as the aerospace, marine, car, and wind industries due to their good mechanical properties on bending. The growing environmental awareness has increased the interest in the use of materials from biodegradable and renewable sources. During recent years, there has been an increasingly growing interest in the use of agglomerated cork as a core material in sandwich structures, replacing synthetic polymeric foams in specific applications. Among its remarkable combination of properties, we can find a hyperelastic behaviour, low thermal conductivity, low permeability, and good energy absorption and vibration damping properties. Additionally agglomerated cork is produced from the waste of the cork industry, being a renewable and biodegradable material that is environmentally sustainable. The aim of this work is to address the quasi-static and dynamic compression testing of two types of agglomerated cork of different densities, using a servo-hydraulic testing machine and drop weight tower. The mechanical behaviour and energy absorption properties at different strain rates are evaluated from the contact force measurements and estimations of impact kinetic energy. Additionally, Digital Image Correlation (DIC) is used to estimate the variability in the local strain through the test specimen.
Abstract
Composite sandwich structures with core cellular materials are widely used in diverse industries such as the aerospace, marine, car, and wind industries due to their good [...]
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Characterization of light mortars with alkali activated SiMn slag and recycled expanded polystyrene
H. Hafez, V. Ferrándiz, E. Alcocel, . R.Navarro, I. Sánchez, E. Zornoza

Materiales Compuestos (2022). Vol. 03 - Comunicaciones Matcomp17 (2019), (Núm. 4 - País invitado: Colombia. Materiales Multifuncionales. Reciclaje y Sostenibilidad), 51

Abstract
One of the main challenges of binder manufacturing industry is the reduction of its environmental impact. In this context, the key is the obtention of materials whose fabrication uses lower amount of natural resources and energy consumption. One of the the main strategies to achieve that goal is the incorporation of alkali activation processes to waste material or by-products. In this work, a SiMn slag has been alkali activated to prepare light mortars in which partial substitution of the aggregates by expanded polystyrene has been applied. An aggregate replacement up to 45% by volume has been used. In addition, also the SiMn has been used as aggregate in order to explore its valorization through that application. The following properties have been evaluated: fresh mortar workability, compressive strength, drying and autogenous shrinkage, water absorption by capillarity, apparent density and thermal conductivity. The intended application for this type of material would be as light cladding with improved isolation properties. Results have shown that the replacement up to 45% of natural aggregate by expanded polystyrene produces a decrease of the compressive strength up to 70%, a reduction of the density of 32%, an increase of the water absorption of 75% and a decrease of the thermal conductivity up to 87%.
Abstract
One of the main challenges of binder manufacturing industry is the reduction of its environmental impact. In this context, the key is the obtention of materials whose fabrication [...]
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Improvement in the resistance against moisture presence in plasters and self-levelling screeds based of natural anhydrite waste
C. Polo, E. Zornoza, P. Garcés, E. Alcocel

Materiales Compuestos (2022). Vol. 03 - Comunicaciones Matcomp17 (2019), (Núm. 4 - País invitado: Colombia. Materiales Multifuncionales. Reciclaje y Sostenibilidad), 50

Abstract
The anhydrite is a natural compound that co-exists alongside with the gypsum rock in some geological formations. Formulating new products for plasters and self-levelling screeds is the most common way to treat and recover the anhydrite waste in Europe. In this case, we´ll re-use natural anhydrite waste originated in a gypsum quarry located in the province of Alicante (Spain), having in mind this could be extrapolated to any other gypsum quarries. The compound is chemically composed of anhydrous calcium sulfate that could be activated through catalysts, hydrating and turning itself into dehydrate calcium sulphate (gypsum). The aforementioned material presents great aptitudes for self-levelling screeds due to its good reology and little shrinkage. Generally, they are used in building industry once the building envelope is finished and water tight as its water solubility restricts its use in damp environments. The current paper presents improvements in the resistance against water presence by dosing damp-proof product as siloxan derivatives and zinc stearate. There have been obtained important improvements in the reduction of superficial absorption and capilarity absortion. Also the effect of these aditives on the mechanical properties of the self-levelling compound have been studied in this paper.
Abstract
The anhydrite is a natural compound that co-exists alongside with the gypsum rock in some geological formations. Formulating new products for plasters and self-levelling screeds [...]
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Additive Manufacturing, an opportunity for Composite recycling
G. López, J. Vázquez, F. Móstoles, E. Fernández, T. Varela, J. Gómez

Materiales Compuestos (2022). Vol. 03 - Comunicaciones Matcomp17 (2019), (Núm. 4 - País invitado: Colombia. Materiales Multifuncionales. Reciclaje y Sostenibilidad), 49

Abstract
Composite materials are one of the fundamental pillars of the aerospace industry due to their high strength and specific stiffness. However, their use involves large amounts of waste that require difficult and expensive treatments for its disposal. The objective of this analysis is to present the additive manufacturing by means of deposition of molten filament as a process capable of giving a second life to the waste of both the composite materials and the auxiliary materials used during its manufacturing process. The printing filaments are developed from a PA 6,6 matrix obtained from vacuum bags used for the manufacture of pre-impregnated composites and by means of a reinforcement of short carbon fiber obtained from the residues of pieces of composite material or uncured fibre. The printing trials as well as the specimens for tests and demonstrators have been produced in an open printing system allowing to obtain the optimal process parameters for this type of materials. The application of these materials and technologies within the aerospace field in flying parts as well as in production jigs and tools as well as in other industries such as automotive, sporting goods or accessories constitutes a key element to align the use of composite materials with the objectives of eco-efficiency that society demands for the immediate future.
Abstract
Composite materials are one of the fundamental pillars of the aerospace industry due to their high strength and specific stiffness. However, their use involves large amounts [...]
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Development of new filaments for 3D printing based on bio-inspired ceramics
J. Rojas-Lozano, P. Diaz-Rodriguez, P. Barreiro, E. López-Senra, C. Rodríguez-Valencia, M. López-Álvarez, M. Landin, P. González, J. Serra

Materiales Compuestos (2022). Vol. 03 - Comunicaciones Matcomp17 (2019), (Núm. 4 - País invitado: Colombia. Materiales Multifuncionales. Reciclaje y Sostenibilidad), 48

Abstract
3D printing allows the development of devices in a wide range of sectors, including the automotive industry, construction, aeronautics, food, textiles and also biomedical, among others. There are several technologies being the impression by molten deposition (FDM) one of the most widespread. In the particular case of biomedical engineering, three are the main application and research axes: (1) biomodels for the preparation of surgical interventions, (2) design and manufacture of customized biomedical devices and (3) porous scaffolds for regenerative medicine. The objective of the present study focuses on the development of a new filament for 3D-FDM printing composed of polylactic acid (PLA) and a biphasic crystalline bioceramic of marine origin (Biofast). Several filament formulations were obtained after extrusion of mixtures with variable proportions PLA / Biofast. The physical-chemical properties of both the filament and the printed pieces were studied by scanning electron microscopy, Raman and IR spectroscopy. The analyzes show that the bioceramic particles are evenly distributed in the polymer matrix and their incorporation can be controlled depending on the selected mixture. As for the crystal structure and links, manufacturing processes do not originate modifications that may affect the biocompatibility of the final device. Thus, these new filaments are shown as potential candidates for application in biomedical engineering.
Abstract
3D printing allows the development of devices in a wide range of sectors, including the automotive industry, construction, aeronautics, food, textiles and also biomedical, [...]
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Polyamide/sepiolite Nanocomposites for application in Additive Manufacturing processPolyamide/sepiolite Nanocomposites for application in Additive Manufacturing process
. M.Herrero, K. Núñez, E. Cañíbano, .. Merino, J. Pastor

Materiales Compuestos (2022). Vol. 03 - Comunicaciones Matcomp17 (2019), (Núm. 4 - País invitado: Colombia. Materiales Multifuncionales. Reciclaje y Sostenibilidad), 47

Abstract
Additive manufacturing includes a series of technologies where a three-dimensional object is fabricated by the superposition of different layers of material. From all this technologies, fused filament fabrication (FFF) may the most mature approach. This technology has been used mainly for rapid prototyping, but it starts to be implemented at the industrial level due to the low energy consumption and greater efficiency in the use of raw materials. Currently, the most used polymers in FFF process are the polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS). However, their mechanical properties and service temperature are not good enough to be used in applications where high technical demands are recquired. Due to these shortcomings, scientists have focused on other technical polymers such polyether ether ketone (PEEK) and polyetherimide (PEI). Other approach to improve mechanical performance of traditional materials is the use of fibers or nanofibers, which allows printed parts with new functionalities and/or improved properties. In this study a needle-like nanoclay has been used for obtaining bio-polyamide nanocomposites, specially prepared for FFF application. The final printed parts showed good dimensional stability and good mechanical properties, which place them between the conventional (PLA and ABS) and the technical materials (PEEK and PEI).
Abstract
Additive manufacturing includes a series of technologies where a three-dimensional object is fabricated by the superposition of different layers of material. From all this [...]
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3D printed composites doped with CNTs with self-sensing capabilities
A. Cortés, X. Sánchez-Romate, A. Jiménez-Suárez, M. Campo, S. Prolongo, . A.Ureña

Materiales Compuestos (2022). Vol. 03 - Comunicaciones Matcomp17 (2019), (Núm. 4 - País invitado: Colombia. Materiales Multifuncionales. Reciclaje y Sostenibilidad), 54

Abstract
In the last years, 3D printing is attracting the interest from the industry and scientific community because of the reduction of manufacturing times and machining processes. Furthermore, it is important to develop materials with new functionalities or enhanced properties regarding the currently available materials In this context, the addition of nanoparticles, such as carbon nanotubes (CNTs), is arousing much interest. More specifically, CNTs have a vast potential in Structural Health Monitoring (SHM) applications, due to their piezoresistive behaviour and tunnelling conduction mechanisms providing a great electrical sensitivity under strain. The present study aims to exploit those CNT capabilities for SHM purposes, combining them with the 3D printing manufacturing technology. To achieve this, Digital Light Processing (DLP) 3D printing technique has been used to obtain composite materials based on a commercial resin doped with CNTs, by varying the nanoparticles content. First results obtained for tensile and flexural tests show an electrical sensitivity slightly higher to the typical values of metallic gauges, thus, proving a high potential for strain monitoring applications.
Abstract
In the last years, 3D printing is attracting the interest from the industry and scientific community because of the reduction of manufacturing times and machining processes. [...]
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Additive manufacturig of semiconductive nanocomposites throguh stereolithography
A. León, S. Molina

