Shape optimization of bumper beam under low-velocity impact

Abstract

Bumper beam is an important part of vehicles providing protection from colli sions. Its main function is to prevent damage to the rest of the vehicle in low-speed collisions. For this reason, it should absorb the energy of collision at low speeds without undergoing large deflections and large plastic deformation. Weight, cost, and perfor mance are important factors in the design of automotive parts. The objective of this study is to obtain an optimum shape that improves the performance of a bumper beam without increasing weight. The impact phenomenon is simulated in ANSYS LS-DYNA according to IIHS low-velocity impact standard, in which the full-width of the bumper beam hits a rigid barrier by 10 km/h. The objective function to be minimized includes the maximum intrusion as well as the weight. The cross-sectional profile is defined by spline curves passing through key points. The coordinates of the key points are chosen as the optimization variables. The bumper beam is optimized for a steel and an aluminum. Different optimum shapes are obtained for different materials. The two optimum designs and some benchmark shapes are compared in terms of maximum in trusion of the bumper beam, peak transmitted force, maximum plastic strain, weight, and cost. Significant improvements are observed in the performance of the optimally shaped beams compared to the benchmark beams.