Numerical studies to signal characteristics with the metal magnetic memory-effect in plastically deformed samples

Metal magnetic memory (MMM) is a new non-destructive (NDT) method for inspecting the early damage of ferromagnetic structures using the residual magnetic field (RMF) signals. Our previous experimental research has confirmed that ferromagnetic materials exhibit various RMF features in different deformation stages. This paper presents a 2-Dimensional (2D) numerical study of RMF characteristics of ferromagnetic samples subject to the mechanical deformation. A new criterion is proposed to determine the plastic deformation. Then some parameters are defined to characterize the RMF signal. After that, the dependence of these parameters on the defect width, depth, location, testing position and direction are analyzed. This work is useful for promoting the MMM from a qualitative NDT technique to quantitative technique.