Reserch On The Simulation And Optimization Of Self-Piercing Riveting Process For Dissimilar Materials

The trend of lightweight in automotive industry has become inevitable, and extensive use of aluminum alloy, high strength steel and the other advanced lightweight materials is one of the important means that can tackle this problem. Because of the huge physical difference between aluminum and steel and the formation of brittle metal intermetallic compounds, resistance spot welding process finds it hard to connect dissimilar materials like aluminum and steel.As a mechanical joining process without heat input, SPR process which has been utilized in connection of Aluminum body like Audi A8 is the most potential process to connect dissimilar materials like aluminum and steel. However, the research and application on dissimilar metal connection is still rare. There are a wide range of rivets and dies in gauge and material, the parameters of SPR process monopolized by companies like Henrob, Emhart and Bollhoff is determined by massive amounts of tests, which constrains the implication of the process.The research and application of the SPR process in China has just started. For specified combination, how to optimize process parameters fast by means of simulations with the aim of lower the cost is pressing. Based on the dissimilar material combination of AA6061-T6 and DP590, this article accomplishes simulations and optimization of the process parameters by means of DOE.1. FE Modeling of SPR process. Based on the process characteristics of SPR, this article models the simplified 2D axisymmetric FE geometry model by ANSYS/LS-DYNA, gets the sheets and rivets model parameters of isotropic and kinematic hardening plasticity by tests, sets the initial conditions and models the FE model. Then it gets verification by the comparison of the metallographic and simulation of the joints. In the end, it analyzes the dynamic process and stress contour.2. Effects of process parameters on joints formation. Based on the FE model, effects of length and hardness of rivets and diameter and convex of die on the joints formation are studied. The results show that the length of rivets is vital, hardness between 42 and 46 has little effect on the combination and the die with convex is a priority.3. Simulations and optimization of SPR process. The design of orthogonal experiment (DOE) method is used to study the optimal rivets and die parameters based on the model for the combination of 2mm AA6061-T6 and 1.2mm DP590. The results get verification by lap-shear tests and the feasibility of optimization of SPR process by DOE is verified, too. The optimal joint could be got by adopting rivet in 6.5mm and die in 9mm and convex in 0mm.