Deformation behavior of high-strength steel rivets for self-piercing riveting applications

Abstract

In this study, the deformation behavior of self-piercing rivets made of high-strength steel was experimentally and numerically investigated. In order to produce samples for compression testing both the head and the tip of each rivet were cut off. The remaining hollow cylinders, i.e. the shafts of the rivets, were then compressed with different jaw speeds using a Gleeble 3800 testing machine. Based on the test results the flow curves of the rivet material were determined for different strain rates. The final geometries of the deformed samples were captured using a GOM ATOS III Triple Scan measurement system. Compression testing was modeled using the finite element software Simufact FormingTM. The numerical results were validated against the experimental results using the force-displacement curves as well as the shapes of the deformed samples. Thus, the process parameters (e.g. the friction coefficient) and the material properties (e.g. the flow curve) were varied until the shapes of the deformed samples in both the simulation and the experiment were almost identical. Good agreement between the rivet shapes and between the force-displacement curves indicated the obtained flow curve to describe properly the deformation behavior of the self-piercing rivets.