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

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

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

  
  

  Abstract

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

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

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

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

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

  
  

  Abstract

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

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

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

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

  Materiales Compuestos (Online first).

  
  

  Abstract

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

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

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

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

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

  
  

  Abstract

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

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

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• 3D PRINTING OF BIO-INSPIRED CORES FOR OUT-OF-AUTOCLAVE SANDWICH STRUCTURES

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

  Materiales Compuestos (2022). Vol. 07 - COMUNICACIONES MATCOMP21 (2022), (Núm. 1 - Sostenibilidad y reciclaje - Fabricación), 164

  
  

  Abstract

  The design and manufacture of sandwich structures allow for many variants related to core and skin types, but their fabrication is very limited with conventional technologies. Recent advances in 3D printing are creating new design possibilities, such as bio-inspired structures with more complex cellular units than the current ones, functional gradients, and curved panels. The present work has focused on two aspects; 1) the efficiency of the core inspired by the trabecular structure of beetle wings versus the conventional honeycomb, and 2) the feasibility of integrating these new cores with carbon fiber/epoxy prepreg skins for out-of-autoclave curing.  The results show that the ONYX® 3D printing cores obtained by filament extrusion technology and the skins manufactured by out-of-autoclave curing show good skin/core adhesion. On the other hand, the results of the flexural tests have shown that the stiffness of the sandwich panel with the trabecular structure is better than that of one of the honeycombs and the strength in both cases is similar. However, where substantial differences have been found between the two types of cores is in the quasi-static puncture resistance, that of the trabecular structure being 60% higher.

  Abstract
  The design and manufacture of sandwich structures allow for many variants related to core and skin types, but their fabrication is very limited with conventional technologies. [...]

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

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

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

  
  

  Abstract

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

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

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