Improvements in numerical simulation of the SPR process using a thermo-mechanical finite element analysis

Self-piercing riveting (SPR) has been widely used over recent years in the automotive industry to join lightweight aluminium structures. However, the extensive experimental trials needed to assess the feasible rivet/die combinations within a body in white assembly facility present a serious constraint for the application of this process on a large manufacturing scale. Therefore, having a virtual tool able to assess or predict the feasibility of a rivet/die combination is of primary importance for the automotive industry. In this study, a 2D axisymmetric model based on thermo-mechanical finite element analysis (FEA) was proposed to simulate the SPR process using material data determined at a strain rate of 1 s−1 and temperatures ranging from ambient to 300 °C. The increase in temperature due to friction and plastic deformation was numerically investigated using simufact.forming™ software. The effects of thermal softening and strain hardening at different strain rates were characterized for the substrate material (aluminium alloy AA5754) and their influence on the numerical simulation assessed. Accounting for these parameters led to a significantly higher level of correlation between simulation and experimental results for a number of different SPR joint configurations representative of industrial applications.