Materiales Compuestos (2022). Vol. 03 - Comunicaciones Matcomp17 (2019), (Núm. 4 - País invitado: Colombia. Materiales Multifuncionales. Reciclaje y Sostenibilidad), 46

Abstract
In the current work we present a series of nanocomposite materials printed via stereolithography using an acrylic organic matrix together with graphite nanoplatelets (GNP) as inorganic filler. It was generally observed that presence of GNP decreases the mechanical properties with respect to the unmodified resin, probably because the presence of pores around GNP. However, composites containing 2.5 wt% GNP showed electrical resistivity values in the range of 106 Ohm·cm, nine orders of magnitude below unmodified resin. In these conditions we state we have a material with characteristic semiconductive properties.
Abstract
In the current work we present a series of nanocomposite materials printed via stereolithography using an acrylic organic matrix together with graphite nanoplatelets (GNP) [...]
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Multilayered, bio-based polymer/clay aerogel composites
M. Sánchez-Soto, ,. Cruz, . P.Joniken, T. Abt, J. Cailloux, M. Maspoch, O. Santana

Materiales Compuestos (2022). Vol. 03 - Comunicaciones Matcomp17 (2019), (Núm. 4 - País invitado: Colombia. Materiales Multifuncionales. Reciclaje y Sostenibilidad), 45

Abstract
Low flammable foam-like materials based on renewable bio-based polymers and sodium montmorillonite clay (MMT) were created using water as a solvent and following a simple freeze-drying process. Composites were formed by adding layers of the previously created gel precursors to a Polyvinyl alcohol / MMT based aerogel. A multi-step and a one-pot processes were followed to make the multi-layered aerogels, and the resultant properties of the different processing systems were compared. Similar adhesion between layers was observed in both processes although the multi-step required a longer manufacturing time. With the aim of improving the mechanical properties, chemical crosslinking of the Polyvinyl alcohol base was induced prior to lyophilization by immersing the material in a sodium borate solution. It was found that the mechanical response under compression was enhanced in regards to the non-crosslinked systems. A highly retardant composite material was fabricated by superposing an alginate/MMT at the external layer as the most promising system for fire protection
Abstract
Low flammable foam-like materials based on renewable bio-based polymers and sodium montmorillonite clay (MMT) were created using water as a solvent and following a simple [...]
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Development of new multifunctional coatings: transparent, with superhydrophobicity properties and wear resistance
N. Mas, A. Yedra, C. Manteca, M. González-Barriuso, L. Soriano, L. Pérez-Gandarillas

Materiales Compuestos (2022). Vol. 03 - Comunicaciones Matcomp17 (2019), (Núm. 4 - País invitado: Colombia. Materiales Multifuncionales. Reciclaje y Sostenibilidad), 44

Abstract
In the last decade, superhydrophobicity (SH) phenomenon has aroused a great interest. This fact has been motivated by large and important functionalities that can be achieved by these SH surfaces: self-cleaning solutions, water repellancy, anticorrosive, anti-stain, anti-icing, antifouling, among others. SH is defined by the low surface energy of the material as well as the morphology of the own surface. However, due to the fact that hydrophobicity is a superficial property, its main disadvantage is its limited wear resistance, which causes a low durability and a limited comercial use. This fact, together with the complexity and low effectiveness, from the economic point of view compared with the existing coatings fabrication techniques, makes necessary the research of new alternatives for the demanding market, being a technological challenge to find them. Moreover, organic coatings are widely used in industry in a number of surfaces due to the ease and low cost of application methods. Concretely, nanocomposites fabrication from organic polymers using nanoparticles as additives, has been creating high expectatives in the coatings industry sector. In this work, new organic coatings based on the integration of surface modified nanoparticles with hydrophobic moieties have been developed, in order to achieve hidrophobicity in organic polymeric matrices (paints). Likewise, different nanoparticles have been used in order to achieve synergistic effects that could provide a determined superficial rugosity and then, reaching simultaneously transparent, hydrophobic and abrasion wear resistant coatings.
Abstract
In the last decade, superhydrophobicity (SH) phenomenon has aroused a great interest. This fact has been motivated by large and important functionalities that can be achieved [...]
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Aliphatic Polyurethane Matrix for more sustainable UV-Resistant Composites
D. Mentizi, A. Hecking, S. Strauß, D. Achten, D. Guiteras

Materiales Compuestos (2022). Vol. 03 - Comunicaciones Matcomp17 (2019), (Núm. 4 - País invitado: Colombia. Materiales Multifuncionales. Reciclaje y Sostenibilidad), 43

Abstract
During the last years, composites based on renewable sources gained significant interest due to a globally increased awareness on sustainability. In order to address these challenges and to achieve ambitious sustainability targets, such as the reduction of greenhouse gas emissions, Covestro recently introduced composites from a new aliphatic and bio-based polyurethane, which bears a bio-content of ca. 70%. A combination of such bio-based polyurethanes with bio-based reinforcing fibers can lead for the first time to a composite with a bio-content of appr. 90%. Due to the aliphatic nature of the bio-based isocyanates, the resulting composites are characterized by an inherent UV- and weathering resistance, which makes them primarily suitable for outdoor applications and allows to omit additional protective coatings steps. A corresponding matrix material for pultruded composites, which is based on conventional raw materials, was launched under the brand name Desmocomp®.
Abstract
During the last years, composites based on renewable sources gained significant interest due to a globally increased awareness on sustainability. In order to address these [...]
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LIFE CYCLE ASSESSMENT OF LATTICE JOIST PRECAST SLABS WITH TIRE RUBBER RESIDUE ADDITION
D. Sampaio, A. Sanches, J. AKASAKI

Materiales Compuestos (2022). Vol. 07 - COMUNICACIONES MATCOMP21 (2022), (Núm. 1 - Sostenibilidad y reciclaje - Fabricación), 160

Abstract
The methodology that integrates the three sustainability pillars, from a life cycle perspective, is called Life Cycle Sustainability Assessment (LCSA). LCSA provides the highest level of assessment among the existing tools, as it allows a holistic understanding of the sustainability of products and processes, which translates into better support for decision-makers. In this work, LCSA was carried out considering the combined application of the Life Cycle Assessment (LCA), Life Cycle Costing (LCC) and Social Life Cycle Assessment (SLCA), to evaluate and compare the environmental, social and economic impacts of lattice joist precast slabs based on three scenarios: (I) conventional concrete, (II) slabs produced from concrete with the addition of tire rubber residue, (III) slabs produced from concrete with the addition of tire rubber residue and rice hulk ash (RHA). The SimaPro software and the Ecoinvent database were used to conduct the analyses, in addition to prices from local construction materials suppliers and official public data on Brazilian society. The Life Cycle Impact Assessment methods used were ReCiPe 2016 Midpoint Hierarquist v.1.01, in the environmental pillar; material acquisition, transportation and energy costs in the economic pillar; Reference Scale Approach focused on the category Workers in the social pillar. It was possible to conclude that Scenario I was the most adequate alternative, even though it did not have alternative materials in its composition. The replacement of tire rubber waste by sand in Scenarios II and III proved to be disadvantageous from the point of view of sustainability, even with the slight improvement by also replacing part of the cement with RHA in Scenario III.
Abstract
The methodology that integrates the three sustainability pillars, from a life cycle perspective, is called Life Cycle Sustainability Assessment [...]
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Graphene for Anti-icing
Z. Martin, T. Blanco, A. Butragueno, J. Sánchez, . P.Vázquez, A. Scidà, V. Palermo, E. Treossi, F. Valorosi

Materiales Compuestos (2022). Vol. 03 - Comunicaciones Matcomp17 (2019), (Núm. 4 - País invitado: Colombia. Materiales Multifuncionales. Reciclaje y Sostenibilidad), 42

Abstract
Aeronautical sector, like many others, is trying to benefit from exceptional properties of graphene as soon as possible (low density, unique electrical, thermal, optical, mechanical properties…). In fact composite airframe enhancement by graphene related materials is part of the biggest European research project, the Graphene Flagship, which is trying to bring graphene from lab to society. Then, within this context, a first high potential application of graphene in aeronautical composite structure has been selected by Airbus: de- / anti-icing system. The graphene concept studied for anti-icing application is an electro-thermal system, where heat is generated by applying electrical voltage by Joule effect. Key work performed in this study was focused on following aspects: identification of use cases and requirements, selection of graphene based related material, integration concepts within carbon fiber reinforced polymers (CFRP), demonstration or proof of concept through manufacturing and functionality tests, and, finally, preliminary value and risk assessment of solution. As per work performed, it can be concluded that the potential of proposed innovative graphene based electro-thermal system for composite aeronautical part anti-icing function has been preliminary proven and demonstrated. However, there is still a long way to increase the maturity, scale-up the concept, demonstrate cost saving and benefits versus other solutions, as well as to overcome the identified risks.
Abstract
Aeronautical sector, like many others, is trying to benefit from exceptional properties of graphene as soon as possible (low density, unique electrical, thermal, optical, [...]
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ECOFUNEL: New Ad-hoc injection molding composites with enhanced electrical features for airborne systems
S. Juan, V. Ventosinos, T. Fournier, E. Robert

Materiales Compuestos (2022). Vol. 03 - Comunicaciones Matcomp17 (2019), (Núm. 4 - País invitado: Colombia. Materiales Multifuncionales. Reciclaje y Sostenibilidad), 41

