Static strength analysis and experimental research of clinched joints by two-stroke flattening clinching method

Clinching technologies are increasingly used to join sheet materials in manufacturing, especially in automotive lightweight applications. However, clinched joints have a weak static strength and high protuberance, which influence the application of the clinching technology. In order to improve the static strength and decrease the protuberance high of clinched joint, a new method to join aluminum alloy sheet materials with two-stroke flattening clinching (TFC) was investigated in this paper. The tension-shear strength, cross-tension strength, energy absorption, and failure modes of clinched joint and TFC joint were investigated. The stiffness (K) of the joints under different experimental tests was also studied. The results indicated that the mechanical behaviors of the joints were optimal when the forming force was 35 kN. The maximum cross-tension and tension-shear strength of TFC joint were increased by 514 N and 1145 N on average compared with the initial clinched joint. The main failure modes of the joints were the neck fracture mode under the tension-shearing and cross-tension test.