Multilayered Aluminum Clinch Joints: An Experimental and Numerical Investigation of the Manufacturing Process

The classical clinch joints are two-layered spot joints; however, several different variants have been developed so far. Although, the technology is capable to join more than two sheets. In this study, aluminium spot joints were produced and examined because in the past few decades, the importance of aluminium sheets is increasing in car body manufacturing due to their low weight and relatively high strength. The aim of this study is to investigate the multilayered aluminium clinched connections from the point of view of forming process, and resultant parameters. Experimental and numerical studies were performed to analyze the process itself and analyze the resultant joint geometrical values which are primarily indicators of the joint strength. In this study, the applied material was EN AW-5754 aluminium alloy, and the total connected thickness of sheets was 2 mm. The joints were manufactured by a TOX clinching tool at the University of Miskolc. The most important parameters of the joints from a mechanical strength point of view are the neck thickness and the undercut, besides the only measurable parameter, the residual bottom thickness, which were analyzed. The cross-sections of the clinched joints were analyzed by microscopical investigations. The joints, and basically the joining by forming process were also analyzed numerically by 2D asymmetrical finite element model to virtually analyze the forming load, material flow inside the clinching tool and analyze the stress and strain state of the joints.