Abstract
The European Commission has a strong compromise in matter of developing eco-friendly designs for airborne systems to reduce both manufacturing and in-service contamination related to those elements. One of the main approaches in this sense is to substitute metal parts by stiff, light-weight, multifunctional and recyclable polymer-based compounds which allow eliminating hazardous surface treatments and also permit reusing the materials at the end of life of the components. In this framework, ECOFUNEL project was launched by Liebherr Aerospace SAS with the consortium formed by FIDAMC, CTAG and CANOE, and with the financial support of the European Commission under the Clean Sky 2 initiative. The work aims to giving alternatives to current metal valve bodies of air conditioning systems for aircraft, by investigating the use of thermoplastic while addressing the challenge of keeping sufficient electrical conductivity and mechanical properties of the part. The research line put the focus on the development of new functionalized material formulations based on high performance injection molding thermoplastic compounds with enhanced electrical feature. New formulations are designed, produced and studied systematically within ECOFUNEL and a final prototype element will be created employing the ad-hoc own-designed materials.
Abstract
The European Commission has a strong compromise in matter of developing eco-friendly designs for airborne systems to reduce both manufacturing and in-service contamination [...]
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Optimization of mechanical properties by the impregnation velocity control in infusion processes
J. Almazán*, E. López, F. Díaz

Materiales Compuestos (2022). Vol. 07 - COMUNICACIONES MATCOMP21 (2022), (Núm. 1 - Sostenibilidad y reciclaje - Fabricación), 167

Abstract
Reducing defects in manufacturing processes is one of the greatest challenges in the composites industry. This reduction mean an increment in the mechanical properties, repeatability and optimized structural weight. It is known the relationship between the impregnation velocity and the amount of defects, especially air entrapment in liquid impregnation processes. Its consequences are highlighted in the resin infusion process, where the flow velocity is not constant throughout the process. Such heterogeneity leads to non-homogeneous mechanical properties in the material. This work is base on the development of a methodology to control the impregnation process. It has demonstrated a substantial improvement in the mechanical properties when the flow velocity is controlled and kept around the optimum value.The methodology aims to identify the optimum impregnation velocity value through experimentation, and then, this value is applied during during the whole infusion process. For this purpose, an artificial vision system has been used, which allows keeping the flow velocity constant and near to the optimum value which optimize the mechanical properties. Its experimental application in both conventional and stitched laminates has shown an increase in the tensile and impact mechanical properties. At the same time, level of control of the infusion process has been enhanced.
Abstract
Reducing defects in manufacturing processes is one of the greatest challenges in the composites industry. This reduction mean an increment in the mechanical properties, repeatability [...]
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Thermal Protection System Based on Reinforced Polymers with Carbon Nanotubes and Titanium Dioxide for Industrial Aplications
A. Isaza, S. Patiño, E. Arango, A. Tamayo, N. Rave

Materiales Compuestos (2022). Vol. 03 - Comunicaciones Matcomp17 (2019), (Núm. 4 - País invitado: Colombia. Materiales Multifuncionales. Reciclaje y Sostenibilidad), 40

Abstract
In this research, a composite material based on thermostable polymers, reinforced with nano and micro structures was developed and thermally characterized. The polymer used was the epoxy, the microstructures, Titanium dioxide TiO2 and the nanostructures, the multiwalled carbon nanotubes, those, were integrated into the matrix by the method of ultrasonication in two stages, a first in which they were dispersed in a time of 5 minutes, using a sonicator with energy of 750 Watts, frequency of 20 kHz, 1:1 pulser and 40% amplitude, using as solvent, styrene monomer for a posterior inclusion of the solution obtained in the matrix, corresponding to the second stage, where the previous specifications were followed, for a time of 1 minute. Configurational designs for the thermal protection system were established and characterized under international standard ASTM E 285-80, observing their effect on the form, mechanisms and speed of thermal degradation; and it was reported in terms of thermal gradient. A thermal efficiency of 24% was obtained in the nanocomposite, and an improvement of around 15% compared to non- nanoreinforced polymers.
Abstract
In this research, a composite material based on thermostable polymers, reinforced with nano and micro structures was developed and thermally characterized. The polymer used [...]
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Study of the influece of flame retardant additives on ultra-violet curing thermosetting composites
N. Eulate, F. Vallejo, G. Goenaga, M. Urrutxua, J. Ballestero, P. Ares, A. Allue, J. Gómez

Materiales Compuestos (2022). Vol. 07 - COMUNICACIONES MATCOMP21 (2022), (Núm. 2 - Aplicaciones Industriales - Caracterización), 179

Abstract
Fibre-reinforced polymer composites are materials capable of reducing weight while maintaining optimised properties in multiple applications. However, the use of composite materials is not suitable for all sectors, where the need for improved fire properties is highlighted. In the present study, a thermosetting matrix composed of UV-curable acrylic monomers and UV-transparent aluminium trihydrate (ATH) flame retardant fillers have been added to UV-transparent polyester resin for the manufacture of flame retardant composites. An in-depth study of the most suitable types of ATH-based flame retardant additives and possible synergistic combinations to improve the fire performance of the UV-curable composite has been carried out. Not only has the type of flame retardant been studied, but also the most suitable additive percentage to comply with railway sector regulations. The compatibility between the fillers and the matrix has been analysed by means of dielectric analysis, as well as the properties of the matrix and final composites against fire and mechanical properties.
Abstract
Fibre-reinforced polymer composites are materials capable of reducing weight while maintaining optimised properties in multiple applications. However, the use of composite [...]
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Use of rapid prototype for desing and cosntruction of composites materials bioreference’s parts used in photovoltaic applications
M. López, M. Tousb

Materiales Compuestos (2022). Vol. 03 - Comunicaciones Matcomp17 (2019), (Núm. 4 - País invitado: Colombia. Materiales Multifuncionales. Reciclaje y Sostenibilidad), 39

Abstract
It is showed a methodology to create models and molds on fiberglass reinforced polyester resin using geometries drawers in graphics design software and impressions in real-scale models using 3D printers. The real application of this exercise is the construction of a structure for photovoltaic panels for solar energy solutions. This methodology allows to optimize manufacturing times with complex geometries. This is innovative in the local industry in Latin America due to the topological optimization obeying a morphological refinement based on natural structures, as well as the palm-bottle design, that is an emblematic tree of the Andean region.
Abstract
It is showed a methodology to create models and molds on fiberglass reinforced polyester resin using geometries drawers in graphics design software and impressions in real-scale [...]
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Pseudo-ductility under tensile and compressive loading in ±45º laminates
M. Serna Moreno, S. Horta Muñoz

Materiales Compuestos (2022). Vol. 07 - COMUNICACIONES MATCOMP21 (2022), (Núm. 2 - Aplicaciones Industriales - Caracterización), 176

Abstract
This work focuses on analyzing the uniaxial response of carbon fiber reinforced polymer matrix laminates with the configurations [±45]2S under tension and [±45]4S under compression. These present non-linear stress-strain evolutions that allow them to withstand large deformations before losing their load-carrying capacity. Both responses are characterized by a first linear stage, followed by a plateau in which the strain grows without increasing the stress level, and finally by a re-stiffening phase. But there are quantitative differences that lead to different failure patterns, which are explained with the help of the state of stress in the plane of maximum shear stress. For a better understanding of the process, tensile load-unload-reload tests are performed to verify if the energy recovered in each cycle could be related to the loss of the apparent stiffness. During the first two stages of the mechanical response, the laminate suffers a progressive damage with a reduction in stiffness related to the dissipated energy, but this pattern is not repeated in the last stage of strain hardening. Based on the experience of other authors, it is assumed that the re-stiffening stage follows a different pattern due to possible microstructural changes in the matrix during the plateau. These are promoted by a narrowing process under tensile loads and a local widening of the test zone under compression. The dimensional changes perpendicular to the load direction are observed thanks to the strain fields obtained by Digital Image Correlation.
Abstract
This work focuses on analyzing the uniaxial response of carbon fiber reinforced polymer matrix laminates with the configurations [±45]2S under tension and [±45]4S [...]
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SELF-HEALING STRATEGIES IN RUBBER COMPOSITES
S. Utrera-Barrios, J. Araujo-Morera, R. Manzanares, R. Verdejo, M. López-Manchado, M. Hernandez Santana

Materiales Compuestos (2022). Vol. 07 - COMUNICACIONES MATCOMP21 (2022), (Núm. 1 - Sostenibilidad y reciclaje - Fabricación), 107

Abstract
Inspired by some of the mechanisms that occur in nature, self-healing materials are characterized by the ability to recover, partially or totally, their initial properties after suffering damage. These materials constitute an efficient alternative for extending the lifecycle of products, as well as for reducing the amount of waste generated. At the same time, they reduce maintenance and repair costs. In this work, examples of recent developments in the field of elastomeric composite materials are presented, studying different matrices, natural rubber (NR), epoxidized natural rubber (ENR), styrene-butadiene rubber (SBR) and nitrile rubber (NBR), and using diverse repair strategies, hydrogen bonds, disulfide exchange reactions, Diels-Alder chemistry and ionic interactions. The effect of adding carbon-derived reinforcing fillers (graphene oxide) and sustainable alternative fillers (ground tire rubber) is also analyzed. It is studied how the presence and type of filler influences the healing capacity of elastomeric matrices, reaching repair efficiencies of up to ~80%, without detriment to their mechanical performance.
Abstract
Inspired by some of the mechanisms that occur in nature, self-healing materials are characterized by the ability to recover, partially or totally, their initial properties [...]
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Experimental validation of a novel anti-buckling device for compression after impact tests
F. Simón Fuentes, M. Jiménez, P. Luna, K. Muñoz, R. Ocaña, L. Vicente, J. Toral, R. Olmo

Materiales Compuestos (2022). Vol. 07 - COMUNICACIONES MATCOMP21 (2022), (Núm. 2 - Aplicaciones Industriales - Caracterización), 175

Abstract
Compression After Impact (CAI) test is normally used for the assessment of damage tolerance of composite laminates. The applicable specification for the execution of these tests is AITM 1-0010. However, for thicknessess under 4mm were buckling occurs, the applicable specification is the AITM 1-0077, which introduces the use of anti-buckling tooling covering the entire surface of the specimens. The tooling, which is used in the aeronautical industry for the testing of thin specimens presents two problems which are the difficulty of assembly and of obtaining realiable results, and the visibility of the specimen during the test. This work comprises the design, manufacturing and validation of a novel anti-buckling device for compression after impact thin specimens. For that purpose, a study of the specification toolings along with a review of the already developed anti-buckling tooling literature has been carried. As part of the validation process three series of impacted specimens of 3mm thickness. This activity is developed as part of the project CERES, which is framed under Clean Sky 2, and has the main objective of validating the manufactured anti-buckling tooling. This tooling has been developed as an innovative solution for its application in compression after impact thin specimens.
Abstract
Compression After Impact (CAI) test is normally used for the assessment of damage tolerance of composite laminates. The applicable specification for the execution of these [...]
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Two-plane bending test applied to unidirectional composite laminates
U. Garitaonaindia, N. Carbajal, M. Isasa, F. Mujika

