输气管道裂纹动态扩展的影响因素分析

输气管道裂纹的止裂是保障管道安全可靠性的前提，而管道裂纹动态扩展的驱动力则是表征裂纹扩展或止裂的直接因素。通过建立输气管道裂纹动态扩展的有限元模型，并在模拟计算中考虑裂纹扩展速度的衰减，分别计算了表征动态裂纹扩展驱动力的两项参数--能量释放率和裂纹尖端张开角；进而分析了管道内压、壁厚、裂纹止裂长度和初始裂纹速度对裂纹驱动力（也即裂纹扩展）的影响。最后得出结论：①管道内压对裂纹驱动力的影响很大，在其他条件不变，内压越大的管道裂纹驱动力越大；②管道壁厚也是对裂纹驱动力影响较大的一个因素；③随着止裂长度的增加，裂纹尖端张开角也随着增大；④最大裂纹速度越高，裂纹越不容易止裂。

DETERMINANTS FOR CRACK DYNAMIC PROPAGATION OF GAS TRANSMISSION LINE

Crack arrest of gas transmission line is the premise of pipeline safety and reliability. The driving force of pipeline crack dynamic propagation is the determinant of pipeline crack propagation or arrest. Two parameters of the crack dynamic propagation driving force, energy release rate and crack tip opening angle, are calculated by establishing a finite element model of the crack dynamic propagation in gas pipelines and considering the attenuation of the crack propagation velocity. Meanwhile, the influences of pipeline internal pressure, wall thickness, crack arrest length and initial crack velocity on the crack driving force (crack propagation) are further studied. The study results are given below: ①pipeline internal pressure is a major determinant to crack driving force, i.e. the higher the pressure is, the bigger the crack driving force will be; ②wall thickness is a major determinant to crack driving force; ③the crack tip opening angle will scale up while increasing the crack arrest length; ④the higher the maximal crack velocity is, the harder for the crack arrest will be.