Experimental and Numerical Investigation of Energy Absorption Characteristics of a E-Glass/Epoxy Crash Box

Abstract

Crash boxes are energy absorbing components generally placed at the front end of cars to reduce the amount of damage at especially low impact velocities. The number of electric vehicles has been increasing recently, so weight reduction studies are. For this reason, lighter glass or carbon fiber reinforced composite crash boxes are preferred instead of steel ones. In the current study, the dynamic compression behavior of a rectangular cross-section thin-walled composite crash box was investigated both experimentally and numerically. The main aim of the study was to understand the effective damage modes and monitor the deformation sequence experimentally and numerically. Once the numerical model is verified then it can be further used to reveal the behavior at different impact velocities and geometries. The methodology followed in the study first started with the static mechanical characterization of the composite material. Within the scope of this study, 2×2 twill-woven glass fiber/epoxy crash boxes were produced using the vacuum bagging method. Quasi-static compression and tension tests were carried out in accordance with ASTM D3039 and ASTM D6641 standards. In the numerical part, Radioss finite element package was used with the material model of MAT 25 along with the failure option of Tsai-Wu. Experimental dynamic crushing tests of the crash box was carried out using a custom made drop-weight tester at impact velocity of 4.4 m/s and dropping mass with 450 kg. The material model constants were obtained once the coupon based static and dynamic tests were completed. From the dynamic crushing tests, maximum and mean force values of 225 and 65.0 kN were noted, respectively. There is close agreement between the experimental and numerical results both in terms of force and displacement values. This verified numerical model can further be used to investigate the crushing characteristics at different impact conditions.