焊接残余应力对Y型相贯节点极限承载力影响分析

采用ANSYS的热 结构间接耦合、生死单元技术模拟Y型相贯节点的焊接过程；将牛顿-拉普森法和弧长法结合，求解Y型相贯节点极限承载力，给出求解流程；分析支管外径与主管外径比、支管倾角、主管径厚比等几何参数对Y型相贯节点极限承载力的影响，将考虑和不考虑焊接残余应力的计算结果进行对比分析。研究结果表明:焊接残余应力降低了Y型相贯节点的极限承载力；支管外径与主管外径比β越大，主管的径厚比γ越小，支管倾角θ越小，则Y型相贯节点极限承载力降低越多；结构设计时，保证强度和安全的前提下选择合适的支管外径、主管壁厚和支管倾角，可减小焊接残余应力对Y型相贯节点极限承载力的影响。

Analysis on Influence of Welding Residual Stress on Ultimate Bearing Capacity of Y-joints

The welding process of Y-joint was simulated by using thermal structure indirect coupling and birth-death element in ANSYS. Combined Newton-Raphson method and arc-length method, the ultimate bearing capacity of Y-joints was solved, and solution flow was given. The influence of geometric parameters such as the ratio of diameter of branch pipe and diameter of pipe, angle of branch pipe, ratio of diameter and thickness of pipe, on the ultimate bearing capacity of Y-joints with considering welding residual stress was analyzed. Ultimate bearing capacities of Y-joints with welding residual stresses and without welding residual stresses were compared and analyzed. The results show that the ultimate bearing capacity of Y joint is reduced by welding residual stress; because values of the βare larger, or values of the γ are smaller, or values of the θare smaller, the ultimate bearing capacity of Y-joint is more reduced. In structural design, to ensure the strength and safety of structure, choosing the suitable diameter and angle of branch pipe, wall thickness of pipe, the effect of welding residual stress on ultimate bearing capacity of Y-joint can be reduced.