焊接残余应力对对接接头疲劳裂纹扩展的影响  

Effects of welding residual stresses on fatigue crack growth behavior of butt joint

作　　者：顾颖 冯倩 任松波 孔超 古松[1] GU Ying;FENG Qian;REN Songbo;KONG Chao;GU Song(School of Civil Engineering and Architecture,Southwest University of Science and Technology,Mianyang 621010,China;Shock and Vibration of Engineering Materials and Structures Key Laboratory of Sichuan Province,Mianyang 621010,China)

机构地区：[1]西南科技大学土木工程与建筑学院,四川绵阳621010 [2]工程材料与结构冲击振动四川省重点实验室,四川绵阳621010

出　　处：《铁道科学与工程学报》2021年第10期2752-2760,共9页Journal of Railway Science and Engineering

基　　金：国家自然科学基金资助项目(51708467);工程材料与结构冲击振动四川省重点实验室开放基金资助项目(18kfgk13)。

摘　　要：为提供一种考虑焊接残余应力重分布效应的疲劳裂纹扩展数值模拟方法,并以此研究焊接残余应力对对接接头疲劳裂纹扩展的影响,采用热弹塑性有限元法计算焊接残余应力,再基于计算机图形学与等参元逆变换提出应力映射技术,并借助该技术将计算的应力映射到疲劳裂纹扩展分析模型。采用NASGRO方程,考虑焊接残余应力的重分布效应,研究焊接残余应力对疲劳寿命的影响。研究结果表明:1)即使是很小的焊接残余拉应力也可能对材料疲劳寿命造成显著的降低。相反,很小的焊接残余压应力也可能显著地提高材料的疲劳寿命,本算例不到10%材料屈服强度的焊接残余拉/压应力,将疲劳寿命降低了/提高了25%/75%以上;2)焊接残余拉应力对疲劳寿命的影响随着应力的增大而增大,但增大的比例随着应力值的增大而显著减小;3)残余压应力对疲劳寿命的影响程度要比同值的拉应力影响大。此外,根据研究结果还给出了一些降低焊接残余应力不利影响及提高材料疲劳性能的工程建议。This paper aimed to present a numerical simulation method of fatigue crack growth considering the redistribution effects of welding residual stresses(WRSs),and to investigate the influences of WRSs on fatigue crack growth behavior of butt joints based on the proposed method.The WRSs in a butt joint were calculated by thermal elastic-plastic finite element method(FEM).The stress mapping technology was subsequently developed based on computer graphics and inverse-conversion algorithm of isoparametric element.By using the proposed technology,the calculated WRSs were mapped into the model for fatigue crack growth analysis.Finally,with the redistribution effects of WRSs considered,the effects of WRSs on the fatigue life were investigated based on NASGRO equation.The results show that:(1)even a small tensile WRS can result in a significant decrease in fatigue life;on the contrary,a small compressive WRS may greatly improve the fatigue behavior.In the case studied,a tensile/compressive WRS with a magnitude of less than 10%of yield strength can reduce/increase the fatigue life by more than 25%/75%;(2)the influences of tensile WRS on fatigue life increase as the magnitude of WRS increases;however,the extent of increase reduces significantly as the magnitude increases;(3)the effects of compressive WRS on fatigue life are greater than those of tensile WRS with the same magnitude;additionally,some engineering proposals were provided to reduce the adverse effects of WRSs or improve the fatigue performances of materials.

关 键 词：焊接残余应力 疲劳裂纹扩展 热弹塑性有限元法 线弹性断裂力学 NASGRO方程 

分 类 号：U441.4[建筑科学—桥梁与隧道工程]