影响凹陷管道安全因素分析

为了分析管道上凹陷对其安全性的影响，以非线性接触模型为基础，应用ABAQUS有限元软件，建立矩形状压头作用于管道的三维模型。通过求解模型，探讨了凹陷深度、凹陷位置、凹陷尺寸、管道内压对管道轴向应变和韧性失效损伤因子的影响。结果表明:管道的轴向应变随着内压的增大而增大，然而内压的存在却对管道韧性失效起到一定的抑制作用。当韧性失效损伤因子D=1时可以通过韧性断裂准则预测其临界失效应变；当凹陷深度超过一定范围内压会使损伤程度增大；当凹陷位置为垂直于管道正上方时，其对管道的轴向应变及韧性失效损伤因子的影响较大；当管道内压一定时，随着凹陷变形量的增加，与凹陷轴向长度相比，凹陷宽度的变化对管道的轴向应变及韧性失效损伤因子程度影响更显著，而增大凹陷长度和宽度均可有效降低其对管道安全性的影响。

Analysis on influence factors of dent pipeline safety

In order to study the influence of dent defect on the safety of pipeline, a three-dimensional model of rectangular pressure head acting on pipeline was established based on the non-linear contact model by using ABAQUS finite element software. Through solving the model, the influence of dent depth, dent location, dent size and internal pressure of pipeline on the axial strain and ductile failure damage indicator of the pipeline were analyzed. The results showed that the axial strain of pipeline increases with the increase of internal pressure, while the existing of internal pressure plays a certain inhibitory action on the ductile failure of pipeline. When the ductile failure damage indicator D=1, the critical failure strain can be predicted by the ductile fracture criterion. When the dent depth beyond a certain range，the damage of pipeline will increase. When the dent location is perpendicular to the upper of pipeline, it has greater influence on the axial strain and ductile failure damage indicator of the pipeline. When the internal pressure keeps constant, compared with the axial length of dent, the change of dent width plays a more obvious influence on the axial strain and ductile failure damage indicator of the pipeline with the increase of dent deformation amount, while increasing the length and width of dent can both reduce the influence on pipeline safety effectively.