Thermosetting and thermoplastic impact attenuator under axial loading

Abstract

High-performance composites are generally fabricated with continuous fibre and fabric reinforcements embedded in a thermosetting resin. Using thermoplastic matrices, there are substantial reductions in forming time and labour. More recently, the availability of all-polypropylene composites, achieved using the same thermoplastic polymer for both the fibre and the matrix phase, is also increasing because of their recyclability. In this perspective, the work aims to study the mechanical behaviour of a new fully thermoplastic composite, first showing the results of an experimental campaign for the mechanical characterization of the material properties, then examining the behaviour of structures made of such material under axial loading to evaluate their energy absorption capability. The second part of this work is divided into two steps. In the first step, crush tests on simple tubes were performed. In the second step, the behaviour of a specific impact attenuator for a Formula SAE racing car was analysed. Using the same geometry, different material solutions were tested. Beside traditional thermosetting composite structure, a new fully thermoplastic composite and a hybrid solution were used taking into account various feasibility problems in the manufacturing phases. Even if the thermoplastic attenuator does not exhibit the same absorption capability of the thermosetting solutions, an interesting crushing mechanism was noticed: no more brittle failure with formation of debris, but a ductile progression with a load distribution very close to an ideal absorber.