Materiales Compuestos (2022). Vol. 07 - COMUNICACIONES MATCOMP21 (2022), (Núm. 2 - Aplicaciones Industriales - Caracterización), 178

Abstract
This paper analyses the two-plane bending test to characterise the behaviour of unidirectional composite laminates. This test consists of a flat plate supported at four points to which a point force is applied at the centre. Currently, this configuration is not mathematically solved for orthotropic materials. Initially, the displacements and bending moments produced in plates of isotropic material have been analysed by means of numerical simulation and analytical approach. The results obtained have been corroborated with other works published in the scientific literature. Subsequently, the numerical models and the analytical development have been applied to plates formed with orthotropic material, in the configuration of the two-plane bending test. For this purpose, rectangular plates with different aspect ratio have been analysed in order to obtain different stress ratios along the fibre and perpendicular to it. Finally, the results obtained both by numerical simulation and by the analytical approach have been compared with experimental tests carried out on unidirectional composite specimens made of epoxy matrix and carbon fibre.
Abstract
This paper analyses the two-plane bending test to characterise the behaviour of unidirectional composite laminates. This test consists of a flat plate supported at four points [...]
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Fast and efficient manufacture of carbon fiber aeronautical preforms by using direct resistive heating
A. Iriarte Legarreta, M. Segura, R. Mezzacasa, B. Canflaca

Materiales Compuestos (2022). Vol. 07 - COMUNICACIONES MATCOMP21 (2022), (Núm. 2 - Aplicaciones Industriales - Caracterización), 172

Abstract
The manufacture of preforms for composite structures is predominantly carried out in large hot drape forming facilities. However, these conventional heating sources are very inefficient since a large part of the heat provided is transferred to the molds in which the preforming process is carried out. This implies long heating and cooling times. In the current context in which it is essential to reduce the carbon footprint of each component, the reduction in the energy needed and in the cycle times to obtain competitive processes is fundamental. In this context, Tecnalia has developed an advanced preforming cell for the manufacture of dry fibre preforms for RTM or infusion components by applying direct resistive heating. The application of a current directly on the material to be processed has the advantage of avoiding the heating and cooling of molds and obtaining results in a much faster and more efficient way than with the methods traditionally used until now. The application of heating only to the preform guarantees the obtaining of much shorter cycle times, and a reduction in energy consumption of up to 90%. This results in a reduction in the cost of the process associated with lower energy consumption and shorter cycle time. The resistive preforming offers results of a quality of the preforms similar to that of conventional hot drape forming technology, being also a repetitive process, which has been validated by impregnating preforms tested under flight conditions.
Abstract
The manufacture of preforms for composite structures is predominantly carried out in large hot drape forming facilities. However, these conventional heating sources are very [...]
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Evaluation of impact resistant composites for aircraft cockpit
R. Rocha, L. Pina, M. Gomes, J. Sousa

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 1 - Avances en Materiales Compuestos. Nuevos Campos de Aplicación.), 58

Abstract
Several impact events are known to affect the aircrafts airworthiness, namely, bird or hail strike and impacts from uncontained engine rotor failure or other metal debris. Therefore, improvement of impact protection solutions for the cockpit, front and lateral panels is required, capable of endure such events without weight penalty. Several manufacturing technologies were implemented and tested up to 200 m/s with a compressed air gas cannon assembled a smooth bore barrel of 4 meters. Steel and hail spheres were used as projectiles and driven with a sabot. A digital chronograph and two high-speed cameras provide the impact velocities. Ultrasonic phase-array and x-ray inspection were performed to assess the damage. Evaluation was performed by comparison with the provided baselines. Among the tested solutions, carbon fibers impregnated with an epoxy resin doped with carbon nanotubes presented the best energy absorption performance for hail impacts. On the other hand, for metal sphere impacts, a fiber metal laminate solution made of aluminium and Dyneema® present the best behaviour.
Abstract
Several impact events are known to affect the aircrafts airworthiness, namely, bird or hail strike and impacts from uncontained engine rotor failure or other metal debris. [...]
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AUTOMATIZATION IN NEW MANUFACTURING APPROACHES FOR BODY SHELL APPLICATIONS
A. Gutierrez, L. Mera, L. Carral, I. Coto, F. Ansedes, M. Plettig, S. Renner

Aitana Gutierrez's personal collection (2022). 2

Abstract
The transport sector has exerted and continue to be the driving force for the development of new materials and lightweight solutions. The present study focuses on the work developed in a European project (CARBODIN https://carbodin.eu/) where one of the main objectives is to develop innovative and affordable solutions for advanced car body shells. Thus, contributing to the development of the next generation of passenger trains that will be lighter as well as more energy- and cost-efficient. Composite materials appear to be one of the most promising candidates to attain these ambitious targets. Therefore, new strategies to achieve greater automation are presented as novel manufacturing routes and offer a cost-effective industrial solution. This study has allowed the integration of unconventional technologies, such as AFP, within conventional production systems, such as VIP, which is the key to developing sustainable units, overcoming the common difficulties associated with processing and achieving the modularity of the manufacturing process and the reduction of the weight of the final rail structure. For this reason, a comparison of the manufacture of both monolithic composites and sandwich structures have been obtained through the VIP process, manufactured in an automated and manual way. Several automated approaches have been studied, with the choice of the robotized lay up of bindered dry fibers. An out of autoclave manufacturing was assisted through different monitoring technologies such as resin arrival sensors and thermography in order to ensure high quality components.
Abstract
The transport sector has exerted and continue to be the driving force for the development of new materials and lightweight solutions. The present study focuses on the work [...]
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Comparative study on methods for obtaining voids, fibre and resin percentages in composite materials
M. Jiménez, P. Morón, D. Alfaro, J. Sánchez, . K.Muñoz, F. Simón, L. Vicente

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 1 - Avances en Materiales Compuestos. Nuevos Campos de Aplicación.), 59

Abstract
Manufacturing quality in composite laminates is one of the key aspects to have in consideration when producing aerostructures. For composite structures quality evaluation, an iterative process of qualification of the first items manufactured is often followed. Thus, the manufacturing process parameters can be tuned until achieving an incremented maturity level that ensures the structure mechanical properties present values within the defined quality standards. Volume fraction of voids (pores), resin and fibre is part of the set of properties that must be verified, especially in novel and/or low cost manufacturing processess that can affect the structural behaviour. The ability to obtain results depending on the technique used for testing becomes very important at this point. This study proposes a comparative analysis of the measurement of voids, fibre and resin percentage on carbon fibre reinforced polymers by automated image analysis technique and acid digestion method, varying parameters of the test procedure with the purpose of evaluating their influence in the correct determination of volume fractions. The use of different methods and parameters allows to analyze comparatively the different results obtained and shows advantages and disadvantages of both methods as well as provides valuable information on the best practices for correct test execution following each procedure.
Abstract
Manufacturing quality in composite laminates is one of the key aspects to have in consideration when producing aerostructures. For composite structures quality evaluation, [...]
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Composite materials for the railway sector
M. Ordóñez, X. Valor, . C.Eraso, M. Seco, I. Echevarria, E. Bellvert, R. Villoria

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 1 - Avances en Materiales Compuestos. Nuevos Campos de Aplicación.), 77

Abstract
The intrinsic properties of composite materials make their use especially attractive for different industries, especially in the transport sector, where the reduction of weight and the consequent reduction of energy consumption are key factors. The main problem to implement composite materials within the railway sector is that each component and assembly in the complete train needs to fulfil the Fire, Smoke and Toxicity (FST) requirements described in standard EN 45545-2. At present, there are very few resins that comply with this regulation, due to the recent incorporation of this normative which was approved in 2013 and the resins that manage to comply with it are highly doped that it is difficult to obtain good manufacturing results with them. A preliminary selection of the materials validated by the railway industry will be carried out. Moreover, it will be necessary to develop a study and characterization of the different options in order to find the best possible choice according to the different applications. This way, materials will be evaluated in terms of processability, physical-chemical and mechanical properties. For preimpregnated materials, the properties obtained with different curing processes will be analyzed: Oven Cure and Autoclave (only as a comparative reference). The objective is to get a preliminary evaluation and compare the different materials between each other.
Abstract
The intrinsic properties of composite materials make their use especially attractive for different industries, especially in the transport sector, where the reduction of weight [...]
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Manufacture of aluminum composite materials reinforced with carbon fibers
J. Bedmar, B. Torres, M. Sanchez, P. Rodrigo, A. Ureña, J. Rams

Materiales Compuestos (2022). Vol. 05 - Comunicaciones Matcomp19 (2021), (Núm. 3 - Procesos de Fabricación – Materiales Funcionales.), 79

Abstract
The aluminum and its alloys stand out thermal conductivity and good mechanical properties, which, combined with a low density, high environmental resistance and a reasonable cost, makes them very suitable for multiple applications. In spite of this, different applications, such as In the case of LED-based lighting systems, it is necessary to increase the thermal conductivity; while the transport sector demands to improve its mechanical properties, like rigidity and strength. To meet these requirements aluminum composite materials reinforced with unidirectional carbon fiber and woven have been developed, initially manufacturing pieces of simple geometry, but coming to manufacture complex elements, such as luminaires or clutch housings, with improved mechanical and thermal properties compared to those manufactured without reinforcement meeting the demands of this class of applications. The process used has been based on the injection of high pressure aluminum on the dry tissue giving rise to a very fast and efficient process in which the formation of fragile interfaces is avoided and there are no viscosity problems, such as those that occur in the manufacturing processes most commonly employed. In conclusion, through a process of high pressure injection of aluminum on carbon fibers, unidirectional or fabrics, pieces of metal matrix composite material that have superior thermal and mechanical properties with respect to uncoated aluminum alloys have been manufactured.
Abstract
The aluminum and its alloys stand out thermal conductivity and good mechanical properties, which, combined with a low density, high environmental resistance and a reasonable [...]
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Modeling and analysis of hybrid energy absorption devices for aircraft structures
J. Paz, J. Díaz, L. Romera

