Improvement of joinability in a hole clinching process with aluminum alloy and carbon fiber reinforced plastic using a spring die

Hole clinching is a method for joining carbon fiber reinforced plastic (CFRP) and ductile materials. Previously, in conventional hole clinching, the joinability of CFRP and ductile materials was limited by the ductility of deformed materials, and damages to CFRP laminates. In this study, a new type of hole clinching tool called a spring die is proposed. This tool is designed to improve the joinability of materials in a hole clinching process using CFRP and aluminum alloy (AA5083). In spring die hole clinching, two pads supported by a coil spring are employed to improve the formability of ductile materials and to reduce damages to CFRP laminates by increasing the compressive hydrostatic stress during the hole clinching process. The effects of compressive hydrostatic stress on joinability in the hole clinching process were evaluated by FE-analysis and experiments. Finally, a single lap shear test was carried out to verify the applicability of hole clinching for joining CFRP and aluminum alloy.