管道钢断裂韧性尺寸效应的研究  

RESEARCH ON SIZE EFFECT ON FRACTURE TOUGHNESS OF PIPELINE STEEL

作　　者：甄莹[1,2] 衣海娇 曹宇光 张士华[3] 史永晋 ZHEN Ying;YI HaiJiao;CAO YuGuang;ZHANG ShiHua;SHI YongJin(Province Key Laboratory of Safety of Oil&Gas Storage and Transportation,China University of Petroleum y Qingdao 266580,China;State Key Laboratory for Strength and Vibration of Mechanical Structures,Xi'an 710049,China;Drilling Technology Research Institute of Shengli Petroleum Engineering Corporation Limited,SINOPEC,Dongying 257055,China)

机构地区：[1]中国石油大学(华东)山东省油气储运安全重点实验室,青岛266580 [2]机械结构强度与振动国家重点实验室,西安710049 [3]中石化胜利石油工程有限公司钻井工艺研究院,东营257055

出　　处：《机械强度》2019年第6期1436-1444,共9页Journal of Mechanical Strength

基　　金：国家重点研发计划课题(2016YFC0802306);中央高校基本科研业务费专项资金项目(18CX06036A);国家自然科学基金项目(11472309);强度与振动国家重点实验室开放课题项目(2017-KF-02)资助~~

摘　　要：断裂韧性作为评估管道结构完整性的一个重要参数,对其进行尺寸效应研究具有重要的科学意义和工程价值。当前对金属材料断裂韧性尺寸效应的研究主要集中于线弹性断裂参数应力强度因子K,且大多仅考虑试件厚度的影响。为建立试件尺寸对高强度高韧性管道钢材料断裂韧性的系统影响规律,基于Gurson-Tvergaard-Needelman (GTN)模型对单边切口梁(SENB)试件三维断裂过程进行模拟,选用裂纹尖端张开位移(CTOD)与裂纹尖端张开角(CTOA)对其断裂韧性进行表征,分析两者沿试件厚度的分布规律,并研究裂纹深度与试件厚度对其影响。同时选取应力三轴度对试件约束水平进行评估,以此解释断裂韧性尺寸效应存在的原因。研究结果表明:断裂韧性在试件厚度方向一定范围内基本保持不变,在自由表面处取得最大值;裂纹深度对断裂韧性几乎没有影响,而试件厚度越大,断裂韧性越低,且临界CTOA比临界CTOD更能反映断裂韧性的变化规律。As a parameter characterizes the ability to resist crack propagation,fracture toughness plays an important role in evaluation of pipeline integrity.It is of both scientific and engineering significance to carry out a thorough study on its size effect.At present,the research on size effect of fracture toughness of metal materials is mainly focused on the linear elastic fracture parameter stress intensity factor K,and mostly only the influence of specimen thickness is considered.In order to establish a systematic law of size effect on high strength and high toughness pipe steel,a three-dimensional finite element model of standard single-edge notched beam(SENB)specimens based on GTN model was set up.The ductile fracture process of this specimens under displacement load was simulated.The Crack-tip Opening Displacement(CTOD)and Crack-tip Opening Angle(CTOA)were selected to characterize the fracture behavior.The distribution law of them along the specimen thickness direction was analyzed,and the effects of crack depth and specimen thickness were also studied.At the same time,the stress triaxiality was selected to evaluate the constraint level,so as to explain the cause of the size effect.The results show that the fracture toughness along the thickness direction remains unchanged within a certain range and reaches peak value at the free surface.The crack depth has little effect on fracture toughness and it decrease with the increase of specimen thickness.

关 键 词：CTOD CTOA 应力三轴度 尺寸效应 约束 

分 类 号：O346.1[理学—固体力学]