约束修正失效评定曲线及内压管道失效分析

Constraint-based failure assessment curve for X80 pipeline steel

用A2参数描述裂纹尖端约束效应,考虑裂纹尖端约束水平对断裂阻力的影响,对R6失效评定曲线进行修正。以X80钢为例,根据不同约束水平试件测试得到的JR–△a曲线,给出了与裂纹尖端约束相关的失效评定曲线。在使用有限元对带裂纹内压管道进行弹塑性分析的基础上,利用失效评定曲线对失效载荷进行预测;与试验结果比较表明:采用约束修正失效评定曲线,在对存在缺陷的构件进行安全性评定、寿命评估、失效概率计算时,考虑约束效应对断裂韧度的影响可以更充分地发挥构件的强度潜力。

The A2 parameter is addressed to describe the constraint effect at crack-tip fields.Considering the influence of the constraint to the fracture toughness, the R6 failure assessment diagram is modified. According to some JR-△a curves of different constraint levels for X80 steel. The constraint-based failure assessment curve is established for X80 pipeline steel. Some internal-pressure pipelines with axial crack are calculated by finite element analysis approach. The predicted results from the constraint-based failure assessment curve and the current R6 failure assessment curve are compared with the test results. It is shown that the constraint-dependent fracture mechanics data may be included in a framework for assessing defects and the constraint-based failure assessment approach may exploit fully the potential of the components.