Dynamics Numerical Simulation And Fatigue Analysis Of The SPR Joints

The self-piercing riveting(SPR) is a potential connection technology, especially for the connection of the light material(light alloy, composite material etc). SPR uses a punch forcing a semi-tubular rivet into the sheets, the rivet shank expansion and deformation like trumpet in the embedded process, forming a interlock between the two sheets or multilayer sheets, thus the upper sheet and the lower sheet connected together firmly. Though SPR is a new-type connection technique for sheets, the mechanical properties of it is better than the traditional spot welding. It known as the next generation connection technique is a key technology in the lightweight procedure of automobile, applied comprehensive in the auto industry.The molding process of the SPR used numerical method and experimental were approached in this paper. FEM software LS-DYNA based on Cowper-Symonds material model was used to built 2D model, and Lagrange method and r-self-adaptive mesh technique were used to simulate the whole shaping process of the riveting. The load displacement diagram of riveting experiment and the section of joint validated the rationality of the numerical simulation.This paper analyzed the influence of the parameter on shaping including the concave die and the convex platform, the dimension of the rivet, the static and dynamic friction coefficient, plastic strain ratio and so on, consequently making optimum design for the parameter of the riveting process better.The ANSYS software was used to investigate the mechanical property including statics analysis, dynamics analysis and fatigue analysis. Statics analysis obtained the maximum stress mainly distributed in the location where the two sheets contacted and closed to rivet hole, the upper sheet and the rivet head contacted and closed to rivet hole. From the modal analysis which extracted the first twenty-five mode shape, the odd shapes of the transverse vibration shown symmetry between the lap position for the two sheets, and the lap position located at the peak of shapes. It was explained that the lap position influenced the dynamic property of single lap-jointed SPR greatly, was the key location for fatigue analysis.The tensile shear experiments on specimens were made. Compared with 4 group data, the static tensile strength of the 2 series aluminum alloy SPR-adhesive bonded pieces were bigger than the 2 series aluminum alloy SPR pieces. The static tensile strength of the 2 series aluminum alloy SPR pieces were bigger than the 2 series aluminum alloy clinched pieces. The static tensile strength of the 5 series aluminum alloy SPR pieces exceeded 5000N. It provided enough preparatory work for the fatigue analysis of the joints in the future research.ANYSY/FE-SAFE was used to made fatigue analysis for SPR joints. From the fatigue performance analysis of the 5052 aluminum alloy single lap-jointed SPR found that fatigue damage existed in the location where the two sheet contacted and closed to rivet hole, the upper sheet and the rivet head contacted and closed to rivet hole. The FEM software ANSYS/LS-DYNA was used to simulate the whole crack propagation process of the riveting joint.The purpose of this paper was to realize the dynamics numerical simulation and fatigue analysis of the SPR joints, providing foundation for further research.