Reconstruction of cracks with physical closure from signals of eddy current testing

In this paper, a method for reconstruction of cracks with faces in physical contact (closures) is proposed by using signals of eddy current testing (ECT). Based on an idealized crack model, a database used forward approach is extended at first to enable the rapid simulation of ECT signals due to the closed crack. An algorithm in the conjugate gradient method category is introduced then for tackling inversion of crack parameters in different types (e.g. coordinates and conductivity). A code involving reconstruction of square cracks is developed based on the proposed scheme and be adopted to the reconstruction of several typical problems. The acceptable accuracy and high robustness shown in these examples verified the validity of the proposed strategy.