抵抗スポット溶接継手の接合強度に及ぼす溶接部形状の影響に関する数値解析的検討

抄録

Recently, high-strength steel sheets have been used to automotive structural components to reduce the body weight and improve the passive safety. Resistance spot welding is used as method in jointing steel sheets. However, there is a problem that cross tension strength which is an index of the joint strength decreases with improving the base metal strength. Therefore, to solve the problem, it is effort to make the weld characteristics control and improve the joint strength. However, there are few researches of shape factors considered. In this study, focusing on the weld shape, the effects of weld shape on the joint strength of resistance spot welded high-strength steel sheets were investigated by experiment and numerical analysis. First, to investigate whether the weld shape effects the joint strength, cross tension test was carried out on joint which changed weld shape. As the result, the strength was improved by changing the weld shape. Base on this experimental result, the effects of the weld shape on the stress and strain distribution was investigated by numerical analysis. As the result, the stress of thickness direction at the vicinity of the edge of nugget and the stress intensity factor decreased by changing weld shape. It is considered that these decreases are caused by changing the weld shape and increasing the amount of deformation of weld joint. From the above, it became clear that by changing the weld shape of the resistance spot welded joint, the deformability increases, and the joint strength improves.