基于拘束的X80钢裂纹扩展阻力曲线构建

对于管道中的裂纹，由于其裂纹尖端拘束水平低，使用单边缺口弯曲试样、紧凑拉伸试样所测得的裂纹扩展阻力曲线对管道进行断裂评估，得到的结果趋于保守. 文中采用裂纹深度不同的单边缺口拉伸试样，探讨了裂纹深度对裂纹扩展阻力曲线的影响. 采用有限元分析，计算了裂纹深度不同的单边缺口试样的裂纹尖端拘束水平. 最后，基于裂纹尖端的拘束水平，所构建的裂纹扩展阻力曲线能更加准确地表征管道中裂纹的扩展阻力曲线.

Construction of J-R curve for X80 steel based on constraint level

Since the constraint level at crack tip is lower in pipeline cracks, the results of fracture assessment for pipelines are conservative by adopting the J-R curves determined by the traditional single edge bend specimens and compact tension specimens. In this paper, we investigated the effect of crack depth on the J-R curve by adopting the single notch tension specimen with different crack depths. Based on finite element analyses, we calculated the constraint of crack tip for single notch tension specimens with different crack depths. The J-R curve constructed based on the constraint level at the crack tip can accurately characterize the J-R curve for cracks in X80 pipeline steel.