以临界CTOA为参量的含裂纹管道极限压力有限元模拟

Finite element simulation of limit pressure pipe line with cracks using critical crack-tip-opening-angle

关键词:  天然气管道  穿透裂纹  临界CTOA  极限压力

Key words:  gas pipeline  penetratig crack  critical crack tip opening angle  limit pressure

摘要:

以裂尖张开角度(CTOA)为断裂参量,采用有限元方法,研究了含轴向穿透裂纹管道极限压力及影响因素,建立以材料临界CTOA为失效条件的极限压力预测模型。结果表明,只要采用合适模型以及恰当的单元尺寸,应用材料临界CTOA可以有效预测含穿透裂纹管道的极限压力。现有预测模型在小裂纹时严重低估管道承载能力,但对较大裂纹,则过高估计了极限压力,给管道安全带来隐患。

Abstract:

The limit pressure of pipeline with cracks is one of the important aspects in structure integrity assessment.We used finite ele-ment method,crack tip opening angle(CTOA) as the parameter to in-vestigate the applicability of critical CTOA in pipe line limit pressuremod-cling,which containing longitudinal penetrating crack.Here the critical CTOA was used as the critical failure rule of the pipe.Factors affectingnum erical results were also studied.Then a predictive model was estab-lished based on these results and compared with other models.From theanalysis,we could conclude that critieoula CTOA could be used t0 mode.ling penetrating crack in pipelines as long as the finite element model and element size were properly chosen.When the crack was small the known formulas would heavily underestimate pipe carrying capacity.But for largecracks,they might give overestimated results,and lead to safety problem sfor pipes.