两裂纹相互作用对管道应力强度因子的影响

1. 西北大学化工学院;2. 陕西延长石油(集团)有限责任公司研究院;3. 西安交通大学化工学院

X80 钢制管道;三维表面裂纹;裂纹尺寸;裂纹间距;应力强度因子;相互作用

Effect of the interaction between two surface cracks in a pipeline on the stress intensity factor
LI Wei1, DAN Yong1, WU Wei1, WANG Ke2, ZHAO Hengrui3, WANG Litao1

1. School of Chemical Engineering, Northwest University; 2. Research Institute of Shaanxi Yanchang Petroleum (Group)Co. Ltd.; 3. School of Chemical Engineering and Technology, Xi'an Jiaotong University

X80 steel pipe, three-dimension surface crack, crack size, crack spacing, stress intensity factor, interaction

备注

针对油气输送管道内表面两裂纹相互影响的情况,运用有限元方法,模拟分析了X80 钢制管道内三维表面裂纹尺寸、裂纹间距对裂纹应力强度因子的影响规律。研究结果表明:两裂纹(分别为固定裂纹与可变裂纹)的间距越大,两裂纹相互作用越小,当间距达到或超过一定值时,对应力强度因子几乎不产生影响,仅需考虑主要裂纹对管道寿命的影响;可变裂纹的相对壁厚比越小或形状比越大,两裂纹相互作用越小,当相对壁厚比小于0.2 或形状比大于0.8 时,可以忽略其对应力强度因子的影响,且形状比对最大应力的影响远远小于壁厚比与裂纹间距对最大应力的影响。(图8,参[20]

In order to study the interaction between two surface cracks in an oil and gas pipeline, the effecting laws of the size and spacing of three-dimension surface cracks in the X80 steel pipe on the stress intensity factor were analyzed in this paper by means of finite element method. It is shown that the larger the spacing between two cracks (fixed crack and variable crack) is, the smaller their interaction is. When the spacing reaches or exceeds a certain value, its effect on the stress intensity factor is negligible, and only the effect of main cracks on the pipeline life shall be taken into consideration. With the decrease of the relative wall thickness ratio of the variable crack or with the increase of the shape ratio of the variable crack, the interaction between two cracks decreases. When the relative wall thickness ratio is lower than 0.2 or the shape ratio is higher than 0.8, its effect on the stress intensity factor is negligible, and the effect of the shape ratio on the maximum stress is much less than that of the wall thickness ratio and crack spacing on the maximum stress. (8 Figures, 20 References)