Research Of Magnetization Model Induced By Stress Under The Geomagnetic Field

Unlike traditional testing methods, metal magnetic memory testing technology has the characters of portable equipment, the simple operation. It is a viable NDT method for early diagnosis, and is gradually used in fatigue research.The relationship between magnetization and stress during the magnetizing induced by stress is the key of the metal magnetic memory testing technology. This article began with the one-dimension tension experiment. Then the J-A magnetization model under stress was introduced to the research of magnetic memory testing technology according to the comparison of J-A model's theoretic curve and experimental curve of forces and magnetic signals. In order to use the theoretic model widely, according to the equivalent magnetic field of stress theory, anhysteretic magnetization theory and the law of approach, improve the J-A model from one-dimension stress condition to any kinds of stress condition by choosing the equivalent stress as the stress variable and neglecting the effect of volume strain energy. And the new model was approved by three-point bending test. Based on the new model, the conceptions of hysteresis loop, magnetization curve and magnetic susceptibility, which were induced by stress, were given according to magnetization theory of magnetic field. The correlation between fatigue circles and magnetic susceptibility of stress was given through magnetic curve and fatigue theory. By dividing the correlation curve into three stages, compared with the three stages of fatigue, a method to detest fatigue damage and predict the life of fatigue. At the last, the method was approved to be correct and feasible by fatigue experiments.