The Application of Topological Gradients to Defect Identification in Magnetic Flux Leakage-Type NDT

An inverse problem is formulated to indentify the shape and size of the defects in a nonlinear ferromagnetic material using the signal profile from magnetic flux leakage-type NDT. This paper presents an efficient algorithm based on topological shape optimization which exploits the topological gradient to accelerate the process of shape optimization to identify the defect. Topological gradient images for the cracks are obtained using 2-D and 3-D finite element models. Robustness of this imaging method in the presence of noise is also evaluated.