Analysis On Crack Propagation Of Buried Pipeline Damage

With the rapid economic development of modern society, city of underground pipenetwork is becoming more and more complicated, involving many important lifelineprojects known as the underground pipes, such as oil, gas, water and heating pipes. Thesepipelines in case of damage, which bring serious disaster to people’s lives. In the actualengineering, pipeline inevitable defects or cracks, these cracks are accumulated to acertain extend and final fracture occurs suddenly, causing malign accident.In order to simulate with initial cracks of pipeline crack propagation, using largefinite element analysis software ADINA to establish the structure formation+pipe of the3D Rupture model, so as to determine the initial position of crack. Though analysis andcomparison of the results can be seen, as the pipe wall thickness increases, resistance ofpipe axial strains and circumferential stresses capacity increases, the pipe is not easy tobe destroyed. When the pipeline diameter is large, the stress increases first and thendecreases, so choosing appropriate diameter beneficial to the project. Under the differentfault dip, it can be seen angle changes of significant impact on axial stress of piping.Analysis of pipeline without considering the friction and consider different frictioncoefficient of stress and strain of pipeline, found that when not consider friction, the axialstress, axial strain and the effective stress are bigger, instead, with the increase of frictioncoefficient, the corresponding stress decreases gradually. That when the displacementload is small, the friction on the pipeline damage mitigation the effect of the axial.The Fracture module in ADINA can be analyzed by2D finite element model of thecrack propagation. Therefore, it established including initial crack tip point and knowncrack propagation path of the plane strain model. The results show that the J integral indifferent line contour keeps a good conservation in the crack begins to crack andexpansion, and the stress diagram of the crack tip and ligament area meet the simpletheory of ideal elastic-plastic material in small scale yielding.