Reproducing the experimental pull-out and shear strength of clinched sheet metal connections using FEA

Clinching, commonly referred to as press-joining, is a mechanical joining technique which involves severe local plastic deformation of two or more sheet metal parts resulting in a permanent mechanical interlock or joint. This interlock is achieved by using simple tools like a die, a punch and a blank holder. Since no additional elements are used, the strength of the clinched connection is entirely determined by the clinch geometry, and, consequently, by the geometry of die and punch. As a result, for each combination of material and sheet thickness an optimal geometry of the tools can be derived. This can be done either through extensive experimental testing or, more cost-effectively, with the aid of numerical simulations. However, for these results to be useful they have to be able to reproduce the experimental strength of the connection. In this paper we investigate the possibility of predicting the shear and pull-out strength of a clinched sheet metal assembly using FEA. Numerical difficulties associated with these simulations and the preceding forming operation are discussed. A comparison between experimental data and simulation is provided.