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 1 - Avances en Materiales Compuestos. Nuevos Campos de Aplicación.), 63

Abstract
The design of structures according to impact protection or crashworthiness criteria aims for maximum kinetic energy dissipation through progressive component collapse, with the ultimate goal of minimizing the acceleration peaks suffered by occupants. One of the common trends for reducing accelerations in aircraft structures is that of including collapsible absorbers within the main structural design. This communication focuses on the crushing analysis through numerical simulation of thin-walled hybrid energy absorbers. These absorbers combine a confining metallic tube with a core made from composite materials and high-density structural foam. The components are characterized with different crashworthiness metrics, including the energy absorbed by the device or the peak force during the crushing process. The usage of hybrid elements delivers a significant enhancement compared to the single-component counterparts, improving the structural behavior of the aircraft under impact loading and better protecting the occupants. Results show that, at the component level, the usage of inner reinforcements modifies the collapse mechanism of the specimen and increases the specific energy absorption of the device, mainly rooted in the interaction effect between the core and the confining tube.
Abstract
The design of structures according to impact protection or crashworthiness criteria aims for maximum kinetic energy dissipation through progressive component collapse, with [...]
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FEM simulation of stiffened structures with pultruded carbon fibre profiles
R. Páez, M. Vázquez, . P.Astola

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 1 - Avances en Materiales Compuestos. Nuevos Campos de Aplicación.), 64

Abstract
Simulation of composite structures through Finite Elements Method (FEM) is widely used in the aeronautics sector to reliably predict its performance. The incorporation of new materials with enhanced properties, and also new manufacturing processes usually require the use of such tools for validation. This work has been focussed on studying an emerging technology such as Pultrusion for stiffeners manufacturing. For this, it has been used a demonstrator based on a common airframe structure, panels stiffened with profiles. This time, the classic stiffener manufactured using prepreg and autoclave cured has been replaced by stiffeners manufactured by Pultrusion. For that purpose, it was manufactured flat panels using prepegs and autoclave curing, for subsequently bond L shaped high resistance carbon fibre profiles manufactured by Pultrusion. Furthermore, FEM simulations were conducted over these coupons for three different mechanical testing conditions, tensile, compression and shear, aiming to determine the capability of these methods for simulating reliably the mechanical performance of pultruded materials on such above-mentioned structures. The results obtained in this work have been used for model parameter adjustments to obtain reasonable correlation levels, enabling the future usage of Pultrusion technology in the stiffener profiles manufacturing.
Abstract
Simulation of composite structures through Finite Elements Method (FEM) is widely used in the aeronautics sector to reliably predict its performance. The incorporation of [...]
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Enhanced interlaminar fracture toughness of woven carbon fabric/epoxy composites by interleaving fluffy CNT veils
Y. Ou, C. González, J. Vilatela

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 1 - Avances en Materiales Compuestos. Nuevos Campos de Aplicación.), 65

Abstract
While fiber reinforced polymer (FRP) composites are widely utilized in structural components due to their favorable mechanical properties, delamination between reinforcing plies remains a major problem, weakening the composite structure and limiting more widespread applications of FRPs. Carbon nanotubes (CNTs) carry the promise of enhancing this poor out-of-plane mechanical performance, although their integration has been challenging. In this work, macroscopic CNT veils with controlled nano-meso structure were drawn from the gas-phase using a semi-industrial process and then integrated into woven carbon fiber/epoxy matrix composites utilizing a facile and scalable approach. Interlaminar fracture toughness (ILFT) of the resulting composites was determined in Mode-I (opening mode) test. Additionally, crack propagation and interlaminar toughening mechanisms were systematically analyzed by means of optical microscope, SEM, and Raman analysis. The results showed that mode I ILFT was improved as much as 60% when interleaving as-received fluffy CNT veils and also revealed that interlaminar crossing between CNT veil/CF interfaces is of paramount importance in toughening mechanism.
Abstract
While fiber reinforced polymer (FRP) composites are widely utilized in structural components due to their favorable mechanical properties, delamination between reinforcing [...]
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A new approach to attenuate low velocity impact damages on CFRP structures
L. Amorim, A. Santos, J. Nunes, J. Viana

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 1 - Avances en Materiales Compuestos. Nuevos Campos de Aplicación.), 66

Abstract
Carbon Fibre Reinforced Polymers (CFRP) have been widely used in advanced markets, such as, the aeronautic, aerospace and military ones. Despite their extraordinary mechanical properties and low density, advanced composites, due to their intrinsic brittleness and layer-by-layer nature, present some vulnerability when submitted to impact, dynamic and flexural loading. Low velocity impacts (LVI) are one of the most dangerous events that composite laminate can face in their life time. These solicitations may develop imperceptible internal laminate damages, namely delaminations, that tend of propagate in service, compromising part performance. In order to improve interlaminar crack propagation, some works were already carried out using interleaved thin veils between laminate layers to enhance the interlaminar Mode I and II fracture toughness. In this work, a study was carried out on the distribution of stresses across the thickness of a carbon/epoxide laminate typically used in structural aircraft components, to define between which specific layers would be better to interleave thin veils made from four different materials (glass, carbon, aramid and polyester) to achieve better LVI damage tolerance. Samples made from the selected structural carbon/epoxy laminate were then produced by vacuum bag infusion with those thin veils located between their most appropriated layers to be submitted experimental testing and compare their mechanical and LVI performances with those without using interleaved veils. All studied laminates were observed under scanning electron microscopes (SEM) for assessing their processing quality and submitted to interlaminar shear strength (ILSS) and LVI tests to evaluate their delamination resistance and impact response, respectively.
Abstract
Carbon Fibre Reinforced Polymers (CFRP) have been widely used in advanced markets, such as, the aeronautic, aerospace and military ones. Despite their extraordinary mechanical [...]
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Interlaminar fracture toughness of 3D printed continuous carbon fibre- reinforced polyamide
M. Iragi, C. Pascual-Gonzalez, A. Esnaola, J. Aurrekoetxea, C. Lopes, L. Aretxabaleta

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 1 - Avances en Materiales Compuestos. Nuevos Campos de Aplicación.), 67

Abstract
In this study, the interlaminar fracture toughness of 3D printed continuous carbon fibre-reinforced polyamide was characterized under Mode I and II loadings. 3D printing of fracture test samples presents difficulties, mainly shrinkage and excessive warping. To minimize these effects, two solutions were developed. The results show that the Mode I interlaminar fracture behaviour of the printed samples is similar to that obtained by hot compression moulding. In mode II, however, propagation is not effective due to the type of microstructure of the 3D printed material. The hot pressing of the printed material reduces the fracture toughness under Mode I, but significantly improves the fracture toughness under Mode II. The causes of these behaviours are discussed in the paper.
Abstract
In this study, the interlaminar fracture toughness of 3D printed continuous carbon fibre-reinforced polyamide was characterized under Mode I and II loadings. 3D printing of [...]
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Large Lifting surface optimized in cost and weight, for high rate production
A. Pérez, V. García, M. Motilva, P. Nogueroles

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 1 - Avances en Materiales Compuestos. Nuevos Campos de Aplicación.), 68

Abstract
Commercial aviation is evolving towards high production rates in an increasingly competitive environment. The structures of composite materials offer the best performance in weight but, in this scenario, they have to do it with robust industrial processes and competitive costs. With this objective and thanks to the contribution of the Spanish goverment trough CDTI, a very effective collaboration was organized between Airbus, pushed by the initiative of the spanish comercial part, FIDAMC, the Technology center linked to Airbus in Spain, MTorres, a recognized supplier of composite industrial equipment and Hexcel, one of the lead suppliers of high performance composite materials. The Project, known as HDPREG, has allowed, trough a complete test pyramid, the development of a material, a new automatic lamination head and a manufacturing process, all adapted for the production of large lifting surface parts for aircraft use and compatible with the mentioned requirements. As a final exercise, beyond the scope of the project, FIDAMC, MTORRES and HEXCEL, funded the manufacture of an 18 m real-scale component, demonstrating the very high lamination productivity, as well as the feasibility of the application of the new material and the innovative manufacturing processes to meet the demands in terms of cost, weight, and industrial robustness.
Abstract
Commercial aviation is evolving towards high production rates in an increasingly competitive environment. The structures of composite materials offer the best performance [...]
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Design and optimization of a self-deployable composite structure
P. Fernandes, R. Marques, R. Pinto, P. Mimoso, J. Rodrigues, A. Silva, J. Tavares, G. Rodrigues, N. Correia

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 1 - Avances en Materiales Compuestos. Nuevos Campos de Aplicación.), 69

Abstract
Self-deployable composite structures are attractive for space applications as they provide lightweight, low cost and simple solutions that can replace mechanical systems. These structures can be folded and use the stored strain energy to promote a self-deployment event. However, these structures present design, manufacture and optimize challenges. This article describes the process of designing and optimizing an elastic-hinge, for a telecommunication satellite considering both structural and frequency requirements using finite element analysis, manufacturing and experimental testing. Furthermore, the paper details the sequence of optimization algorithms that were used to produce a solution capable of meeting the original design specifications. The structural assessment consists of the elastic-hinge numerical modelling during the folding process, by means of an explicit formulation. This model correlates well to the experimental test data and was used to evaluate the damage installed in the hinge using a pletfora of damage criteria. The frequency analysis considers the numerical modelling of a system constituted by the elastic-hinge and a telecommunication satellite antenna. This model was used to estimate the natural frequency of the system. Results show that a design methodology which uses a genetic algorithm (GA) for a global search, followed by a particle swarm optimization (PSO) method for a local search provides a good approach to the optimization problem. It is also shown that the efficiency of these algorithms can be maximized by tailoring their architecture and internal parameters.
Abstract
Self-deployable composite structures are attractive for space applications as they provide lightweight, low cost and simple solutions that can replace mechanical systems. [...]
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3D-printing self-healing composite polymer reinforced with carbon nanotubes
R. Calderón-Villajos, A. López, L. Peponi, J. Manzano-Santamaría, A. Ureña

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 1 - Avances en Materiales Compuestos. Nuevos Campos de Aplicación.), 70

