Proposal of Electromagnetic Inspection of Opposite Side Defect in Steel Using 3-D Nonlinear FEM Taking Account of Minor Loop and Residual Magnetism

The nondestructive evaluation of the opposite side defects of the steel wall in the petrochemical plant is necessary for safe maintenance. Generally, the alternating magnetic flux leakage testing (AMT) is used for detecting only the surface defect of the steel wall. In this paper, electromagnetic nondestructive inspection method for the detecting of the opposite side defect in the steel plate using this AMT method by applying the residual magnetism is investigated. The synthetic magnetic field of both residual magnetism and alternating magnetic field is estimated by the 3-D nonlinear finite element method taking account of the hysteresis and minor loop characteristics of the steel plate.