Ramifications of Structural Deformations on Collapse Loads of Critically Cracked Pipe Bends Under In-Plane Bending and Internal Pressure
Ramifications of Structural Deformations on Collapse Loads of Critically Cracked Pipe Bends Under In-Plane Bending and Internal Pressure
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DOI：
10.1016/j.net.2016.09.001
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发表时间：
2017-02
影响因子：
2.7
通讯作者：
S. Sasidharan;Veerappan Arunachalam;Shanmugam Subramaniam
中科院分区：
文献类型：
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作者：
S. Sasidharan;Veerappan Arunachalam;Shanmugam Subramaniam
采用理想弹塑性有限元分析方法，研究了结构变形对含环向穿透裂纹的90°弯管在面内闭合弯曲和内压作用下失稳载荷的影响。临界裂纹定义为在拱背处具有对向角的贯穿壁周向裂纹，低于该对向角时，对承受面内闭合弯曲的弯头的倒塌力矩没有削弱作用。在弯曲区域假设椭圆形和半椭圆形横截面并进行比较。采用二次弹性斜率法计算了结构的破坏荷载。结构变形，即椭圆度和减薄，分别从0%到20%，以5%的步长变化，标准化内压从0.2到0.6变化。结果表明，椭圆形截面适用于管比5和10，而对于管比20，半椭圆形截面给出了令人满意的解决方案。椭圆度对破坏载荷的影响是显著的，尽管在一定的内压值下它被抵消了。减薄对考虑裂纹几何形状的弯曲件的破坏载荷的影响可以忽略不计。
Finite-element analysis based on elastic–perfectly plastic material was conducted to examine the influence of structural deformations on collapse loads of circumferential through-wall critically cracked 90° pipe bends undergoing in-plane closing bending and internal pressure. The critical crack is defined for a through-wall circumferential crack at the extrados with a subtended angle below which there is no weakening effect on collapse moment of elbows subjected to in-plane closing bending. Elliptical and semioval cross sections were postulated at the bend regions and compared. Twice-elastic-slope method was utilized to obtain the collapse loads. Structural deformations, namely, ovality and thinning, were each varied from 0% to 20% in steps of 5% and the normalized internal pressure was varied from 0.2 to 0.6. Results indicate that elliptic cross sections were suitable for pipe ratios 5 and 10, whereas for pipe ratio 20, semioval cross sections gave satisfactory solutions. The effect of ovality on collapse loads is significant, although it cancelled out at a certain value of applied internal pressure. Thinning had a negligible effect on collapse loads of bends with crack geometries considered.