パイプ形状を有する非軸対称3次元腐食問題の効率的な境界要素解析法

Abstract

An efficient numerical method is proposed for non-axisymmetric three-dimensional corrosion problems involving axisymmetric structures. The knowledge of physical quantities (potential and current density) on the surface of corroding materials is very important in corrosion monitoring and corrosion protection. Boundary element method is suitable for corrosion analysis, because it doesn't require discretization of internal elements. Although geometry of a structure is axisymmetric, enormous number of elements is necessary to discretize the realstructure, since surface physical quantities of the axisymmetric structure are affected by otherstructures and electrodes. To reduce the boundary elements, our method is based on complex Fourier series expansion of boundary quantities in circumferential direction of axisymmetricstructures. When axisymmetric structures depart from other structures and electrodes, this method has the advantage of decreasing the number of series, because surface physical quantities are more axisymmetric. In order to demonstrate the usefulness of the method, two example problems of buried pipelines in soil and a sea-water pump for cathodic protection system are presented.