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失效评定曲线(FAD)常用来评价焊接结构在出现裂纹后的安全性,为了验证这种曲线在评价焊接管结构在节点部位出现疲劳裂纹后安全性的适用性,采用实验测试和有限元分析的方法研究了3个含疲劳裂纹的T型管节点试件在静力作用下的极限承载能力及破坏过程。3个T型管节点试件首先进行疲劳实验在焊趾处产生表面裂纹,然后通过在支管端部施加轴向拉力作用检测节点的破坏过程。基于自行开发的含表面裂纹T型管节点的有限元网格自动产生程序以及ABAQUS分析软件,研究了在管节点破坏过程中表面裂纹最深点的应力强度因子大小,并通过实验的荷载-位移曲线确定了T节点试件的塑性极限承载力。在这些结果的基础上,验证了FAD在评价含疲劳裂纹的焊接管节点安全性方面的适用性。研究结果标明:FAD在评价含疲劳裂纹管节点的安全性方面是安全可靠的,但偏于保守。
The failure assessment curve (FAD) is often used to evaluate the safety of welded structures after cracks occur. In order to verify the applicability of this curve in evaluating the safety of welded pipe structures after fatigue cracks occur at the joint sites, the experimental test and finite element analysis Methods The ultimate bearing capacity and failure process of three T-joints with fatigue crack under static load were studied. The fatigue tests of the three T-shaped tubular joints first produced surface cracks at the weld toe, and then the failure process of the joints was detected by applying the axial tensile force at the ends of the branch. Based on the self-developed finite element mesh generator with cracked T-joint and the ABAQUS software, the stress intensity factor at the deepest point of the surface crack during the failure of the tube joint was studied. Through the experimental load-displacement curve Determine the ultimate bearing capacity of T specimen. Based on these results, the applicability of FAD in evaluating the safety of welded pipe joints with fatigue crack was verified. The results show that FAD is safe and reliable in evaluating the safety of fatigue cracked joints, but it is conservative.