Enhancement of Particle Swarm Optimization Algorithms for the 3D Crack Reconstruction from ECT Signals

This paper presents some strategies to enhance the efficiency of Particle Swarm Optimization (PSO) algorithms applied for the three-dimensional reconstruction of cracks from eddy current testing (ECT) signals. A fast forward FEM-BEM solver using database was adopted to simulate the ECT signals due to cracks with parallelepiped shape for various lengths, widths and depths. The inverse problem is formulated as an optimization problem, aiming to minimize the distance between the signal due to of the real crack and the signal due to a potential solution (crack). A novel technique which combines the features of PSO and local search methods is used in the inversion of ECT signals. The local search methods are specific to such kind of inverse problems. The points used in the local search are chosen in order to avoid local minimum in PSO algorithms. Numerical results of the 3D reconstruction of cracks from simulated 2D signals are presented and discussed.