Development of composite double-hat energy absorber device subjected to traverser loads

This paper introduces a new carbon fiber reinforced plastic (CFRP) structural system in the field of crashworthiness. CFRP hat-shaped and angle-shaped stiffeners were used to develop a double-hat collapsible energy absorption system. Three different design alternatives were investigated. The first alternative is an open-cell design (OC) consisting of two flipped hat stiffeners with four right angles on the edges. The second alternative is a one-in-cell double-hat design (1C), consisting of OC design with additional one inside small hat stiffeners edged with angles. The third alternative is a two-in-cell double-hat design (2C), consisting of OC design with additional two inside small hat stiffeners edged with angles. Three modes of failure were observed, classified as local buckling (mode I), top wall bending (mode II), and brittle collapse that resulted from Euler buckling (mode III). The crashworthiness characteristics were evaluated for the three designs. The 2C double-hat design showed the highest peak load and specific energy absorption (SEA). Accordingly, the core of the 2C design was filled with foam to increase the energy absorption capability and enhance the structure's stability. Results showed that the SEA of the 2C + foam design was increased by more than 50% compared to the coreless 2C double-hat design.