【摘要】 综合考虑熔核尺寸、工件翘曲变形、电极压痕等因素建立了三维弹塑性有限元模型,分析了镁合金电阻点焊接头的应力、应变场分布特点,以揭示焊点断裂产生的原因。结果显示,由于电阻点焊接头在受力时熔核是主要的承载部位,在熔核边缘与板缝结合处由于几何非线性和材料的非线性将出现应力集中,这是点焊接头受力时最薄弱的环节,裂纹从这里萌生,沿熔核边缘高应力区扩展。镁合金点焊接头断裂均为沿焊点熔核的纽扣形撕裂,断裂属于韧性断裂。更多还原

【Abstract】 A three-dimensional elastoplastic finite element model,taking account of nugget size,workpiece deformation and electrode indentation,was developed for stress/strain analysis of welding joint in resistance spot welding of Mg alloy in order to study the failure behavior of weld.The results show that the weld nugget is the main load-bearing part,and the stresses concentration appears at the interception of the spot-weld nugget boundary with the workpieces interface due to abrupt geometrical discontinuity and material discontinuity,where the crack is more easily initiated.The crack extended in the high stress region along the boundary of the nugget.Fracture analysis results show the characteristic of Mg spot-weld fracture is fastener tear and belongs to the ductile fracture.更多还原