中文摘要：

研究了双相钢焊点特征,对不同匹配双相钢搭接焊点进行了疲劳试验,获得了焊点的载荷寿命曲线。研究了双相钢焊点的疲劳裂纹扩展及失效形式,分析和解释了疲劳过程中的现象,并根据裂纹的实际扩展路径,提出了局部等效张开应力强度因子keq,从断裂力学的角度对双相钢焊点的疲劳失效进行了分析。结果表明,keq能够有效地关联具有不同厚度,不同熔核直径的搭接焊点试样的疲劳寿命,是反映双相钢焊点疲劳强度的有效参量,能够用来预测焊点疲劳寿命。

英文摘要：

Dual phase steel spot weld characteristic was investigated.And then fatigue strength of dual phase steel lap-shear spot weld was tested,the data for spot weld fatigue curve were obtained.The fatigue crack propagation path and failure modes of specimens were also studied.On the basis of crack propagation path local equivalent stress intensity factor keq was applied to analyze the fatigue life of dual phase steel spot weld.The test result indicated that keq was an effective parameter to predict spot weld fati...