Crashworthiness Analysis Of Heterogeneous Metal Automobile Front Rail

With the continuous application of lightweight materials in automobile manufacturing,itposes a huge challenge to the traditional vehicle body connection process.In order to solve the dilemma of heterogeneous metal connection process,SPR(Self-piercing Riveting)process as a new type of cold stamping connection process for connecting heterogeneous metal vehicle body structures has gradually been paid attention by researchers.Because the residual stress and strain distribution of the joint,material plasticity and failure of the joint must be considered during the modeling of the finite element detailed model of the SPR joint,the mechanical properties of the SPR joint can be accurately simulated,but it will also cause the calculation efficiency of the detailed model to be low.Therefore,it is severely restricted to systematically study the mechanical properties of SPR joints.First,based on the CONSTAINED_SPR2 constraint model,three typical working conditions of the U-shaped test and peeling tests were simulated.In the simulation process,by adjusting the initial parameters of the CONSTAINED_SPR2 constrained element and observing the mechanical characteristics and failure modes of the CONSTAINED_SPR2constrained element under different conditions,a complete force-displacement curve from the initial deformation to the joint failure was established.The conclusion that the simulation results are consistent with the test results is obtained,and the accuracy of the CONSTAINED_SPR2 constrained element as the rivet equivalent unit is verified,which provides a solid foundation for the subsequent automobile front rail crash simulation.Secondly,the CONSTAINED_SPR2 constraint element is applied to the simulation of the axial high-speed impact test of the heterogeneous metal front rail.The accuracy of the application of the CONSTAINED_SPR2 constraint element to the impact simulation of the front rail is verified by benchmarking the force-displacement curve,initial peak force,deformation mode,total energy absorption and other impact crashworthiness indexes of front rail test and simulation.Based on the finite element model of the front rail of the equivalent unit of the SPR joint,the different flange width,distance of riveting to flange edge and the rivet spacing of finite element model of the front rail are simulated separately.By analyzing the crashworthiness indexes such as specific energy absorption,initial peak force and deformation mode,the optimal front rail structural parameters are obtained,and the crashworthiness performance of the heterogeneous metal front rail is improved.Finally,the traditional steel front rail and steel-aluminum heterogeneous metal front rail are used in the vehicle frontal crash simulation.By comparing the energy absorption and deformation mode of the two crashworthiness indicators,it is proved that the heterogeneous metal front tail is superior to the traditional steel front rail in terms of crash energy absorption and lightweight.It has laid a research foundation for the lightweight design of vehicle.