Energy absorption capacity of composite structures in vehicular crash

This study investigates the crashworthiness of sinusoidal types of CFRP composite and DP780 steel crash boxes under the same impact conditions to compare their energy absorption capacities and evaluate their behaviours towards dynamic response, particularly focusing on acceleration values. A weight drop impact test was operated using a 305 kg impactor at a velocity of 7.67 m/s targeting crash boxes of the similar dimensions. Both experimental and numerical analyses were performed to provide a comprehensive evaluation. In order to simulate the numerical analyses more closely with the experimental values, the delamination effect in the composite material should also be considered. For this purpose, the delamination effect between the layers in the composite material was also taken into account by using the tiebreak contact type in LS-Dyna. In addition, since the trigger that will provide the initial damage in the composite crash box cannot be given geometrically as in metals due to higher initial peak load and the shock wave formed at the moment the weight first hits the crash box. Therefore, in order to measure the acceleration data correctly, a PVC foam was added on the composite crash box to absorb the shock wave by acting as a representative beam and in the next step, the simulations were completed in LS-DYNA using material cards MAT_024 for DP780 steel and MAT_054 for CFRP composite. The results showed that the CFRP composite crash box reinforced with the foam layer exhibited superior energy absorption capacity compared to DP780 steel. Moreover, the addition of the foam layer further improved the crash performance of the composite by reducing the effects of shock waves during impact, contributing to superior energy absorption and dynamic response. This study highlights the potential of CFRP composite as a lighter and more efficient alternative to metals in crashworthiness applications. In addition, the strong correlation between experimental and numerical results highlights the reliability of LS-DYNA in modelling crash behaviour, particularly in capturing acceleration characteristics, energy absorption mechanisms, and delamination effects of composite structures.