Documents published in Scipedia

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

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

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

  
  

  Abstract

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

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

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• 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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• 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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