Analytical method to predict the pull-out strength of clinched connections

Clinching is a mechanical joining technique by which sheet metal parts can be assembled without the use of additional material inserts. The strength of such a connection highly depends on the final geometry of the permanent joint. The assessment of the mechanical strength is conventionally done by conducting simple experiments such as a single shear lap test. However, it is generally recognized that the axial strength of this type of connections is considerably lower than its strength in shear loading. As a consequence, it is clear that applications where the joint is loaded in the axial direction should be handled carefully. The so-called pull-out strength can be investigated by dedicated experiments or sophisticated finite element calculations. In this paper an analytical approach to estimate the pull-out strength is presented. The first part describes the method along with the necessary assumptions. The remainder of this contribution validates this analytical method through a new experimental setup and a finite element model. In addition, a correction curve is derived which enables to adapt the analytical solution accounting for bending effects. Finally, the alternative method is applied to a joint connecting two DC05 sheets.