Abstract
EMAA copolymer neutralized with sodium salt is a type of ionomer with self-healing abilities. This polymer has been used as raw material for the manufacturing of nanocomposite material by the addition of multiwall carbon nanotubes (MWCNTs). The optimization of the extrusion process, as well as the mixing and dispersion of the nano-reinforcement in the polymeric matrix during extrusion, deals with the manufacturing of a homogeneous reinforced filament. The obtained filaments were used afterwards as feeding materials of a 3D polymer printing machine and tensile test samples were manufactured. Mechanical properties of both unreinforced and reinforced samples were tested. The MWCNTs-reinforced samples exhibited higher mechanical properties without affecting its self-healing ability.
Abstract
EMAA copolymer neutralized with sodium salt is a type of ionomer with self-healing abilities. This polymer has been used as raw material for the manufacturing of nanocomposite [...]
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Manufacturing and study of the properties of polymer matrix composites reinforced with magnetite and carbon black for electromagnetic shielding applications
A. Posada, J. Barrado, D. Téllez, J. Roa-Rojas, . A.Rosales-Riveros, N. Salazar-Henao

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 1 - Avances en Materiales Compuestos. Nuevos Campos de Aplicación.), 72

Abstract
This work describes the production and morphological, structural, and magnetic characterization, as well as the electromagnetic shielding properties of polymeric based composites reinforced with different ratios of magnetite and carbon black. This kind of composites are used not only for the manufacture of electronic elements such as shape memory polymers, sensors and transducers, but especially for the production of electromagnetic shielding materials in both passive defense and civil construction applications; Buildings, vehicles or airplanes. The melt mixing method and vulcanization procees was followed for the manufacture of the composites.Composite materials with natural magnetite and synthetic magnetite have been considered separately. Reinforcements fillers were added in different ratios. The morphological analysis carried out by FESEM demonstrates the differences in size and shape of the fillers.Through the Raman and XPS spectroscopy the interface matrix-fillers was studied. The magnetite content, as well as its source, directly affect the magnetic behavior of the composites. The electromagnetic shielding properties were evaluated in the X band of frequency (8-12 GHz) and K band (18-27 GHz), with attenuations greater than 34 dB for the composites with the highest amount of magnetite.
Abstract
This work describes the production and morphological, structural, and magnetic characterization, as well as the electromagnetic shielding properties of polymeric based composites [...]
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Development of new high performance PUR resin formulations for processes of high production rate of structural components
O. Echeverria-Altuna, O. Ollo, I. Harismendy, A. Eceiza

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 1 - Avances en Materiales Compuestos. Nuevos Campos de Aplicación.), 75

Abstract
The deployment of composites for lightweight solutions in the automotive market is still emerging due to the production cost of these components and the limited production capacity of current manufacturing technologies. The development of more reactive formulations for processes that allow to increase production rates and reduce process times to a few minutes are arousing great interest, such as the HP-RTM (high pressure RTM) and the HP-CRTM (RTM compression). In the case of RTM resins, ultra-fast (2-5min) and low viscosity curing formulations are sought to optimize the curing and injection cycles to the maximum. The technology based on polyurethane resins (PUR) offers against other alternatives the advantage of having great tenacity and resistance to fatigue which makes it especially attractive for elements subject to impacts or cyclic loads such as suspension elements. This work, based on simulations, has determined an optimal value of the PUR viscosity for RTM. In addition, a preliminary analysis of the curing kinetics of a commercial PUR resin has been carried out. The results indicate that the resin evaluated is not viable for the process due to its high reactivity at the beginning of curing, so that work will continue on the search for more latent PUR solutions for RTM.
Abstract
The deployment of composites for lightweight solutions in the automotive market is still emerging due to the production cost of these components and the limited production [...]
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Manufacturing and mechanical characterization of natural fibre reinforced biocomposites. Application in a small wind turbine
J. Vallori, G. Vargas, A. Boyano, A. Lopez-Arraiza

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 1 - Avances en Materiales Compuestos. Nuevos Campos de Aplicación.), 76

Abstract
In this work, new biocomposites were manufactured and mechanically tested. A resin from natural resources (SuperSap®) was reinforced by a bidirectional flax and oak wood laminates. Normalized tensile and three-point bending tests were performed and it was observed that the oak wood laminates in the outer layers give a great aesthetic finish and the tensile stiffness is also increased a 2% compared to the flax reinforced biocomposite. Regarding the results of three-point bending, the oak laminates in the core provide a greater flexure breaking strength, which is a 10% higher than the flax reinforced biocomposite. SEM micrographs show both the accuracy of the infusion process and the good adhesion of the different natural fibres and bioresin. Finite Element simulations (FEM) were carried out at different pressures generated by three wind velocities (Vwind= 3, 8 and 11m/s). Both tension and deformation results show that the structural integrity of the biocomposite wind blades is not compromised. Finally, the real tests in the wind tunnel have validated the use of the developed biomaterials in manufacturing blades for small wind turbines.
Abstract
In this work, new biocomposites were manufactured and mechanically tested. A resin from natural resources (SuperSap®) was reinforced by a bidirectional flax and oak wood [...]
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Monitoring of multi-material structures for offshore applications with fiber optic sensors
T. Grandal, D. Pérez, S. Dasilva, R. Mano, S. Fraga, L. Mera, E. Rodriguez

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 1 - Avances en Materiales Compuestos. Nuevos Campos de Aplicación.), 78

Abstract
The development of renewable energies is a fundamental need to meet the ambitious energy targets demanded by industry and the European Union in the coming years. In the case of offshore wind energy, it has certain limitations due to its relative youth and associated costs, especially in the maintenance, operation and repair operations. Within the project, that includes this work, has developed a new multi-material component with high structural requirements for the offshore wind sector. A combination of steel and composite, manufactured by filament winding, with a system of protection of biofouling and corrosion, will be validated in a real conditions test in the experimental zone of INEGA (A Coruña), by a demonstrator to scale 1:5. For real-time monitoring of the multi-material structure, a monitoring system has been developed based on fiber optics sensors type Bragg Grating (FBG), integrated in this structure. This monitoring system includes sensors of corrosion, temperature and deformation. This paper shows the development and characterization of these sensors at the laboratory level against mechanical, thermal tests and study durability in marine environment. In addition, it describes the integration of the monitoring system in the demonstrator and its response during the validation phase.
Abstract
The development of renewable energies is a fundamental need to meet the ambitious energy targets demanded by industry and the European Union in the coming years. In the case [...]
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Optimization of direct dissimilar joining metal – thermoplastic composite for automotive and aerospace applications
L. Blanco, P. Rey, A. Pedreira, M. Coto

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 2 - Procesos de Fabricación y Técnicas de Unión), 109

Abstract
The transport industry is dominated by the challenge on lightening the weight due to environmental restrictions and cost reduction. The use of different materials and multi-material designs provide a great opportunity to develop products capable of meeting this challenge. Critical aspects to be considered in multi-material manufacturing are surface preparation and dissimilar joining. The multi-material joining metal-composite thermoplastic (CTP) is critical for different aspects such as low adhesion due to a low chemical affinity or corrosion problems in the case of the use of carbon fiber reinforced composites. On the other hand, laser texturing is one of the most promising techniques to create surfaces with controlled roughness, manufacturing in a single step and improving metal-CTP adhesion, without the need to use adhesives. This work, developed within the framework of the European COMMUNION project (GA680567), addresses the optimization of the direct joining process between different high-performance metals and thermoplastic composite cintas. The study deals with surface preparation using laser texturing, the study of different joining strategies and the characterization of joints using different techniques and Single-Lap Shear tests. Depending on the texture, type of materials or manufacturing strategy, the strength of the joint is improved by 50-200%, achieving structural strength values (> 10MPa) in the optimized joints.
Abstract
The transport industry is dominated by the challenge on lightening the weight due to environmental restrictions and cost reduction. The use of different materials and multi-material [...]
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Use of biogenic silica nanoparticles derived from biomass in polymeric formulations and their applications
H. Aguilar, D. Conceição, A. Barros, V. Bouça, M. Ornelas, R. Malgueiro, A. Carvalho, A. Portela, C. Silva, E. Döpelheuer, S. Grishchuk, L. Gryshchuk, M. Gilberg, B. Wetzel

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 3 - Materiales bioinsipirados), 128

Abstract
In view of moving towards a post-petroleum society, several attempts are being made to reconcile resource scarcity and environmental objectives with the use of biomass for multisector industrial applications. ReInvent project aims to deliver novel bio-based materials as additives/bio-nanofillers for insulation and structural products used in buildings and lightweight soft foams for vehicle interior products. The extraction/fractionation processes from biorefineries aim to provide sustainable raw-materials for the development of functional bio-nanosilica particles to be incorporated in polymeric matrices, to produce new advanced cellular and composite materials. Particularly, this work lies on the extraction, purification and characterization of bio-nanosilica extracted from rich-silicate residues (e.g. rice husks, hempshells, hempfibres, oil pressing solid residues). The extracts were examined using scanning electron microscopy, and their textural properties were evaluated by surface area and pore measurements. Influence of bio-nanosilica on the rheological behaviours of biobased furan and greened indirect polyurea resins was studied in terms of possible prepregging of both resins. A comparison of influence of bio-nanosilica dispersed in isocyanate and waterglass (WG) components on the chemo-rheological behaviour of the resin was performed, showing a strong increase of viscosity at ambient conditions, but no obvious difference at typical processing temperatures between 60‑90 °C.Thus, similar processing conditions, improved handling and storage ability of related prepregs were ensured. Obvious reduction of reaction speed, confirmed by slower increase of viscosity, was characteristic for IPU resin containing bio-nanosilica particles, especially when dispersed in WG, potentiating longer shelf-life of such highly reactive prepregs at cold storage conditions.
Abstract
In view of moving towards a post-petroleum society, several attempts are being made to reconcile resource scarcity and environmental objectives with the use of biomass for [...]
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Bioinspired hybrid materials for reduction of viscous drag in ships
A. Rodríguez-Ortiz, J. Suárez-Bermejo, P. Pinilla-Cea

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 3 - Materiales bioinsipirados), 117

