X60管钢的J-A_2双参数弹塑性断裂预测

Elastoplastic Fracture Assessments of Pipelines Steel X60 by J-A_2 Two Parameter Approach

在对X60管钢弹塑性断裂分析中,采用J-A2双参数方法来预测带表面裂纹管道的破坏压力。为将实验室得到的X60钢标准试件的JR-Δa曲线的实验数据应用到实际裂纹构件中,对单边缺口紧凑拉伸(CT)试件和带轴向表面裂纹管道进行有限元分析。用J-A2方法来量化裂纹尖端区域的约束情况,结果表明,在裂纹深度相同的情况下,管道的内侧和外侧裂纹端的约束水平基本接近,内侧裂纹的略高一些,但二者与CT试件裂纹端的约束水平相比要低一些。同时,根据带裂纹管道的有限元计算结果,对管道的断裂破坏压力进行了预测,内侧裂纹的断裂破坏压力比外侧裂纹时的稍低。对X60管钢,断裂力学预测结果要比PCORRC准则的预测结果低。

In the elastoplastic fracture analysis for pipelines steel X60, J-A2 two parameter approach was adopted to predict the failure pressures of pipelines with surface cracks. In order to apply the experimental JR-Δα curves measured by standard laboratory specimens of steel X60 to real cracked components, the finite element analyses were performed for a single edge notched compact tension （CT） specimen and pipelines with axial surface crack. The J-A2 solution was used to quantify the constraint condition in the crack-tip fields. It shows that the inner crack-tip constraint levels of pipelines are close to the exterior ones with the same crack depth. The inner crack-tip constraint levels are slightly higher relatively. But their crack-tip constraint levels are lower than CT specimen. From the result of finite element analysis for pipelines, the fracture failure pressures of pipelines were predicted. The fracture failure pressures with fracture mechanics analyses are lower than those with PCORRC for pipelines steel X60.