管道弯管区裂纹的断裂力学参数KJ计算研究

Calculation research of fracture mechanics parameters KJ of cracks in elbows

弯管作为核电站管系中重要的组成部分,其压力边界的完整性直接影响到核电站的可靠运行。因此,对含缺陷的弯管区进行相应的分析来评价其是否满足安全性要求很有必要。分析评价用到的主要断裂力学参数是应力强度因子K和J积分。针对管道弯管区断裂力学计算中最为关键的复杂的有限元网格模型,本文提出了一种程序化、分块化的快速的三维建模流程,并给出了其在内压和弯矩作用下的应力强度因子K和J积分计算分析的实例。研究表明,分块化的建模思想可以较为快速地解决管道弯管区断裂力学计算中复杂的建模问题,也可以为建立其他含裂纹的结构有限元模型并进行断裂力学参数KJ计算积累经验。

Background： Elbows are important constituent parts of piping systems in nuclear power plant. The pressure boundary integrity of elbows direct influences reliability of nuclear power plant operation. Purpose： Therefore, it is necessary to carry out analysis of the cracked elbows to evaluate whether the safety requirement is satisfied. Methods： The principal fracture mechanics parameters required in analysis and evaluation are stress intensity factor K and J integral. The most important procedure for calculating fracture parameters K/J is to build up correct and reasonable mesh using finite element method. Results： In this paper, a fast programmed and partitioned three dimensional modeling procedure was proposed, which is useful to model the complex finite element model in fracture mechanics calculation, and calculation case of KJ of cracked elbows which subjected to inner pressure and in-plan moment was given based on the modeling method. Conclusions： The results prove that the programmed and partitioned modeling method developed in this paper could solve the complex modeling issue in fracture mechanics calculation of cracked elbow, as well as offer experiences for modeling other cracked components and calculating fracture mechanics parameters KJ.