Residual magnetic field variation induced by applied magnetic field and cyclic tensile stress

摘要

Magnetic memory testing (MMT) method is a novel non-destructive testing technique due to its unique advantages of stress concentration identification and early damage detection for ferromagnetic materials. However, a thorough understanding of the impact of exciting magnetic source and cyclic stress on the residual magnetic field variation has not been clearly addressed. The surface magnetic memory signal H_p(y) induced by applied magnetic field and cyclic tensile stress was measured throughout the fatigue process. The correlation of H_p(y) and its gradient K changes with loading cycles and applied magnetic field intensity H reported. The results show that applied magnetic field can only change the magnitude of MMT signal instead of changing the H_p(y) curve's profile. The H_p(y) value increases with the increase of the H, and the if value is approximately linear to the H. The maximum gradient K_(max) indicating the degree of stress concentration increases with the increase of either stress cycles or H. The phenomenon was also discussed from the view of the magnetic dipole in a ferromagnet.