Magnto-Mechanical Properties Mechanism Of Metal Magnetic Memory Nondestructive Testing Technique

MMM(Metal Magnetic Memory)technique, a completely new technique based on inverse magneto elastic effect, has been paid extensive attention since its come out. It is very important to study MMM testing technique to improve MMM testing technique, to establish extensively applicable testing standard and enhance testing efficiency. The stress-susceptibility mechanism of MMM testing technique was comparatively systematicaly analyzed starting with both theory and experiment in this paper.Firstly, stress-magnetization vector describe equation in single Ferro magneto material was derived by using Lagrange multiplier method based on micro-magnetization theory, and stress-susceptibility variable formula was further studied. Taken a stripe Ferro magneto body as example, the stress -magnetization vector deflecting relationship was calculated by means of writing eight node isoparametric element calculation program on different working conditions ,stress-susceptibility curves in single Ferro magneto body was draw out. It was also attempted to extend the conclusion derived in single ferromagnetism to general ferromagnetic components.Secondly, a susceptibility measurement device was designed accorded to transformer principles, the relationship between load stress and susceptibility of different measuring angle were measured by the reference of home and abroad, which provided important experimental data for studying MMM mechanism.At last, the magneto-mechanical constitutive equation for general ferromagnetic component were derived by means of minimal energy principle base on magnetic and elastic basic theory. Moreover, stress-tensor suscepti- bility expression formula was derived, tensor susceptibility Mohr circle and principal susceptibility concept were put forward, the formula of principal susceptibility and principal susceptibility direction angle were given. In the end the theory result obtained by the derived formula and experiment result were compared. Studying result indicated that the established theory model was well coincident with the experimental value.Those works provided some useful reference for seeking MMM technique mechanism and potential methods for improving MMM technique.