考虑残余应力的弹塑性断裂参量计算方法

Study on method of elastic-plastic fracture parameters considering residual stress

核电厂承压设备的断裂安全性能评价中均要求考虑焊接或矫形过程形成的残余应力(RS)的影响,但如何快速、可靠地计算复杂载荷下裂纹前沿的弹塑性断裂参量,一直是工程中的技术难点。针对材料拉伸性能符合R-O关系的结构,基于英国R6规范的双参数失效评定图(FAD)技术,采用理论推导的方法,提出一种线弹性断裂参量应力强度因子(SIF)的塑性修正方法。该方法在理论基础方面优于现有RCC-M和ASME规范中对SIF直接塑性修正的方法。分析案例表明,焊接和矫形过程形成的RS对结构断裂性能存在明显影响。

Although it is required to consider the influence of residual stress(RS)generated in the process of welding or shape correction in the fracture safety assessment of nuclear plant equipment,how to quickly and reliably calculate the elastic-plastic fracture parameters along the crack front under complex load conditions in the engineering has been being a technical difficulty.For the structures whose tensile properties satisfy the R-O relationship,a plastic correction method of linear-elastic fracture parameter(stress intensity factor,SIF)was derived based on the R6 Code which is called as a two-parameter failure assessment diagram(FAD)method.The method is superior to the direct plastic correction method of SIF in RCC-M and ASME Codes in terms of theoretical basis.It is shown that there is obvious influence on structural fracture performance for RS generated in welding and shape correction process in the studied case.