Ferromagnetic Cylinders in Earth's Magnetic Field-a Two-Dimentional Model of Magnetization of Submarine

Abstract

For an optimal design of degaussing system of a submarine, a thorough understanding of magnetization of a submarine in the earth's magnetic field is required. As a prelude of three-dimensional modeling of a submarine, in this paper is presented an analysis of magnetization of a two-dimensional magnetizable cylinder placed in the earth's magnetic field. The cylinder is of infinite length and arbitrary cross section. It may be oriented in such a way that the earth's magnetic field is either perpendicular or parallel to its axis. The cylinder is made of steel which, in general, exhibits a nonlinear B-H characteristic. However, under the influence of the earth's magnetic field which is very weak, the permeability of the cylinder can be considered to be a constant. An integral equation is formulated for the unknown magnetization current on the surface of the cylinder. The integral equation is solved numerically employing a moment method solution technique. Based on knowledge of the magnetization current, the magnetic field produced by the cylinder is computed. Data of the magnetization current and the magnetic field are presented and discussed. To validate the computational method presented in this paper, the numerical results of the total magnetic field, as the sum of the earth's magnetic field and the magnetic field produced by the cylinder, are compared with the boundary condition requirements near the cylinder surface.