Fatigue Assessment of Welded Joints in AZ31B Magnesium Alloy by a Critical Plane Method

摘要:

通过有限元软件模拟横向十字接头的实际焊接过程，并进行温度场和应力场分析，采用基于Dang Van准则考虑焊接残余应力的临界面法对AZ31B镁合金典型角接头型式——横向十字接头进行了疲劳评定研究，并与疲劳试验结果进行对比分析。结果表明，法国焊接研究所提出的钢材参数及国内研究者提出的铝合金材料的参数均不适用于AZ31B镁合金横向十字接头，需要进行修正；经试验研究将参数修正为α*=0.5，β*=55 MPa，并拟合出相应的Dang Van图形，其结果与疲劳试验结果相吻合；说明修正后的临界面法可以对AZ31B镁合金横向十字接头进行合理的疲劳评定，而且依据应力集中大小，可以有效预测试件可能的疲劳断裂位置

Abstract:

The welding process of transverse cross joints was simulated by temperature field and welding residual stress fields in AZ31B magnesium alloy. On the basis of Dang Van criterion, considering the effect of welding residual stress, the critical plane method was used to assess the fatigue properties of the transverse cross joints in AZ31B magnesium alloy, and then the results were compared with the conventional fatigue test. The results show that the parameters for steel recommended by the French Welding Institute and for aluminum alloy recommended by investigators in china are all not suitable for AZ31B magnesium alloy which need to be amended as α*=0.5, and β*=55 MPa. Furthermore, the Dang Van curve is fitted and the result is consistent with the fatigue test, and the modified Dang Van criterion could assess the transverse cross joints in AZ31B magnesium alloy reasonably. According to the stress concentration, the possible failure position of specimens could be prognosticated