Progressive Crush Response of Multi-Element Foam-Filled Preform RTM Structures, I: Architecture and Rate Effects

The application of composites in automotive structures has been a topic of increasing interest in recent years. This has largely been driven by the need for energy efficiency, increased safety requirements, economics related to fabrication, and the designers need for enhanced flexibility in form through increased materials and processing options. The main objective of this study was to investigate the effect of multi-element preform fiber architectures for a resin transfer molded structural (rather than the tube-type element usually used) component on compressive response, progressive crush and energy absorption. Six different architectures based on a stiffened plate-type structural shape were tested under two loading rates, and behavioral characteristics in terms of failure loads, energy absorption per unit structural deformation, and damage mechanisms were studied. Absorbed energy is seen to increase with loading rate, whereas failure load decreases or remains constant. It is seen that the increasing use of braided layers in the rib section increases efficiency in terms of energy absorption per unit deformation. The use of specially placed fabric layers is also seen to open avenues as triggers for controllable sequences of damage modes.