电偶腐蚀对接触电极间压紧力的影响

电偶腐蚀会导致受载结构中内力的变化,从而改变结构性能。研究电偶腐蚀对结构内力的影响规律,利于提高相关结构的设计水平。设计接触端面为圆平面的圆柱形电极,采用恒位移加载方式使两个接触面相互压紧,同时将电极浸泡在质量分数3.5%的NaCl溶液中进行腐蚀,测试给出了压紧力随腐蚀时间的变化曲线。与实验状态相对应,用电极表层腐蚀区的径向和轴向尺寸以及等效弹性常数表征电偶腐蚀效应,根据实验观察近似取定腐蚀区尺寸,建立微观尺度的材料性能模拟模型和宏观尺度的结构力学模拟模型,计算给出了腐蚀区的材料性能参数和腐蚀一定时间后电极之间的压紧力,计算结果与实验结果大致吻合。该项研究同时为数值模拟电偶腐蚀对结构力学行为的影响提供了新的方法。

Effects of galvanic corrosion on compressive force between two galvanic electrodes

The structural internal forces as well as properties may be changed by galvanic corrosion. Studying and understanding the laws of galvanic corrosion effects on structural internal forces is useful for promotion of design level. The experiments and measurements of macro compressed loading and corrosion for a pair of galvanic electrodes subjected to fixed displacement loading are performed and the curve of the compressive force between the galvanic electrodes versus corrosion time is obtained. According to the corroded surface morphologies obtained by scanning electron microscope (SEM) after rust cleaning, the meso-scale finite element model for the corroded zone is developed by using the homogenization method in terms of representative volume element (RVE) and the equivalent elasticity constants of the corroded zone are computed. Meanwhile, the sizes of the corroded zone are determined approximately by the corroded surface morphologies and a macro-scale finite element model for the whole sample is developed and the compressive force is calculated which basically agrees well with the experimental value. Therefore, a new method to numerically simulate the influences of galvanic corrosion on structural mechanical behavior is developed.