Influence of plane mixed-mode loading on the kinking angle of clinchable metal sheets

Abstract

The aim of the present paper is to investigate the influence of plane mixed-mode loading on the kinking angle of clinchable metal sheets. In many fields of product manufacturing, the structures consist of individual components and sheets. The sheets can be joined to form complex structures with the aid of the simple and auxiliary part-free joining process "clinching". The main area of application are sheet metals with a maximum total thickness of 4 mm. During operation, joined structures can experience multi-axial, out-of-phase mixed-mode loading, causing small defects or cracks to propagate through the structure and ultimately lead to the component failure. Beginning with investigations of the influence of plane mixed-mode loading on the kinking angle of clinchable metal sheets, CTS specimens are taken from the 1.5 mm thick metal sheets of the base material used in the clinching process. In these specimens a pre-crack is initiated by Mode I loading. Subsequently, the specimens are clamped at different loading angles with the help of a special loading device, which enables a superposition of normal and shear loading. Under different loading angles, the specimens are subjected to cyclic loading to cause a kinking of the crack path. The resulting kinking angle is measured and compared with an analytical criterion for determining the kinking angle. Furthermore, the criterion is verified with the help of numerical crack growth simulation.