Signal Analysis of Metal Magnetic Memory Under Residual Magnetic Field

Metal magnetic memory (MMM) testing is widely used to detect stress concentration in ferromagnetic materials, while residual magnetic field (RMF) will affect the results of MMM testing. Therefore, to improve the performance of MMM testing, analyzing the signals of MMM under RMF is essential. In this article, the signals of MMM were analyzed under different strength and direction of RMF. First, the magneto-mechanical coupled model considering RMF was established based on equivalent magnetic field theory. Then, the finite element (FE) model of MMM testing was developed, and the signals of MMM under RMFs were analyzed by FE model. FE and experimental results showed that the signals of MMM would be enhanced due to RMF, and whose shape would be affected by the direction variation of RMF. The normal ( $${H}_{x}$$ ) and tangential ( $${H}_{y}$$ ) components of signals would start to be inverted when the directional angle of RMF is 45°. In addition, the effect of RMF on signals of MMM was described by numerical method. Accordingly, the studies in this article will offer a reference for the inversion of stress concentration in MMM testing field.