考虑残余应力的焊接节点疲劳寿命有限元分析

为研究残余应力对焊接结构疲劳性能的影响,基于热力耦合计算方法建立了热弹塑性有限元模型,模拟T型节点焊接全过程及焊后热处理的温度场与应力场.基于扩展有限元法建立T型焊接节点断裂力学数值模型,将焊接应力场作为初始条件引入模型并分析其对疲劳裂纹动态扩展行为的影响.结果 表明,未考虑残余应力时,焊接节点疲劳裂纹向焊缝两端均匀发...

Finite element analysis of fatigue life of welded joint considering residual stress

In order to study the influence of residual stress on the fatigue performance of welded structures, a thermo-elastoplastic finite element (FE) model was established via thermal coupling method to simulate the temperature field and stress field during both the whole T-joint welding process and the post-welding heat treatment process. Based on the extended FE method, the numerical model of fracture mechanics of T-shaped welding joints was established. The initial condition of welding stress field was introduced into the model and its influence on the dynamic propagation behavior of fatigue cracks was analyzed. The results show that when residual stress is not taken into account, the fatigue crack of welding joint develops uniformly at both ends of the welding seam, and the crack propagation pattern is not consistent with the experiment. Post-welding heat treatment can significantly reduce the high tensile stress and compression stress generated by welding, but the increase of fatigue life span is less significant, at only 6.1%; considering the residual stress, the fatigue crack growth path is more consistent with the experiment. The influence of welding residual stress on the fatigue crack growth path should be considered in FE simulation of welded structure.