基于有限元的管道焊缝裂纹干涉问题研究

建立了管道焊缝双裂纹的有限元模型，分析双裂纹尺寸和裂纹尖端距离对裂纹应力强度因子的影响，讨论了裂纹干涉的规律，拟合出双裂纹间距离比和尺寸比对裂纹应力强度因子放大系数影响规律的计算公式.研究了焊缝区双裂纹干涉的规律.结果表明:随着两裂纹尖端距离增大，放大系数与距离比、尺寸比的关系为指数关系，其中距离比对放大系数的影响指数接近为-1，尺寸比对放大系数的影响指数接近为2.同时，基于干涉规律及结果，对裂纹进行ECA评估，同BS7910规范中对裂纹等效合并后的评估结果比较，拟合公式考虑了干涉效应的影响，评估结果较为准确，而BS7910规范评估结果或过于保守或过于乐观. 

Research on Interaction of Weld Cracks in Pipe Based on Finite Element Method

About the effect of crack interaction on the pipe welding line,two cracks interaction model was constructed based on finite element method in this paper.Considering the factors of crack dimension and distance,a fitting formula was proposed for stress intensity factors and crack dimension and distances between them.And also an interaction law was discussed.Results show that,with the increase of crack tip distance,the amplification coefficient decreases according to the negative exponential law,tending to 1 finally.And the influence of crack dimension on interaction law is approximately quadric positive correlation.Based on the interaction law and research results,the engineering critical assessment (ECA) for cracks was carried out.Compared with the crack evaluation results with BS 7910 criterion,the proposed fitting formula,which takes interaction effect into consideration,can provide more accurate evaluation results.