套管内壁球形腐蚀坑洞的应力集中效应研究

研究点蚀坑应力集中分布规律对套管防护和寿命预测具有重要意义。基于球形腐蚀坑模型,采用有限单元法对球形点蚀应力集中问题进行数值模拟,得到了应力集中系数随套管壁厚、腐蚀深度等参数的变化曲线,分析了双坑以及点蚀群情况下应力集中系数的变化规律,并将所得结果与理论计算结果进行了比较。分析结果表明,数值模拟在一定程度上验证了理论公式的正确性,应力集中系数随腐蚀深度的增加而变大;应力集中系数主要与h/d(腐蚀坑洞的深度与开口直径之比)的变化有关,套管的壁厚对应力集中系数影响较小;双坑点蚀交汇能够增大应力集中。

Research on the Stress Concentration Effect of Global Corrosion Cavity of Casing Inner Wall

Research on the stress concentration distribution law of pitting corrosion cavity is of vital importance to casing protection and its service life prediction.Based on the global corrosion cavity model,the finite element method was adopted to conduct a numerical simulation of global pitting stress concentration to obtain the variation curve of stress concentration coefficient with the parameters such as casing wall thickness and corrosion depth.The variation law of stress concentration coefficient in the case of double cavity and pitting group was analyzed.The result obtained was compared with the result obtained by theoretical calculation.The analysis shows that the numerical simulation verifies the correctness of the theoretical formula to some extent.The stress concentration coefficient increases with corrosion depth.The coefficient is mainly related to the change of h / d.The casing wall thickness has relatively small effect on the coefficient.The pitting convergence of double cavity can increase stress concentration.