Crashworthiness Analysis Of SPR Joint In Dissimilar Metal Vehicle Body Structure

With the increasing emphasis on lightweight vehicle,new lightweight materials continue to be used in vehicle body structure design.In order to solve the problem of dissimilar metal connection,the study of SPR(Self-piercing Riveting)had been paid more and more attention.As the existing SPR joint finite element model was complex,the number of elements was large,the calculation efficiency was low,which limited the simulation analysis of SPR riveting body structure.In order to improve the design efficiency of dissimilar metal vehicle body structure,it is urgent to establish a simplified model of SPR joint for dissimilar metal connection.Based on the dynamic tensile test of dissimilar metal single-lap specimen and coach-peel specimen connected by SPR,this thesis explored the modeling method of simplified model of SPR joint.By comparing the load-displacement curve and the final deformation of the specimens,the accuracy of the modeling method and failure criterion of SPR joint was verified under the single test condition of single rivet.And more physical information such as the force situation of joint,the stress and strain of the panel,which were difficult to get in the test,were obtained from the simulation results.The deformation process of the single-lap specimen and the coach-peel specimen under the impact load was analysed.The characteristic of SPR ductility failure was simulated by detailing failure criterion of joint.Then,the modeling method of simplified model for joint was applied to collision simulation of front rail,which was typical energy absorbing vehicle body structure.Based on the axial impact test of dissimilar metal front rail riveted by SPR,the accuracy of front rail model was verified under the complex condition of multiple rivets through comparing the load-displacement curve and the deformation of the front rail.And summarized the deformation mode and energy absorption process from the simulation results.Finally,the SPR riveted dissimilar metal front rail under axial impact load is taken as the research object.According to the position of the derivational groove,all rivets were divided into two parts,front and rear parts.The effects of different rivet spacing on the deformation mode and energy absorption of front rail were studied.It is found that,in a certain range,the smaller the rivet spacing in front part,the greater the initial peak force.But the rivet spacing in front part had little effect on the integral deformation mode and energy absorption.While the rivet spacing in rear part had little effect on the initial peak force.And the influence of the rivet spacing in rear part to the force-transfer characteristic,energy absorption characteristics and deformation modes in collision early stage could be ignored.But the effect of rivet spacing in rear part on crashworthiness evaluation indexes,such as deformation,energy absorption and average impact force,was large.Even the different rivet spacing in rear part resulted in different deformation mode at the end of collision.