科研之友
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摘要
In metal magnetic memory (MMM) detection, the Jiles-Atherton model describes material magnetization caused by the geomagnetic field and cyclic stress. However, characterization of the effects of fatigue damage on magnetization remains an issue. In this paper, an expression for magnetization intensity M-0 related to dislocation and plastic strain amplitude epsilon(p) was incorporated into a modified Jiles-Atherton model. To validate the M-0 expression, standard tensile fatigue tests were performed. Results indicate that the domain wall pinning parameter k(1) in M-0 is linear in both dislocation density rho and average dislocations slippage distance lambda, as is also the shear plastic strain amplitude in the stress control fatigue. The stress amplitude in strain control fatigue however is linear with respect to rho(1/2). Therefore, M-0 can be expressed as a function of stress and epsilon(p) (or (lambda) over bar and stress amplitude). Experiments showed that calculated M-0 variations in fatigue development processes can reflect a variation law in the MMM signal, with certain differences. There is a numerical difference between H-px and M-0 because the surface magnetic field is much weaker than that within the ferromagnetic material. H-px increases after macro crack initiation caused by an additional material demagnetization field and a leakage field near the crack during cracking.
