Influence analysis of punch velocity on joint formation, binding mechanisms, and joint properties in clinching and self-piercing riveting

In mechanical joining, a wide variety of tool geometries and rivet types have been developed to meet different requirements. For example, this is due to the mechanical properties of sheet materials and the increasing number of material combinations that require joining. However, to address rising costs and sustainability demands or to react to supply chain disruptions, versatile joining processes are needed to reduce the amount of joining equipment required by adapting the process to the joining task. This study examines the influence of punch velocity on the clinching and semi-tubular self-piercing riveting processes, as well as on the binding mechanisms, joint's geometric parameters, and joint properties. The aim is to determine the relevant range of punch velocities based on material properties, such as strain rate dependence, and to assess whether punch velocity can be utilized as a control variable for versatile joining processes. To this aim, similar joints made of steel (HCT590X+Z), aluminum (EN AW-6014), and mixed joints of these materials are examined. The resulting joining forces are analyzed using force-displacement curves to evaluate the influence on the joining process. The form closure is examined using micrographs of the joints' geometric parameters. To characterize the force closure, the connection resistance is measured using the four-wire sensing method, and the load-bearing capacity is determined via a shear tensile test.