A numerical method for simulation of nonlinear eddy current testing signals based on transient A_r formulation

To explore the principle and to optimize the nonlinear Eddy Current Testing (ECT) system, a forward numerical analysis code for nonlinear ECT signal simulation is indispensable. In this paper, an edge element numerical code of the transient A_r (reduced A) formulation is developed for this purpose. The nonlinear feature of the permeability in each element is taken into account at every time step during step by step numerical integration procedure. The dependence of the third harmonic component of the response signals on the initial permeability is investigated by using the developed code. The qualitative agreement of the simulation and the experimental results demonstrated the feasibility of the proposed simulation method and the corresponding numerical code.