1992 Fiscal Year Final Research Report Summary
Optimization of Cathodic protection system by Boundary Element Method
| Project/Area Number |
03555014
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
機械材料工学
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
AOKI Shigeru Tokyo Institute of Technology Professor, 工学部, 教授 (90016436)
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| Co-Investigator(Kenkyū-buntansha) |
MIYASAKA Matsuho Ebara Research Co. Ltd. Chief Researcher, 流体研究所, 主任研究員
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| Project Period (FY) |
1991 – 1992
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| Keywords | Cathodic Protection / Optimum Design / Boundary Element Method / Sensitivity Analysis / Effective Method of Corrosion Analysis / Inverse Analysis / Fuzzy Set / Identification of Paint Defect |
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| Research Abstract |
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
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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
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