Finite Element Analysis And Optimization Of Front Impact Of Automobile Crash Box

As an important energy-absorbing device in a car bumper,an automotive energy-absorbing box is also an important component of passive safety of automobiles.It can effectively absorb collision kinetic energy when a car crashes at a low speed,thereby ensuring the safety of occupants and vehicles.When a car experiences a frontal low speed collision,it cannot achieve a 100% frontal collision due to various factors.Therefore,the nonlinear finite element LS-DYNA simulation software is used to simulate and analyze certain type of energy-absorbing box under the condition that the frontal low-speed collision occurs with the angle deviation.Car collision is a transient and complicated physical process,involving large deformation,large displacement and impact load.It is a nonlinear dynamic problem.Impact load and contact are dynamic contact problems in the process of car collision and affect the whole process of analysis.In this study,finite element software LS-DYNA was used to perform dynamic simulation analysis of the crash of the energy-absorbing box.The collision impact process was solved by the explicit dynamic calculation theory.The collision problem was solved using the center difference method discrete time domain.Using the explicit center difference method,the motion equations of the nodes can be solved without constructing the stiffness matrix,and convergence problems caused by nonlinear problems can be avoided.In this paper,a certain type of Crash box is selected and tested through a drop hammer impact test platform.The results of the crash simulation analysis of the LS-DYNA simulation software are compared to verify the feasibility of the LS-DYNA software simulation and the reliability of the simulation results.Then,taking into account the angle deviation of the frontal low-velocity collision of the car,several energy absorbing boxes of different sizes are proposed.Considering the frontal collision angle deviations occurring at 0°,10°,and 20°,the simulation of the collision is performed to ensure that the Crash box is on the front side.In the process of collision,it is able to absorb certain energy,and when the collision angle of the automobile is deviated,it can also make the energy-absorbing box have a good energy-absorbing effect and ensure the safety of the vehicle and the occupant.Through the optimization of the target optimization function and the simulation study,the optimal design of the energy-absorbing box is performed.The value of the energy absorption of the crash box and the change of the collision energy when the collision angle changes are obtained,and the best energy-absorbing performance is obtained.The design variables of the energy box,that is,the wall thickness of the energy absorber box is 3mm,length is 200 mm,and the number of sides is 6.Under this structure,the T value is the smallest when the collision angle is 0°,10°,and 20°.At the same time,taking into account the increase in the speed of automobile collisions,a new type of energy absorber box structure design is proposed,so that the Crash box can also exert a certain energy absorption effect in the event of a mid-high speed car collision to ensure the safety of vehicles and occupants.The research content of this article can provide certain reference value for the design of automobile manufacturers.