基于主S-N曲线法的T形接头疲劳评估和试验验证

以T形焊接接头为研究对象，将可能发生疲劳破坏的焊趾截面和焊喉截面的节点力转换为相对于中面焊线的等效节点力和弯矩，并利用平衡等效原理转化为线力和线弯矩，基于材料力学公式求出截面的结构应力，解决应力对网格尺寸敏感的难题。从焊缝疲劳破坏的机理出发，基于Paris断裂力学公式推导以等效结构应力为变量的一条主S-N曲线，评估焊缝的疲劳寿命。分析结果发现：采用主S-N曲线法评估的寿命与试验值最接近且破坏位置准确，该主S N曲线法准确性较高。

Fatigue evaluation and test verification of T-shape joint based on master S-N curve method

Taken T-shape weld joint as object, the nodal stresses of weld toe cross section and weld throat section where fatigue damage may occur are converted to the equivalent nodal stress and bending moment related to middle surface welding line, and it is converted to line stress and line bending moment. The section structure stress is obtained based on material mechanics formula. The problem that the stress is sensitive on the mesh size is solved. Based on the Paris fracture mechanics formula, the master S-N curve taking equivalent structural stress as variable is derived to evaluate the weld fatigue life. The analysis results show that the fatigue life evaluated using the master S-N curve is the closest to the test value and the failure location is accurate. The accuracy of the master S-N curve method is high.