考虑残余应力影响的焊接结构疲劳总寿命预测方法  

A method for predicting the total fatigue life of welded joints considering residual stress

作　　者：管德清 丁湘泽 潘嫣然 GUAN De-qing;DING Xiang-ze;PAN Yan-ran(School of Civil Engineering,Changsha University of Science&Technology,Changsha 410114,China)

机构地区：[1]长沙理工大学土木工程学院,湖南长沙410114

出　　处：《长沙理工大学学报（自然科学版）》2020年第3期15-21,共7页Journal of Changsha University of Science and Technology:Natural Science

基　　金：国家自然科学基金资助项目(50578018);湖南省研究生科研创新项目(CX20190636)。

摘　　要：为了更加准确地评估焊接结构的疲劳寿命,提出了一种结合临界距离法和断裂力学理论的焊接结构疲劳总寿命预测方法。采用三维有限元动态模拟焊接过程,得到焊接残余应力分布规律,依据临界距离理论预测局部应力—寿命曲线,建立了疲劳裂纹萌生寿命的预测方法。在裂纹扩展阶段,按瞬态裂纹尺寸修正应力强度因子,利用权函数法求解残余应力强度因子,结合Forman公式计算疲劳裂纹扩展寿命。将焊接十字接头疲劳试验结果与预测总寿命进行对比分析,发现试验结果与预测值吻合较好。不同荷载水平下,裂纹萌生和扩展寿命各自所占总寿命比例不同,残余应力的存在对两阶段疲劳寿命均有不利影响。In order to evaluate the fatigue life of welded structure more accurately,a new method was presented to predict the total fatigue life,which combined critical distance method and fracture mechanics theory.The distribution law of welding residual stress was obtained through the 3D finite element dynamic simulation of welding process.The local stress-life curve was predicted by the critical distance theory,and the prediction method of fatigue crack initiation life was given.During the crack growth stage,the stress intensity factor of the crack was corrected according to the transient crack size,the residual stress intensity factor was solved by using the weight function method,and the fatigue crack propagation life was calculated by combining the Forman formula.Compared fatigue test results of welded cross joints with predicted total life,it is found that they are in good agreement.Under different load levels,with different proportion of crack initiation and propagation life to total fatigue life,the existence of residual stress all has an adverse effect on the fatigue life at both stages.

关 键 词：焊接结构 残余应力 疲劳总寿命 临界距离法 应力强度因子 权函数法 

分 类 号：TG405[金属学及工艺—焊接]