反应堆压力容器J形坡口焊接接头区控制棒驱动机构管座裂纹的应力强度因子  

Stress Intensity Factor for Cracks in Control Rod Drive Mechanism Nozzles near the J-weld in Reactor Pressure Vessel Head

作　　者：顾正军[1] 王国珍[1] 轩福贞[1] 涂善东[1] 刘长军[1] 

机构地区：[1]华东理工大学承压系统与安全教育部重点实验室,上海200237

出　　处：《机械工程学报》2011年第20期109-115,共7页Journal of Mechanical Engineering

基　　金：国家高技术研究发展计划(863计划;2009AA04Z409;2009AA04Z421);国家自然科学基金(51075149)资助项目

摘　　要：利用热弹塑性有限元法计算研究核反应压力容器控制棒驱动机构(Control rod drive mechanism,CRDM)管座中心J形坡口接头中焊接残余应力的分布规律,并将焊接残余应力场导入到含裂纹的三维CRDM管座接头模型中,直接计算得到焊接残余应力与工作内压和温度载荷偶合作用下的裂纹前沿等效应力强度因子Keq的分布规律。计算结果表明:焊后CRDM管座接头区中的环向残余应力远高于轴向残余应力;受焊接残余应力分布的影响,裂纹前沿Keq的最大值并非出现在裂纹前沿最深处,而是出现在裂纹下半部分靠近焊缝处;裂纹深度比a/δ的增加所引起的Keq的增加远大于裂纹长度2c的增加所引起的Keq增加。接头区的裂纹在其前沿实际Keq分布的控制下将以自然形态扩展,而并非以目前标准规范中假设的半椭圆形态扩展。为进行准确的裂纹扩展分析和安全评价,需要基于详细的有限元计算,给出考虑焊接残余应力影响下的裂纹前沿Keq的分布。The thermo-elastic-plastic finite element simulations are conducted to investigate the distributions of the weld residual stresses in the J-weld for a center-hole control rod drive mechanism（CRDM） nozzle and the full residual stress solution from the weld analysis is mapped directly to the three-dimensional finite element model with a crack,then the equivalent Keq-solution along crack front is extracted after application of the operating pressure and temperature.The results from these analyses show that the hoop residual stresses are much higher than the axial residual stresses in the CRDM nozzle.The peak stress intensity factor always appears in the front of the crack near the J-weld zone rather than at the center of the crack because of the high tensile weld residual stress in the J-weld.The increase of the stress intensity factor Keq caused by the increase of crack depth ratio a/δ is much higher than that caused by the increase of crack length 2c.The crack in the CRDM nozzle near the J-weld zone will grow in a nature shape which is controlled by the actual distribution of the stress intensity factor along the front of the crack,and does not grow in the semi-elliptical shape which is assumed by the present codes.For conducting the accurate crack growth analysis and safety assessment,the detailed finite element analyses are required to determine the weld residual stress fields and the stress intensity factor Keq values along the front of the cracks.

关 键 词：应力强度因子 焊接残余应力 轴向裂纹 控制棒驱动机构 J 形焊接接头 有限元 

分 类 号：TG156[金属学及工艺—热处理]