Effect Of The Self-piercing Riveting Situation Of Dissimilar Metal On Fatigue

With the development of automotive industry,automotive light-weighting has become more and more important in automotive industry's development.It is difficult to connect dissimilar lightweight metals by welding process.Self-piercing riveting(SPR)process with semi-tubular rivet not only avoid these disadvantages but also owns many advantages,such as no noise,no pollution,and so on.It has very excellent development prospects and application prospects.Taking AL5052 aluminum alloy sheets and Q235 steel sheets for research objects,this paper studied the effect of riveting position on static strength and fatigue property for shear structures with two semi-tubular rivets through experiments and simulation.In order to establish foundation for the later experiments and simulation,the article made a brief analysis for fatigue failure mechanism of self riveted joints,explained the whole process of fatigue crack for self riveted joints from initiation to propagation to breaking,pointed out places causes of possible fatigue crack,introduced fatigue fracture appearance from macroscopic and microscopic and provided several fatigue analysis method.Simulation of static test process was conducted in ABAQUS finite element software by changing the number of rivets.We can more directly understand the failure forms and process through comparatively analyzing load peak value and the distribution of stress and strain.Compared the quasi static tensile results of simulation with experiment results,then providing the effective structure for fatigue simulation.Riveting tests of AL5052 aluminum alloy sheets and Q235 steel sheets were done by SPR technology,and cross-section forming quality of SPR was evaluated through intuitive method and profile measuring method.Influences of different parameters(lap joint size plates,orientation arrangement of rivets,the vertical distance from the central of rivets to the boundary of sheets,and so on)on strength property and fatigue property of lap-shear specimen with two rivets were analyzed.Searched on the arrangement law of specimen on mechanical property and observed the fatigue fracture using the SEM.Calculated fatigue life of each specimen with two rivets in transverse arrangement through FEMFAT software corresponding to experiment schemes.Compared the simulation results with experiment results,it shows that when rivets were arranged in transverse direction,fatigue property of specimen will decrease if the vertical distance from the central of rivets to the length of sheets is too big or too small.Within limits,fatigue life increased as lap joint size plates increased,and then it decreased.Errors existed between simulation results and experiment results.Simulation results always be lower than experiment results and controlled in one order of magnitude.The arrangement law of specimen on fatigue life which simulationgot is agreement with the experiment.