Experiment And Mechanism Research Of Magnetic Memory Under Different Stress States

In recent years,metal magnetic memory testing technique has been recognized by people and attracted a large number of scholars study on it.Because it can evaluate stress(or strain)state of ferromagnetic components quickly without surface treatment,and devices it required is cheap and portable.But the hidden behind physical mechanism is not perfect,so it is necessary to further study the basic theory of metal magnetic memory.In this paper,from the angle of unidirectional and plane stress state,based on the experimental results of magnetic memory during loading in two kinds of stress states.The improved J-A model under uniaxial stress and COMSOL software are used to simulate the magnetic field distribution on the surface of the specimen and the model under the two directional stress state Specifically,this paper has carried on the exploration and research from the following aspects:The magnetic memory test under uniaxial stress is carried out by static tensile test of Q235 steel bar specimen and plate specimen.The evolution law of magnetic memory signal during loading is recorded,The change law of the single point of the bar specimen with the loading process is obtained,and the change relation of the measured line with the load at the V notch is also discussed;By means of an improved compression test method,The static load test of Q235 steel is carried out,and the change law of magnetic memory signal in the process of loading is obtained.According to the effective field theory and the principle of proximity,the J-A model of magneto mechanical effect under uniaxial stress has been rearranged,The stress demagnetization term and the dependence of magnetic domain coupling coefficient on stress are added,and the theoretical model of magnetization varying with stress is re established,The simulation of magnetic signals under unidirectional stress condition is completed,and it is found that the improved model is closer to the experimental results than the original J-A model.At the same time,through the COMSOL software to simulate the distribution condition in static tension under the surface of magnetic signal plate V notch,extraction of magnetic signal distribution close to the V notch on the 2-D line,found consistent with experimental data.The torsion memory experiment of Q235 steel bar specimens and notched specimens was carried out,and the magnetic memory experiment under two directional stress condition was completed.Study on the magnetic signal changes during twisting,and Hugh Hart controlchart is introduced into the analysis of early diagnosis of injury of the magnetic memory signal to the quality management in the field of data,in order to eliminate the magnetic fluctuations caused physical phenomena to explain difficult interference,thus quantitative identification of early damage in the process of torsion.According to the state of torsional shear stress,Based on the stress state at the moment of twist,the shear stress is transformed into a normal stress perpendicular to each other,and a magneto mechanical effect model under the action of torque is established,The derived model and numerical simulation analysis,variation of the magnetization torque under the action of the magnetic signal that showed a downward trend after rising,consistent with the experimental results,which explain the basis for the reverse magnetic memory testing mechanism under stress.