Crashworthiness Optimization Of Variable Strength Thin-walled Straight Beam

Passive safety is one of most important research points in the automobile industry. Automobiles are absorbing impact kinetic energy by the deformation of energy absorption device of car body during impact event. Therefore, passive safety is improved by enhancing the crashworthiness of energy absorption device. Widely used in the car body, the metallic thin-walled straight beam is a kind of effective energy absorption device. Crashworthiness optimization design of the metallic thin-walled straight beam is performed by improving structure and material that are two key factors that affect crashworthiness of the metallic thin-walled straight beam.Firstly, explicit finite element technique for numerical simulation is briefly introduced and the theory of design of experiment and surrogate model are summarized. Then, Crashworthiness of the thin-walled straight beam is optimized by using sectional variable strength sheets. The Latin hypercube design is performed with some parameters including the length of soft material and the yield strength of soft material and hard material, and then response surface surrogate model is established. The method of NSGA-? is adopted for multiobjective optimization with the optimization variables of energy absorption and initial peak force. The results indicate that the optimized thin-wall straight beam shows a great improvement of crashworthiness with increase in energy absorption and decrease in initial peak force.Thirdly, the topology optimization analysis is applied to augment the axial stiffness of the thin-walled straight beam. Based on the obtained results, a new type of the thin-walled straight beam is proposed by setting the central grooves axially on a pair of the side walls. To further enhance the crashworthiness of the new type of the thin-walled straight, size optimization is carried out. The results show that, the crashworthiness of the thin-walled straight beam is greatly enlarged after being optimized.Finally, sectional variable strength sheets are applied in the crashworthiness optimization design of the new-type thin-walled straight. According to the comparison of three optimization schemes, the variable intensity thin-walled straight shows the smallest initial force, and the variable intensity new-type thin-walled straight has the most total energy absorption.