J-A-N Force Magnetic Coupling Mechanism Model under Multi Cycle Dynamic Cyclic Stresses
At present,force magnetic coupling J-A model did not consider the influences of do-main wall thickness and multi cycle dynamic cyclic stresses in pinning fields,which resulted in an overestimation of stress magnetization values in the J-A model that could not accurately describe early fatigue damages.Therefore,based on domain wall theory and Burgers dislocation theory,the domain wall thickness factor was introduced to improve the pinning field equation of the J-A model.Further-more,factors such as stress amplitude and cycle number of cyclic loads were considered,and a J-A-N force magnetic coupling mechanism model under multi cycle dynamic cyclic stress was established.Magnetization laws were obtained under different dynamic cyclic stress amplitudes σa and mean stressσm.With the same cycle times,the σa mainly affects the stress magnetization rate,while the static mean stress σm mainly affects the stress saturation magnetization size.When the same σm is constant,with the increase of σa,the speed of reaching stress saturation state increases.When the same σa is constant,the stress saturation magnetization decreases with the increase of σm.To verify the effective-ness of the J-A-N model,magnetic field signal detection experiments were conducted on 45 steel three-point bending specimens under multi cycle dynamic cyclic stress,and the experimental results are consistent with the model ones.
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