Investigation of mechanical behavior of the reshaped joints realized with different reshaping forces

• The protrusion height of the clinched joint was observably reduced.
• The strength of the joint can be increased by the reshaping method.
• Neck fracture mode is the main failure mode for almost all the joints.
• The reshaped joint can absorb more energy in the failure process.
• The reshaping method was proved to be effective and reliable.

In recent years, mechanical clinching has drawn more and more attentions in the field of thin-walled structures. However, the exterior protrusion on the joint may restrict the use of this joining technology in the visible areas. A reshaping method was investigated to reduce the protrusion height in this paper. The protrusion was compressed by a pair of flat dies in the reshaping process. The neck thicknesses, interlocks, bottom thicknesses, protrusion heights and diameters of the reshaped joints with different reshaping forces were gotten to show the material flow of the joints. All the neck thickness and interlock were enlarged with the decrease of the protrusion height. When the reshaping force was set to 30 kN, the protrusion height was reduced from 1.69 to 0.38 mm. The average cross-tensile strength was increased from 986.5 to 1133.8 N, and the average tension-shearing strength was increased from 1536.4 to 2285.9 N. Neck fracture mode was the main failure mode in the strength tests. The cross-tensile strength, tension-shearing strength and energy absorption of the reshaped joints are all higher than those of the clinched joint. The reshaping method was proved to be reliable and effective.