弯曲载荷下管道环焊缝裂纹应力强度因子评价模型及试验验证  

Evaluation and experimental verification of stress intensity factors for pipeline girth welds with crack defect under bending load

作　　者：田野 TIAN Ye(West Pipeline Company of PipeChina,Urumchi 830013,China)

机构地区：[1]国家管网集团西部管道有限责任公司,乌鲁木齐830013

出　　处：《压力容器》2023年第7期29-35,共7页Pressure Vessel Technology

摘　　要：裂纹缺陷是众多环焊缝缺陷中危险性最大的缺陷之一。油气管道在经过地质条件较差的区域时,当遭遇自然灾害,管道除内压作用外,还会承受额外的弯曲载荷,由此引起的大跨度管道弯曲变形容易引起环焊缝裂纹扩展,导致管道破裂。基于大量环焊缝裂纹有限元数据,拟合出了裂纹尖端应力强度因子的工程评估公式。按照子模型分析方法可以快速获得有限元结果数据且能保证精度,是一种高效获取全尺寸弯曲管道中裂纹应力强度因子拟合数据的方法。结合API 579中提供的环向裂纹应力强度因子理论公式,对应力强度因子计算公式进行了拟合,裂纹尺寸范围为0.03<a/c<0.2,0.27<a/t<0.54,对应的最大误差为4.86%。通过全尺寸弯曲试验,验证了裂纹扩展时对应的公式临界位移精确度可达5.49%,公式临界远场应变精确度可达4.95%。Crack defect is one of the most dangerous defects in girth weld.Once pipelines encounter natural disasters,they will bear additional bending load in addition to internal pressure,and the bending deformation easily causes girth weld crack propagation and pipeline rupture,when oil and gas pipelines pass through areas with poor geological conditions.The engineering evaluation formula of stress intensity factor at crack tip was fitted based on a large number of finite element data of girth weld cracks.The submodel analysis method can obtain the finite element result data quickly without losing the accuracy,and it is an efficient method to obtain the fitting data of crack stress intensity factor in full-scale bending pipeline.In combination with the theoretical formula of stress intensity factor for circumferential crack provided in API 579,the basic form of stress intensity factor was given.The crack size range was 0.03<a/c<0.2 and 0.27<a/t<0.54,and the corresponding maximum error was 4.86%.Through full-scale bending tests,it is verified that the critical displacement accuracy of the corresponding formula during crack propagation can reach 5.49%,and the critical far-field strain accuracy of the formula can reach 4.95%.

关 键 词：环焊缝 裂纹 应力强度因子 全尺寸弯曲试验 快速评估 

分 类 号：TH49[机械工程—机械制造及自动化] TH123[理学—固体力学] O346.1[理学—力学]