Static and dynamic axial crushing analysis of car frontal impact hybrid absorbers

Occupant safety and protection systems have risen as one of the foremost research fields in automotive engineering. Composite materials and synthetic foams are highly efficient car building materials due to their low weight and high strength, as well as their remarkable crashworthiness in combination with ductile metals. This paper compares the frontal crashworthiness capabilities of carbon-fiber reinforced polymers, glass-fiber reinforced polyamide, polyethylene terephthalate foam and cork conglomerates in combination with cold-formed steel polygonal tubes using quasi-static and dynamic numerical simulation verified with experimental results. Reinforcement materials are usually wrapped around the steel box, but in this research they are placed inside the box according to certain geometrical patterns and subjected to axial crushing. Non-linear effects, contacts, strain rate dependent effects, geometric imperfections and residual stresses are taken into account to achieve realistic results, which show a remarkable improvement in terms of energy absorption in most cases, and a quality agreement with experimental data. A combination of a glass-fiber reinforced polyamide padding and a steel box has offered the best results, and a detailed study of its collapse mechanism and the sensitivity of its specific energy absorption with respect to the thickness of the components is provided as well.