油气管道内部轴向表面半椭圆裂纹弹塑性断裂分析

Elastic-Plastic Fracture Analysis for Internal Axial Surface Half Elliptical Cracks in Oil & Gas Pipeline

对油气管道内部轴向表面半椭圆裂纹进行了断裂分析,提出了改进的J积分估算公式。首先,基于使用形变塑性的详细三维FE计算,列表给出了部分以径厚比、裂纹深度与长度比、裂纹深度与管壁厚比、R-O材料应变硬化系数和半椭圆裂尖位置等为变量的J积分全塑性解。然后,通过对这些全塑性解分析指出EPRI分析方法中的不足之处。最后,以本次FE计算为基础,给出了沿裂纹尖端基于GE/EPRI的J积分预测公式,并通过对计算公式、EPRIJ积分估算公式与有限元计算结果的对比,说明提出公式的精确性,为油气管道的断裂评定奠定基础。

The elastic--plastic fracture analysis for internal axial surface half elliptical cracks oil ＆ gas in pipeline were provided and the corrected J -- integral estimation method was established. First, based on detailed 3 -- D FE results using deformation plasticity, some fully plastic solutions for fully plastic J components were tabulated for the mean radius-- to-- thickness ratio, the crack depth--to--length ratio, the crack depth--to--thickness ratio, the strain hardening index for the R --O material, and the location along the semi--elliptical crack front. Second, by means of the analysis of these fully plastic solutions for fully plastic J components, the improper of the EPRI method was described. Finally, based on the FE results, the GE/EPRI--type J estimation equation along the crack front was proposed. Then the J values calculated by FE, EPRI and the method were compared, which demonstrates the accuracy of the J--integral estimation method.