Design optimisation of composite bumper beam with variable cross-sections for automotive vehicle

Considering vehicle crash safety, gas emission and the improvement in the energy efficiency, carbon fiber reinforced plastic (CFRP) composite materials have been increasingly used in automotive applications. Bumper beam, as a main structural component of automobile bumper subsystem, is expected to protect occupants and its nearby components. It is an effective way to develop the bumper beam using CFRP to meet higher requirements of crash safety and lightweight. In this study, a stiffness degraded model is proposed to predict low-velocity impact behavior of CFRP bumper beam under two different loading conditions. Based on the simulation results, a novel design scheme of CFRP bumper beam with variable cross-sections is proposed to further improve material utilization. Finally, an optimization procedure incorporating the RBF modeling technique and NSGA-II algorithm was implemented to obtain the multi-objective optimal design. The results yielded from the optimization demonstrate that the optimized bumper beam with variable cross-sections is superior to its uniform counterpart in lightweight and crashworthiness and consequently is recommended as a better approach to replace the conventional metallic bumper beam.