Investigation of the underwater clinching process for joining metal sheets

Abstract

The underwater building of marine or offshore structures requires the application of underwater joining techniques. Compared to underwater welding and underwater adhesive bonding, clinching is energy efficient, clean, and simple to the tool. In particular, clinching is not susceptible to the effects of water as well as water depth. In the present study, the joinability of metal sheets by the underwater clinching process was investigated by experimental methods. Clinching tools with extensible die were used to join Al5052 sheets at different force levels. Material flow, shear strength, tensile strength, failure modes, and energy absorption were analyzed. The results showed that the application of clinching with an extensible die could be extended to underwater joining. In the study, three failure modes of the joints were obtained, including button separation, hybrid failure, and neck fracture. Increasing the forming force was effective in improving the strength of underwater clinched joints. 40 kN was considered to be the optimum forming force for joining double layers of Al5052 sheets using underwater clinching process.