基于内聚力模型的X65管线钢稳定裂纹扩展研究

Study of stable crack growth through X65QO pipeline steel using cohesive zone modeling

断裂破坏是海工结构中主要的失效模式之一。对管线钢管的断裂韧度评定以及其裂纹扩展行为的模拟研究,对于评估管道结构的安全性、结构完整性有重要的指导意义。在众多用于模拟裂纹大变形稳定扩展的理论中,内聚力模型方法(CZM),对大范围屈服的断裂行为分析十分有效。它具有强大的物理基础以及可在数值方法中逐步实现的适应性。鉴于此,文章运用CZM模型对X65管线钢双引伸计法的断裂韧度试验进行模拟,对比计算与试验结果。研究了不同CZM模型参数对模拟结果的影响,并优化了模型。用其作为计算模拟预测X65管线钢稳定裂纹扩展行为的方法,可替代部分实验来完成可靠性评估。

Fracture failure is one of the major failure modes in offshore structures, which makes the assess-ment of fracture toughness and the investigation of crack growth on pipeline steels great significance on e-valuating the safety and structure integrity. Among the many theories for simulation of a large scale crack extension, the cohesive zone model （CZM） is very efficient on analyzing fracture events in the condition of large-scale yielding. It has strong physics basis and ease in numerical implementation. Therefore, in this paper, the CZM is utilized to simulate the fracture toughness test of X65 pipeline steel, which is processed by ＇Double Gauge Method＇. By comparing the simulation results and the experimental results, the influ-ence of variables in CZM is investigated and the CZM for the simulation and prediction of X65 pipeline steel stable crack growth is improved. By using the improved CZM, a portion of the experiment can be sub-stituted by simulation in safety assessment.