Parallelized optimization design of bumper systems under multiple low-speed impact loads

Abstract

Majority of existing design optimization of bumper systems has focused on one single impact loading case in literature, which may not offer proper performance under other loading cases. This study aims to address this issue by developing a multiobjective optimization approach, in which multiple impact loading scenarios are considered to optimize the intrusion and energy absorption of the bumper system. Modeling of real-life impact scenarios is first validated by comparing the numerical results with the experimental data. Based upon the Latin hypercube design (LHD) and Kriging surrogate approaches, energy absorption (EA) and maximum intrusion (MI) are formulated in terms of design variables to consider the structural crashworthiness and repair/maintenance cost, respectively. In order to generate Pareto solution in the multiobjective optimization effectively, the recently developed Kriging Believer based parallelized efficient global optimization (EGO) algorithm is adopted to optimize the bumper system subject to three impact loads, namely the low-speed sled crash, dynamic three-point bending and 40% offset impact, respectively. These different load cases are considered through a weighted average scheme. The optimization results indicate that the Pareto solutions largely depend on the assignment of weight factors to different load cases. In order to generate more reasonable results, the National Automotive Sampling System-Crashworthiness Data System (NASS-CDS) database is also used to determine the weighting factors for each loading case. It is found that for the intrusion objective, the design under the multiple impact loads offers an intrusion reduction of 20.27% in the sled crash, 5.84% in the 40% offset impact, in comparison with the baseline design. The intrusion of three-point bending is the same as that of baseline design to compromise other more frequently occurring load cases. For the energy absorption objective, although the design leads to increase in EA by 3.01% in the sled crash and 1.79% in 40%-offset impact, the performance in the three-point bending is actually sacrificed to compromise the other more frequently occurring load cases. The study help gain insights into the design optimization of a bumper system for real-life automotive engineering.