2023 Volume 41 Issue 1 Pages 26-35
In this paper, effect of arm length on tensile strength for resistance spot welded L-type joints was clarified based on comparing deformation of L-type joints with different arm length. 590 MPa grade cold-rolled steel (HT590) with a thickness of 1.6 mm was used. Tensile tests were conducted using L-type joints with six different arm lengths. FEM analysis was performed on specimens to simulate the experiments. To quantitatively evaluate specimen deformation, opening angle of specimen at failure was measured. Length from nugget edge to tensile axis, which is length of moment arm acting on nugget edge, was measured. The smaller arm length, the smaller opening angle. And, length from nugget edge to tensile axis became smaller. As a result, higher joint strength was obtained. Comparison of plastic strain in the vicinity of nugget showed that L-type joint with a small arm length had a narrower range of plastic deformation in direction of plate width at nugget edge. It was also confirmed that stress concentration at nugget edge was small. Therefore, high joint strength was obtained. It was found that strength of L-type joints is determined by opening angle and length from nugget edge to tensile axis. It was also clarified that a small range of plastic deformation in plate width direction at nugget edge reduces stress concentration at nugget edge as one of factors that improve joint strength of L-type joints.
