旋转抛物-锥形蚀坑模型及其应用

Rotating parabolic-conical corrosion pit model establishment and its application

点蚀是腐蚀介质环境中金属性能劣化的主要形式之一。蚀坑导致的应力集中会使结构整体强度退化,降低结构的安全性和可靠性。因此,准确的蚀坑模型对结构应力场的分析具有重要影响。为此,在典型的蚀坑形貌基础上,结合蚀坑张开角的定义,提出旋转抛物-锥形蚀坑模型,并通过有限元仿真与拉伸破坏试验验证了模型的有效性。结果表明:蚀坑导致的应力集中极大值处于接近坑底或坑口区域,旋转抛物-锥形蚀坑模型在蚀坑坑底、坑肩及坑口处的应力集中分布带比半椭球形蚀坑模型更准确,应力敏感性更强。

As one of the common degradation forms of metal structure exposed to the corrosive medium,pitting may cause the local stress concentration and decrease the strength,reliability and safety of the structure of equipment.Thus,an exact pit model is useful for the stress distribution analysis of the metal structure exposed to the corrosive medium.In this instance,by surveying the pattern of typical corrosive pitting,the concept of pit open angle is redefined,and a novel model called rotating parabolic-conial model is developed.Both FEM simulations and tensile experiments are performed to validate the accuracy and efficiency of the proposed model.It is shown that the maximum of the stress concentration caused by the pitting is generally located around the bottom or mouth area of the pit.Compared with the semi-ellipsoid model,the former is more accurate and sensitive on the description of the stress distribution around the bottom shoulder and mouth of a pit.