基于Oyane韧性断裂准则的凹陷管道损伤程度研究

STUDY OF THE DAMAGE DEGREE OF DENT PIPE BASED ON OYANE DUCTILE FRACTURE CRITERION

管道凹陷的深度对于X60管线钢安全性有不同程度的影响,采用Oyane韧性断裂准则与数值模拟相结合的方法对凹陷管道损伤程度进行研究。通过有限元软件建立了三维球形凹陷缺陷管道模型并求解模型,探讨了管道内压以及压头尺寸对凹陷深度与油气管道损伤程度之间关系的影响规律。研究结果表明:管道凹陷深度在一定的范围内,内压对管道抵抗韧性破裂是有利的。当凹陷深度超过100 mm时,内压会使管道损伤程度明显增大。在壁厚与管径比值、管道内压不变的情况下,压头尺寸越小损伤程度随凹陷深度增加越严重。而在一定条件下,当管道凹陷深度超过标准规定的7%管径时,管道损伤程度仍然满足积分值I<1。基于凹陷深度评价标准存在局限性,所以Oyane韧性断裂准则可应用于工程上管道凹陷的评价。

The depth of the pipeline depression has different influence on the safety of X60 pipeline steel,combining Oyane ductile fracture criterion with numerical simulation method to study damage degree of the pipeline. Establishing three dimensional spherical concave defect pipeline model by finite element software and solving the model,discussing internal pressure influence of the pipeline and the indenter size on the relationship between the depth of sag and the damage degree of oil and gas pipelines.The results show that： when the depth of the pipeline depression is in a certain range the internal pressure is beneficial to resist ductile rupture. Once the depth of the pit exceeds 100 mm,the internal pressure will increase the extent of damage of the pipeline.In the case of the ratio of wall thickness to pipe diameter and the constant pressure in the pipe,the smaller the size of the indenter,the more serious the damage degree increases with the depth of the depression. Under certain conditions,when the pipe sag depth exceeds the standard 7% pipe diameter,the degree of pipe damage still meet the integral value I 1. The Oyane ductile fracture criterion can be applied to the evaluation of sags in engineering projects because of the limitation of sag depth evaluation criteria.