动态载荷作用下焊接点线弹性裂纹的弯曲扩展路径的预测(英文)

利用二阶摄动方法研究了动态载荷作用下结构线弹性断裂裂纹的弯曲延伸扩展问题并求解了动态应力强度因子。利用二阶摄动方法研究了动载荷作用下裂纹路径预测时的应力准则与能量准则之间的关系。就均匀物质而言,在二阶摄动分析理论的框架内,两种准则指明了相同的动态裂纹路径。但在具有非均匀断裂韧度的物质中,能量准则优越于应力准则。作为二阶摄动方法的实际运用,研究了焊接结构中动态线弹性裂纹的形态特征和弯曲扩展路径问题,综合考虑了诸如远场动态作用应力、焊接残余应力、局部物质衰变以及不同尺寸的缺陷的存在等因素,绘制出动态载荷作用下退化区域中裂纹弯曲扩展的临界轨迹曲线。

Crack Path Prediction of Brittle Fracture in Weldment under Dynamic Loads

Dynamic stress intensity factors are analyzed for a non-collinear crack by using a second order perturbation method.The method is extended to obtain an approximate representation of dynamic stress intensity factors at the tip of a straight crack with a slightly branched and curved extension.Having examined the near tip asymptotic stress field,the effects of far field boundary conditions are taken into account in the sense of a matched asymptotic expansion.A dynamic energy release rate due to non-collinear crack growth can be calculated by using Irwin’s formula.The branched crack extension in materials with inhomogeneous fracture toughness is considered.Paths of brittle cracks propagating along a welded joint are predicted as a practical application of this method,where the effects of dynamic applied stresses,residual stresses,and material deterioration due to welding are taken into considerations.