含Ⅰ-Ⅱ型混合裂纹X80管线钢断裂特性研究

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中图分类号：TH123 文献标识码：A DOI： 10.7535/hbgykj.2026yx01007

Abstract：Inorder to obtain the fracture failure criterion for X8O pipeline steel with I-IIcompositecracks，flat plate specimens withcentercracks ofdiferentanglesandlengthswereusedtodeterminetheultimateloadandfracturedisplacement of X80 pipelinestel.Atthesametime，theextendedfiniteelement method（XFEM）wasused to solvetheultimateloadof the center crack plate and the stress intensity factors Ki and KII at the crack tip. The equivalent stress intensity factor Keq was calculated according to the energy release rate criterion. Finally，the equivalent stress intensity factor Keq was corrected using experimentaltestingandnumerical simulationresults toobtainthefracturecriterionapplicable to X8opipeline stel.The results show that when thecrack length issmall，thecrack has litleeffectontheultimate load，and the fracture of X80 pipelinestel specimenconforms tothecharacteristicsofductilefracture.Asthecrack length increases，theinfluenceof the crack on the ultimate load gradually increases. When the crack length is 70mm ，the ultimate load of the specimen with angle γ=0∘ decreases by 59.67% and the fracture of the X8O pipeline steel specimen conforms to the characteristics of brittle fracture. Therefore，the fracture of specimens with Type composite cracks exhibits both ducitle and brittle fracture characteristics，andtheenergyreleaserate criterioncannot bedirectlyused for failure determination.Thereisacertaingap between the calculated equivalent stress intensity factor Keq and the fracture toughness KIC of X80 pipeline steel. However，by introducing the correction factor A obtained through experimental and numerical simulation data fitting，the failure criterion can predict the ultimate fracture load of X8O pipeline steel with type composite cracks well，with an error of less than 3.5% .Theresearch result has significant implications for improving the accuracy of integrity evaluation results for cracked plate and shellstructuresunder two-dimensional stressconditions，such aslong-distance oil and gas pipelines under internal pressure.

Keywords：fracture mechanics； X8O pipeline stel； stressintensity factor；fracture characteristics；energy release rate

X80管线钢广被泛应用于油气长输管道[1-3]，由于加工制造、腐蚀等原因，可能存在裂纹缺陷，危害管道安全[4-7]，因此研究含裂纹结构的X80管线钢的断裂特性，对于保障油气长输管道安全运行具有显著意义[8-11]。（剩余10659字）