Using Modified J–A model in MMM detection at elastic stress stage

In order to propel the development of metal magnetic memory (MMM) technique in fatigue damage detection, a modified Jiles–Atherton (J–A) model is constructed to describe MMM mechanism in elastic stress stage. The MMM phenomenon is discussed from the view of energy minimum theory and equivalent magnetic field theory, the modified J–A model is constructed based on the energy balance in the process of magnetisation and the idea of J–A model, and the new model is used to simulate magnetomechanical effect by Matlab and compare with experimental results. It is shown that the forming process of MMM field is cyclic magnetisation in the range of equivalent magnetic field and the MMM field moves irreversibly towards a local equilibrium state . is the intermediate state with some pinning before M reaches the anhysteretic magnetisation state . The curve is a loop around the curve, and it changes with , H and the type of stress cycle. The modified J–A model that is suited for MMM detection is constructed by replacing in J–A model with and changing some parameters, and it can describe magnetisation features in tension, release processes better and explain the changes in the sign of that have been observed in experiments more reasonably. The modified J–A model can simulate the process of MMM field to become steady and the MMM field variation at fatigue process theoretically by changing model parameters, which is confirmed by experimental results. The results of theoretical research, simulation analysis and experiment verification all indicate that the modified J–A model can be used to describe MMM mechanism in elastic stress stage and analyse MMM field changes at fatigue process.

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