Optimization of Cathodic protection system by Boundary Element Method

提出了一种确定阴极保护系统最佳外加电流密度和最佳电极位置的边界元法。电解液中的电位用毒物方程来描述，该方程具有非线性边界条件，该边界条件是基于实验确定的电化学极化曲线来实现的。在被保护结构各部分的电势小于某一临界值的保护条件下，确定了最佳外加电流密度，以使保护所需的电源最小。采用共轭梯度法求解，并考虑了罚函数法的保护条件。提出了几种技术将上述方法应用于实际复杂结构。为了解决三维问题cpu时间长的问题，提出了一种有效的方法来求优化过程中所需的f势的导数。对于电极必须直接位于结构壁上的结构，对边界积分方程进行了修改，使设计变量与边界元网格无关，从而避免了通常优化过程中每次迭代所必需的重新网格划分。提出了一种用于预测细长构件结构的电场响应的三维边界元方法。提出了另一种有效的方法来分析由数千根不锈钢管连接到黄铜板上的热交换器的电偶腐蚀问题。利用模糊集和边界元方法，求解了由远离金属表面的某些点测得的电势值估算金属表面电流密度的反问题。应用边界元法处理了涂层腐蚀缺陷的识别问题。少

A boundary element method for determining the optimum impressed current densities and optimum location of electrode in a cathodic protection system was developed. The potential within the electrolyte was described by poison's equation with nonlinear boundary conditions which were enforced based on experimentally determined electrochemical polarization curves. The optimum impressed current densities were determined in order to minimize the power supply for protection under the protecting conditions that the electric potential of every part of the structure to be protected should be less than some critical value. The solution was obtained by using the conjugate gradient method in which the protecting conditions were taken into account by the penalty function method.Several techniques were proposed to apply the above method to a real complicate structure. In order to cope with the long cpu time for three dimensional problem, an effective method was proposed for obtaining the derivatives o … More f potential, which were needed in the optimizing procedures. For structures in which the electrodes must be located directly on the walls of the structures, the boundary integral equation was modified in such a way that the design variables become independent of the boundary element mesh in order to avoid the remeshing which was necessary in each iteration in the usual optimization procedures.An effective three dimensional boundary element method was developed for predicting electro-galvanic field response of a structure which consists of slender parts. Another effective method was developed to analyze the galvanic corrosion problems of a heat exchanger which had thousands of stainless pipes connected to the brass plate. The inverse problem where the density of the current across the metal surface was estimated from the potential values measured at some points far from the metal surface was solved by using the fuzzy set and boundary element method. The identification of coating defect in corrosion problems were also treated by usung the boundary element method. Less