Structural Design And Optimization Of Functionally Graded Energy Absorbing Box

Energy absorbing box is an important safety device in automobile body structure.It can absorb the kinetic energy of external impact by collapsing in an accident to ensure the safety of passengers.The traditional energy absorbing box structure cannot realize stable and orderly folding and collapse during the collision process,and has the disadvantages of poor energy absorbing effect per unit mass and per unit displacement,which limits the improvement of vehicle safety performance.It is an important research direction to select suitable materials to improve its energy absorption effect,control its collapse state and reduce its structural weight.The paper introduces a functionally graded energy absorbing box structure,that is,let the energy absorption box from one end of 316L stainless steel gradually transition to the other end of the aluminum alloy,to achieve in the energy absorption box weight reduction at the same time,to achieve good collapse state and energy absorption effect.Firstly,in order to find the optimal structure of the energy absorption box,the quasi-static and dynamic impact processes of the energy absorption box with different sections and different materials were simulated by finite element analysis software,and the collision force curve and deformation mode nephogram were obtained.At the same time,the bionic functionally graded energy absorbing box is manufactured by using the selective laser melting（SLM）technology,and compared with the finite element simulation model,the correctness of the simulation is verified.The quasi-static compression test was carried out on the universal testing machine,and it was verified that the functionally graded energy absorbing box with bionic section has the best energy absorption performance.Secondly,in order to improve the energy absorption effect of the energy absorption box,this paper proposes to optimize the cross section shape of the energy absorption box by using the structure design of the tibia section.Based on the optimized Latin hypercube experiment,the response surface model is designed,and the approximate model is constructed by the approximation theory.The more simple and more computable approximate function is used to solve the complicated objective function problem of the energy absorption box,and the specific structure of the cross section of the bionic energy absorption box is optimized by multi-objective.The simulation results show that the optimized bionic functionally graded energy absorbing box can realize stable folding and collapse from head to tail.Compared with the traditional energy absorption box,the bionic structure function gradient energy absorption box has improved the energy absorption effect per unit mass,and can effectively weaken the damage of the car body caused by collision.Furthermore,the optimal gradient distribution state of the energy absorption box material is studied.In this paper,the satisfaction function S is used to evaluate the improvement effect,and the gradient shape distribution factor P is optimized.At last,the forming process of aluminum alloy additive manufacturing is studied.By optimizing the scanning speed and laser power,combined with TiCN ceramic particle enhancement,the tensile strength,hardness,density and other properties of AlSi₁₀Mg material are effectively improved,and the forming process of parts is optimized.At the same time,the new TiCN enhanced AlSi₁₀Mg material was applied to the automobile energy absorbing box,and the influence of different process parameters and content on the microstructure and mechanical properties of the new material was studied,so that the performance of the new energy absorbing box was significantly improved.The test results show that 350w and 1650mm/s are the optimal manufacturing process parameters,and the 0.2%content is the optimal addition amount of TiCN.