等效热点应力法结合临界面法评估焊接接头多轴疲劳强度研究

Multi-axial Fatigue Strength Assessment of Welded Joints Based on Equivalent Hot Spot Stress Approach and Critical Plane Method

基于焊缝本身引起的非线性分布应力自平衡的性质,在板厚方向应力峰值零点位置定义等效热点应力,结合基于临界面法的MWCM法建立评估复杂焊接接头多轴疲劳强度的方法。采用数值计算分析零点位置的变化规律,建立零点位置拟合方程。利用公开发表的试验数据以及现有的热点应力法有限元计算结果对等效热点应力法进行精度验证。结果表明,等效热点应力法和现有的热点应力法具有很好的一致性,能在一定程度上考虑厚度效应对疲劳强度的影响,可以评估多轴疲劳强度。

Based on the self-equilibrium feature of nonlinear distribution stress in welding , the equivalent hot spot stress can be defined at a point （ called zero point ） in plate thickness direction where nonlinear distribution stress due to the notch effect of the weld is equal to zero .With the combination of MWCM （ Modified W？hler Curves Method ） based on principle of critical plane, a new approach for the multi-axial fatigue strength assessment of complex welded joints is proposed .The change trend of zero point is investigated by numerical calculation to get a fitting equation for determining the zero point position .The published fatigue tests data and numerical stress results of some welded joints are used for accuracy verification of the proposed equivalent hot spot stress approach .The equivalent hot spot stress approach is verified to be consistent with the current hot spot stress ap -proach and also have higher accuracy for being able to consider the thickness effect on the fatigue strength to a certain extent .It can be used to estimate the multi-axial fatigue strength of welded joints .