Abstract
Nature has evolved structural materials along millions of years of incremental changes to fulfil functional requirements of very different situations. Let´s take as an example the sharks, one of the best adapted species for swimming across the oceans, and their smooth skin that is composed of millions of small scales (denticles), with complex geometries formed by sharp spines and micro-grooves aligned with flow direction, varying in size and shape at different locations of the sharkskin. The purpose of this microstructure is to reduce the viscous drag produced by the water when it adheres to the hull forming the fluid boundary layer, which can stick out the added mass to the weight of the fish and increase dramatically its peak speed. Inspired by this natural solution, we have started the design of a bioinspired new material, to be incorporated to the hull wet surface, reducing the viscous drag and increasing the velocity and the efficiency (less fuel consumption) of the ship. In this way, it will be easier to control the green effect gas emissions while sailing. We present the development of this new bioinspired, hybrid material with scales obtained by additive manufacturing using polymeric materials. To control the orientation of the denticles respect to flow direction, the scales have been mounted on a substrate of hydrogel, who interact with the fluid field of pressures to adapt the angle of the moving scales as the velocity increases. No mechanical devices are needed, as the hydrogel act as a nonlinear spring accommodating the movements of the scales. CFD code helps in the development of the most efficient shape and coating design. A water channel has been developed to measure the actual forces acting on the surface of coated panels.
Abstract
Nature has evolved structural materials along millions of years of incremental changes to fulfil functional requirements of very different situations. Let´s take as [...]
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Application of agroforestry residues in polymeric composite materials
X. Pedras, G. Piñeiro, . M.R.Castilla

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 3 - Materiales bioinsipirados), 119

Abstract
The lignocellulosic materials can be employed in the manufacturing of materials compound by a polymeric matrix due to its characteristics and peculiarities. Especially, to come from a natural sustainable resource, abundant and local character, with a low environmental impact and also low cost. In the present it is possible to find in the market industrial solutions, however, usually these materials come of byproducts generated in wood transformation industry and that enter in competence with other industry process like wood board manufacturing. Nevertheless, these materials can also be obtained from the valorisation of different residues generated in local agroforestry crops, which besides it have a low level of exploitation. They are evaluated to the Galicia Euroregion North Portugal, the different natural sources of these materials and its analysed the availability that exists and the technology available to its collection. They are analysed too, the different phases and processes required to do the preparation of these materials to its use in injection, extrusion and rotomolding composites and, especially, in relation to material moisture content and its morphological characteristics. In most of the cases, these residues present difficulties to be valorised so that, in many cases it is resorted to its direct burning, generating environmental problems. Even though, the most part of these materials are susceptibles too to be energy valorised, it is possible to combine in the same industrial process the combined production of natural fibres and material to energy production.
Abstract
The lignocellulosic materials can be employed in the manufacturing of materials compound by a polymeric matrix due to its characteristics and peculiarities. Especially, to [...]
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Study of the influence of surface treatments in kraft paper for the compatibilization with thermoplastic polymers
F. Leite, . C.Mota, . L.Nobre, . J.Bessa, . F.Cunha, . C.Costa, . J.Teixeira, . R.Fangueiroc

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 3 - Materiales bioinsipirados), 126

Abstract
The transports industry has been presenting a set of solutions that integrates natural fibers and their compatibility with structural materials, like polymers. However, it is fundamental to ensure the fulfillment of mechanical requirements. One of the main reasons that is driving the use of this type of fibers, instead of synthetic fibers, is related with the some actual trends, such as weight reduction, which is linked with its lower density. Moreover, weight reduction also contributes, indirectly, to the sustainability and decrease of greenhouse gases emissions, since it makes possible to reduce the fuel consumption of transports.However, due to the different polarities verified between apolar thermoplastic polymers, such as polypropylene (PP), and natural fiber reinforcements, such as kraft paper, a study of the effect of physical and chemical surface treatments was carried out in order to verify their influence on the fiber-matrix interface properties. The physical process, corona treatment, was applied in the kraft paper with different discharge dosages, while the chemical treatment was performed through the use of several alkali solutions with different concentrations of NaOH. The obtained results from the performed tests shows that the alkali solution treatments improved, up to 57%, the mechanical properties of tensile strength and Young Modulus of the composite material, comparatively with the effect of corona treatment on its surface. These results induce an increase of interface compatibility between the matrix and kraft paper.
Abstract
The transports industry has been presenting a set of solutions that integrates natural fibers and their compatibility with structural materials, like polymers. However, it [...]
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Viabilidad del uso de corcho aglomerado como núcleo de estructuras sandwich sometidas a impacto
C. Sergi, S. Sánchez-Saez, E. Barbero, J. Sarasini, F. Sarasini

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 3 - Materiales bioinsipirados), 131

Abstract
En la fabricación de estructuras sándwich de material compuesto, unas de las opciones más utilizadas como núcleo es el uso de espumas poliméricas. Debido al cada vez mayor esfuerzo en reducir el impacto medioambiental de los procesos industriales, existe un gran interés en incorporar materiales de origen natural que permitan disponer de fuentes renovables y que faciliten los procesos de reutilización y de reciclado. Una de las posibilidades para sustituir a las espumas poliméricas es el corcho aglomerado que presenta unas buenas propiedades mecánicas. No obstante, para que sea posible su uso como núcleo en estructuras sandwich es necesario conocer su comportamiento frente a cargas de impacto, tanto de baja como de alta velocidad. En este trabajo se compara el comportamiento de una espuma de PVC comercial con corchos aglomerados de diferentes densidades. Se ha analizado la fuerza, desplazamiento, energía absorbida y velocidad de perforación. Se ha observado que el comportamiento del corcho aglomerado puede ser similar al de una espuma polimérica convencional, aunque con un incremento de peso. Adicionalmente se ha puesto de manifiesto que el corcho aglomerado puede ser una alternativa mejor a las espumas poliméricas en aquellas aplicaciones que puedan verse sometidas a varios impactos sucesivos.
Abstract
En la fabricación de estructuras sándwich de material compuesto, unas de las opciones más utilizadas como núcleo es el uso de espumas poliméricas. [...]
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Manufacturing and testing of a new CFRP node bonded by adhesives for its use in bus structures
P. Gálvez, A. Quesada, J. Abenojar, . M.A.Martínez

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 2 - Procesos de Fabricación y Técnicas de Unión), 111

Abstract
In recent years exponential increase in the use of adhesives in industrial processes is observed. Nowadays these materials are used in applications as diverse as aerospace industry, automotive industry, railway industry or even civil construction. In the same way, the use of composite materials has grown enormously, especially in the aerospace industry, thanks to the benefits that this type of materials are able to provide, even as reinforcement. Current bus structures present serious problems of fatigue due to their rigidity, resulting in unexpected failures in certain nodes where stresses are concentrated. This work is part of a project that it is trying to provide more elasticity to the structure through the use of a new CFRP node joined by adhesives to the bus structure using polyurethane. The complex design of the node has caused numerous manufacturing problems. PLA node was manufactured using 3D printing for being used as a core. PLA node was covered layer by layer with CFRP by hand lay-up. In order to know the behavior of the whole set (CFRP node, adhesive and steel beams), four prototypes were manufactured and tested. Four point flexural test was carried out on the prototypes to validate the assembly. Results show the suitability and capacity of this new node concept to be used in bus structures. In recent years exponential increase in the use of adhesives in industrial processes is observed. Nowadays these materials are used in applications as diverse as aerospace industry, automotive industry, railway industry or even civil construction. In the same way, the use of composite materials has grown enormously, especially in the aerospace industry, thanks to the benefits that this type of materials are able to provide, even as reinforcement. Current bus structures present serious problems of fatigue due to their rigidity, resulting in unexpected failures in certain nodes where stresses are concentrated. This work is part of a project that it is trying to provide more elasticity to the structure through the use of a new CFRP node joined by adhesives to the bus structure using polyurethane. The complex design of the node has caused numerous manufacturing problems. PLA node was manufactured using 3D printing for being used as a core. PLA node was covered layer by layer with CFRP by hand lay-up. In order to know the behavior of the whole set (CFRP node, adhesive and steel beams), four prototypes were manufactured and tested. Four point flexural test was carried out on the prototypes to validate the assembly. Results show the suitability and capacity of this new node concept to be used in bus structures.
Abstract
In recent years exponential increase in the use of adhesives in industrial processes is observed. Nowadays these materials are used in applications as diverse as aerospace [...]
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Failure prediction in the neighbourhood of the hole in riveted joints with composite materials
A. Barroso, I. Silva

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 2 - Procesos de Fabricación y Técnicas de Unión), 105

Abstract
In riveted joints, typically two groups of failure mechanisms must be verified, those that affect the joining elements and those that affect the parts that must be drilled to be joined. In this last group, at least, three failure mechanisms must be taken into account: tension, shear and bearing. In each of these failure mechanisms, it must be verified that the component of the stress state responsible for the failure does not exceed a certain critical value that causes the failure. In the case of riveted joints with composite materials, the task is doubly complex. On the one hand, the stress state in the neighbourhood of the hole is complex, not only because of the non-linearity of the problem (the contact of the rivet with the walls of the hole) but also because of the non-isotropic nature of the material. This makes the stresses to have a strong dependence on the type of fiber, stacking sequence, and in general, on the mechanical properties (non-isotropic) of the laminate. On the other hand, the determination of the critical values, associated with each component of the stress state, responsible for each failure mechanism, is difficult to obtain, due to the fact that these strength values also depend on the particular orientation along the hole contour, where they are evaluated. In the present work, the stress state in the neighbourhood of the hole is evaluated in riveted joints with composite materials, analyzing different types of laminates, to serve as a basis for the prediction of the different failure mechanisms potentially acting.
Abstract
In riveted joints, typically two groups of failure mechanisms must be verified, those that affect the joining elements and those that affect the parts that must be drilled [...]
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Effects of dynamic fibre failure in unidirectional composites
I. Tena, I. Saenz-Dominguez, . J.Torre, L. Aretxabaleta, M. Sarrionandia, J. Aurrekoetxea

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 1 - Avances en Materiales Compuestos. Nuevos Campos de Aplicación.), 37

