Electrical impedance tomography in the testing of material defects

The paper describes using electrical impedance tomography in non-destructive material testing. Under certain Neumann and Dirichlet boundary conditions, the forward EIT computation yields an estimation of the electric potential field in the interior of the volume. The FEM, in 2D or 3D, is exploited for the forward problem with current sources. Image reconstruction in EIT is an inverse problem, usually presented as minimizing a suitable objective function. To minimize this function, we can use the deterministic approach based on the method of least squares. Due to the ill-posed character of the problem, a regularization procedure, such as that embodied in standard Tikhonov regularization, has to be used. Electrical impedance tomography is a widely employed approach with numerous applications in, for example, physics and biology. As regards the former discipline, geophysical imaging is utilized in both searching underground conducting fluid columns near the surface and obtaining information about rock porosity or fracture formation. Other applications of EIT include the non-destructive testing and identification of material defects such as cracks or the identification of corrosion in materials.