Abstract

Abstract

Abstract

In the present paper a resins comparative study has been carried out, focused in out of die ultraviolet (UV) cured pultrusion process. In this new approach of the traditional pultrusion, the profile is cured outside the die with UV radiation. This fact implies th necessity of working with resins that present fast curing kinetics at the first stage of conversion in order to avoid the expansion of the profile at the exit of the die. Thus, with the aim of developing new photocurable resin formulations, it has been analysed the curing kinetics of an unsaturated polyester, epoxy-acrilate and a mixture of both resins (50%) with the photocalorimetry technique. Moreover, physical properties test and quasi-static compression test have been performed of profiles manufactured by UV pultrusion. The results prove that the mixture of both resins increase the conversion rate of unsaturated polyester, due to the faster curing kinetics of epoxy-acrylate. However, this fact has not been reflected in the percentage of voids, more elevated in the profiles manufactured by epoxy-acrilate. Nevertheless, the mixture presents higher energy absortion (SEA) values, about 22% higher than the unsaturated polyester and approximately 15% higher than epoxy-acrilate.

Abstract

Additive manufacturing, and more specifically FFF (Fused Filament Fabrication), makes it possible to manufacture complex designs that are difficult to manufacture using conventional processes that improve the mechanical behaviour of the component. In the present work, the axial impact behaviour of cylindrical tubes with a reentrant auxetic structure has been characterized. The material used is a polyamide 6 reinforced with short carbon fibre. As a reference, a solid thickness tube with the same outer diameter and mass as the tube with the auxentic structure has been designed. The main result is that the auxetic structure not only improves the specific absorption capacity, but also allows a progressive collapse thanks to the design and location of fault initiators. For this reason, 3D printing technologies have very attractive properties for the design of impact absorbers in the transport sector.