Study on Measures against Spot Weld Fracture of Ultra-High-Strength Steel Frame (Second Report)

- Investigation of Appropriate Joining Process and Location Based on Loaded Condition of Spot Weld Zone -

Abstract

Loaded condition of spot weld zone was investigated by CAE when ultra-high-strength steel frames had high-speed 3 point bending deformation or torsional deformation to find some reasons of spot weld fracture of the frames. The result showed the condition depended on the deformed conditon. Additionaly, some appropriate joing methods were proposed to avoid the spot weld fracture based on the result. Concretely, under bending deformation mode, the method is expansion of the joining area at bending area and continuous joing such as line laser or short pitched spot weld around the bending area, under torsional deformation, both the expansion and continuous joing were useful. The validation of the proposal was confirmed by CAE and experiment of high-speed 3 point bending test and torsional test.