Abstract
The stress redistribution around a broken fibre is a substantial issue in longitudinal strength analysis of unidirectional (UD) composites. Most investigated models are based on a regular fibre packings and classical shear lag theory (static failure) that considers pre-broken fibers, where the dynamic aspects of brittle fiber failure are not considered. In the present work, Representative Volume Elements with random fibre packings were modeled by means of 3D finite element analysis, and simulated considering the event of dynamic fibre failure. Significant effects were observed on the stress concentration factor (SCF) and ineffective load length which are related to the fibre debonding length and the volume of matrix damage-plasticity zones. Hence, it can be concluded that an accurate representation of the stress redistribution after a fibre breakage event requires consideration of dynamic effects.
Abstract
The stress redistribution around a broken fibre is a substantial issue in longitudinal strength analysis of unidirectional (UD) composites. Most investigated models are based [...]
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Experimental evaluation of the coefficients of thermal expansion in a composite laminate using digital image correlation
J. Justo, E. Graciani, P. Zumaquero

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 1 - Avances en Materiales Compuestos. Nuevos Campos de Aplicación.), 74

Abstract
A procedure for measuring simultaneously the coefficients of thermal expansion (CET) in the in-plane and the thickness directions in L-shaped composite laminated samples is presented. Measurements are carried out using digital image correlation, from which the displacements in one of the faces of the samples are measured when de sample undergoes a temperature increment inside an oven. From the in-plane displacement measurements, the in-plane strain tensor components and the corresponding CTE are determined. Results show that the presented technique is capable of determining these CTE with high accuracy. Displacement measurements in the direction normal to the face, enables determining the rotation of the face and consequently the difference between the CTE in the thickness direction and the CTE in the in-plane direction affected by the curvature. Results obtained for the CTE in the thickness direction show, first, values significantly higher than the CTE of the material in the in-plane direction normal to the fibres and, second, a high dispersion from one stacking sequence to another. These discrepancies were expected and are caused by the misalignment of the fibres in the corner zone of the samples.
Abstract
A procedure for measuring simultaneously the coefficients of thermal expansion (CET) in the in-plane and the thickness directions in L-shaped composite laminated samples is [...]
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Polyethylene/boron composite materials in X-ray attenuation
J. Abenojar, S. Armentia, P. Gálvez, M. Martínez

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 1 - Avances en Materiales Compuestos. Nuevos Campos de Aplicación.), 73

Abstract
Currently, lead is used as radiological protection due to its high density in both, personal protection and shielding of equipment.. Iron, concrete or water can also be used to stop X-rays and gamma radiation. Shielding thicknesses are different since these materials have different densities. The used measurement is expressed in values of HVL (hemirreductor thickness in cm). In the case of lead, calculations to stop a photon with an energy of 3000 keV, give a shield of 1.5 cm in thickness. Therefore, a plate of 30x40 cm2 will weigh 20 kg, taking into account its density. LDPE and B composite materials are used as neutron shields: polyethylene, because of its high hydrogen content and boron for its ability to absorb neutrons. For this reason, the objective is to replace lead or other heavy materials by boron PMCs with lower densities for the manufacture of radiological shields. For this purpose, low density polyethylene films and LDPE composite films with 15-30 and 60% wt. of boron were made. Films have been manufactured by hot extrusion and compression. The test that has been carried out is to calculate the shielding effect on the aluminum of these films using X-rays provided by a laboratory equipment used for the characterization of materials. The results have shown a greater shielding for a multilayer system, than a single one with the same thickness.
Abstract
Currently, lead is used as radiological protection due to its high density in both, personal protection and shielding of equipment.. Iron, concrete or water can also be used [...]
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Homogenization procedures for the numerical analysis of eco-composites
L. Barbu, X. Martínez, S. Oller

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 1 - Avances en Materiales Compuestos. Nuevos Campos de Aplicación.), 62

Abstract
Homogenization procedures have been gaining more and more emphasis in the field of numerical analysis of composite materials. A homogenization procedure is based on the assumption that a set of equations or a representative element that can provide a response equivalent to the one provided by the actual material exists. A numerical multiscale homogenization will be shown where the behavior of the whole composite is obtained by a micromechanical study of the material components and their interaction within of the composite microstructure through an RVE model. The proposed formulation uses a non-linear activation function in the structural scale and its task is to predict if a material point in the structure is in linear or non-linear range. Because of this, the developed strategy only solves the microscopic Boundary Value Problem using the RVE for the non-linear integration points found. The procedure will be used in the nonlinear numerical simulaction of an eco-composite sanwich panel subjected to a four point bending test.
Abstract
Homogenization procedures have been gaining more and more emphasis in the field of numerical analysis of composite materials. A homogenization procedure is based on the assumption [...]
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Effect of hole interaction in the initiation of damage in laminates
A. Solis, S. Sánchez-Saez, E. Barbero

Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 1 - Avances en Materiales Compuestos. Nuevos Campos de Aplicación.), 38

Abstract
In open-hole laminates, when a second hole is made, the stresses and the damage evolution are modified. The main failure mechanisms in laminates subjected to compressive loads are fibre microbuckling and matrix breakage. In this work, the influence of the presence of a second hole in these mechanisms is analysed for two distances between holes. The Serial/Parallel Mixing Theory was used to model the elastic behaviour of the material and a Continuum Damage Model to represent the fibre microbuckling and matrix failure. The equations were implemented in a FEM code developed by the authors. The proposed model has been validated with results from the literature for a laminate with two holes positioned transversally to the applied load. In this problem, it was shown that the growth of the fibre damage is different from that of the matrix. The laminate is damaged mainly in the zone between the holes. When the distance between holes is reduced, both types of damage around the holes increase.
Abstract
In open-hole laminates, when a second hole is made, the stresses and the damage evolution are modified. The main failure mechanisms in laminates subjected to compressive loads [...]
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Development and characterization of high environmental performance composites of Bio-PBSA and short hemp fibers from different compatibilization strategies
R. Tejada Oliveros, J. Martinez, D. Sanoguera, N. Montanes, L. Carrillo

Materiales Compuestos (2022). Vol. 01 - Comunicaciones Matcomp17 (2017), (Núm. 1 - Comportamiento en Servicio de los Materiales Compuestos), 159

Abstract
In this research work, the effect of various compatibilizing agents on naturally sourced composites formed from poly(butylene succinate-co-adipate) - PBSA and short hemp fibers has been analyzed. Hemp has been employed as a natural reinforcement to obtain environmentally friendly composites, using biobased PBSA as a matrix. These composites were obtained from twin-screw extrusion and shaped by injection molding. To improve the poor compatibility between the matrix and lignocellulosic fibers, different compatibilizing agents were used, including a maleic anhydride graft copolymer (PBSA-g-MA), a copolymer based on itaconic acid (PBSA-g-IA) and dibutyl itaconate (DBI). The addition of these compatibilizers provided different levels of improvement with respect to the PBSA/hemp base compound. In relation to the mechanical properties, the addition of the copolymers significantly increased the maximum tensile stress, with values around 20 MPa, with respect to the 8,86 MPa of the PBSA/hemp uncompatibilized composite. The addition of DBI to the base blend led to an improvement in the elongation at break of 82% (3,51% elongation at break of the base blend versus 6,40% with the addition of DBI). These results are in agreement with those obtained in dynamic mechanical thermal analysis (DMTA), where the incorporation of hemp fibers and the combination of the different compatibilizers resulted in an improvement in stiffness over the entire temperature range.
Abstract
In this research work, the effect of various compatibilizing agents on naturally sourced composites formed from poly(butylene succinate-co-adipate) - PBSA and short hemp fibers [...]
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PET Bottles Recicled in Unsaturated Polyester Resins
P. Builes, M. Franco, M. Tous

Materiales Compuestos (2022). Vol. 03 - Comunicaciones Matcomp17 (2019), (Núm. 4 - País invitado: Colombia. Materiales Multifuncionales. Reciclaje y Sostenibilidad), 36

Abstract
The Company Andercol S.A.S recycles bottles of poly ethylene terphthlate (PET) to be use like a raw material in Unsaturate Polyester Resins (UPR) with economic, technical viability in a commercial level. For several years it is possible to control the collection, treatment and supply chain of PET bottles with the required quality. Actually Andercol has achieved consumption around of 10.000 bottles of PET by each ton of UPR, allowing to reduce pollution in landfills in more than 11.000 tons per year of PET.
Abstract
The Company Andercol S.A.S recycles bottles of poly ethylene terphthlate (PET) to be use like a raw material in Unsaturate Polyester Resins (UPR) with economic, technical [...]
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Study of the influence of flame retardant additives on ultra-violet curing thermosetting composites
. , N. Eulate

Natalia Gutiérrez's personal collection (2022). 1

Abstract
Fibre-reinforced polymer composites are materials capable of reducing weight while maintaining optimised properties in multiple applications. However, the use of composite materials is not suitable for all sectors, where the need for improved fire properties is highlighted. In the present study, a thermosetting matrix composed of UV-curable acrylic monomers and UV-transparent aluminium trihydrate (ATH) flame retardant fillers has been added to UV-transparent polyester resin for the manufacture of flame retardant composites. An in-depth study of the most suitable types of ATH-based flame retardant additives and possible synergistic combinations to improve the fire performance of the UV-curable composite has been carried out. Not only has the type of flame retardant been studied, but also the most suitable additive percentage to comply with railway sector regulations. The compatibility between the fillers and the matrix has been analysed by means of dielectric analysis, as well as the properties of the matrix and final composites against fire and mechanical properties.
Abstract
Fibre-reinforced polymer composites are materials capable of reducing weight while maintaining optimised properties in multiple applications. However, the use of composite [...]
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Rehabilitation of drinking water pipes with infusion and vacuum technology
F. Robles

Francesc Robles's personal collection (2022). 2

Abstract
In the bet of a circular economy to conserve, maintain and lengthen the value of water distribution and supply networks, infusion and vacuum technology used for on-site pipe manufacturing by means of carbon fiber is a safe, reliable and effective alternative for all of those pipelines, whose repair is a major challenge due to the complexity of action by traditional means. Excavations, interference with other services and social pressure exerted by excessive traffic cuts and supplies, are adversities that demand a cultural and strategic change towards the implementation of these innovative solutions, which are already a reality.
Abstract
In the bet of a circular economy to conserve, maintain and lengthen the value of water distribution and supply networks, infusion and vacuum technology used for on-site pipe [...]
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