Optimization Of Crash Box And Frontal Longitudinal Beam Based On The Blanks With Tailored Thickness

Lightweight design and passive safety are two main research areas in the automobile industry. The safety of the car should be remained or improved when the car is lighter. The lighter design of a car’s crash box and the frontal longitudinal beam, which are two main passive safety components, should meet the demands of safety. In this paper, two new lightening techniques, namely tailor rolled blank (TRB) and tailor welded blank (TWB), are used for making the crash box and the front longitudinal beam.Firstly, the performance of a car’s crash box whose thickness is uniformly changed is researched based on the RCAR regulations, and the paper verifies the accuracy of the finite element model. The simulation also shows the deformation rule of the crash box.Then, a crushing experiment is conducted, showing the TRB can induce an ideal crushing performance. From this result, this paper introduces an innovation, that is to replace the induction slot with blank which is non-uniform. Based on this method, the finite element model of TRB crash box is constructed. The mass, the peak force, the energy absorption and the efficiency of energy absorption are regarded as the optimization variables, and then the structure of the crash box is optimized designed. The research shows that, the crash performance of the crash box is greatly enhanced after being optimized.Thirdly, the optimization of the crash performance of the front longitudinal beam is researched. TRB are used in design the new kind of the front longitudinal beam. The specific energy absorption (SEA), the peak force and the mass of the beam are regarded as the optimization variables, and the experiment design method, the Kriging surrogate model and NSGA-II are used for multiobjective optimization. After multiobjective optimization, the lighter longitudinal beam shows lower peak force and higher capacity of absorbing energy.Finally, TWB is applied in designing the front longitudinal beam, and the thickness of each part of TWB is ideally designed. The comparison of the results of TWB, TRB1 and TRB2 shows that, the TWB tube has a greater capacity of absorbing energy, while the TRB2 tube has lighter mass as well as the smallest peak force.