Simulation Optimization Design And Experimental Study On Sensitivity Control Of Magnetic Field Sensor With Laminated Multiferroic Structure

Currently,only superconducting quantum interferometers can be used to detect weak magnetic signals,especially in the detection of biological magnetic signals,such as brain magnetic signals and cardiac magnetic signals.The magnetoelectric composite material which is composed of the magnetostrictive material and the piezoelectric material can freely convert energy between the magnetic field and the electric field,so the magnetoelectric composite material is able to apply in the design of weak magnetic field sensors.And related research has become a hot topic in academia and industry.Generally speaking,when the selection of materials,structural configuration,and size of the magnetoelectric composite structure are different,the sensitivity of the prepared magnetoelectric sensor will also be different.Once the magnetoelectric composite structure is prepared as a sensor,its sensitivity is usually fixed and will not change.Considering the need for a wide range of weak magnetic field sensors,for example,the measurement range needs to span from f T to n T,and even to u T.So,if the sensitivity of the sensor can be adjusted,it will be very beneficial to its wide range design and external signal acquisition and processing circuit design.To this end,this dissertation will focus on the nonlinear magnetoelectric coupling effect of the laminated magnetoelectric structure under the multi-physical fields,establish a nonlinear magnetoelectric coupling simulation calculation model under the multi-physical fields,and analyze the factors that affect the magnetoelectric coupling effect.And this thesis also explores the feasibility of numerical analysis and experimental testing to adjust the sensitivity of the magnetoelectric sensor by DC voltage generating pre-stress.The main contents are as follows:Firstly,this thesis analyzes the magnetoelectric effect in the laminated magnetoelectric structure,establish a bi-layer numerical simulation model and compare the simulation result with experimental data to verify the reliability of the model.And the magnetoelectric response of different magnetostrictive materials is analyzed.At the same time,the change of the magnetoelectric coefficient of the multilayer magnetoelectric structure,the magnetoelectric response of different configurations and the magnetoelectric response under different mechanical boundary conditions are studied.The results show that:(1)The initial susceptibility of the magnetic material has a great influence on the magnetoelectric re sponse.The magnetoelectric response of Metglas with an initial susceptibility of 1600 is 5 times larger than that of Ni with an initial susceptibility of 39 under the same conditions;(2)The maximum difference of magnetoelectric coefficient under different mechanical boundary conditions can be more than 200 times.Secondly,a strongly nonlinear fully coupled finite element model considering multiphysical coupling effect of laminated magnetoelectric structure is established by combining the nonlinear constitutive relationship of magnetostrictive materials and the linear piezoelectric constitutive relation.The nonlinear magnetization relationship of the magnetostrictive material is calculated by MATLAB.And the experimental data can agree well with the simulation result.At the same time,the non-uniformity of the internal field of the magnetoelectric material is analyzed,and the influence of different piezoelectric materials on magnetoelectric coefficie nt is calculated and analyzed.In addition,this thesis explores the regulation effect of pre-stress on magnetoelectric effect under different volume ratios.The simulation results show: the piezoelectric coefficient greatly influences the magnetoelectric coupling coefficient,and it is feasible to adjust the sensitivity of the magnetoelectric sensor by bias voltage generating pre-stress.Finally,this thesis proposes a method for adjusting the sensitivity of the magnetic field sensor of the magnetoelectric composite structure by applying an external excitation voltage.And the magnetoelectric response characteristics of the tri-layer magnetoelectric composite structure magnetoelectric sensor under different voltages are measured by experiment.The measurement results show that whether in the static or in the resonance,it can effectively adjust the sensitivity of the magnetoelectric sensorby changing the regulation voltage of the piezoelectric regulation layer.In different resonance states and different DC magnetic field segments,the trend of the sensitivity change is also different,especially in the first-order bending resonance mode with a resonance frequen cy of 43 k Hz,the sensitivity of the sensor changes by up to 47.59% within the range of 400 V in the regulation voltage.Experimental measurement results confirm the feasibility of externally regulating voltage to adjust the sensitivity of magnetoelectric sensor.