The Sensitivity Improvement Method And Experimental Study Of Magnetostrictive Sensor

Magnetostrictive sensors are a new type of wireless passive sensors established based on the magnetostrictive effect.After nearly three decades of development,magnetostrictive sensors have been widely used in several disciplines.However,with the rapid development of technology,miniaturization,integration,multi-target,and high sensitivity have become the primary goals of sensor development.However,the development of magnetostrictive sensors is currently limited by factors such as the production process and processing cost of its core sensing element materials,and less research has been conducted on sensitivity enhancement,and the lack of corresponding design theories prevents the full potential of magnetostrictive sensors in multiple fields of application.Based on the above problems,this paper presents a series of studies on the sensitivity enhancement methods of magnetostrictive sensors from the perspectives of sensing element shape,substrate structure and detection system to further improve the performance of existing magnetostrictive sensors.Firstly,we analyze the principle of wireless detection based on the basic theory of magnetostrictive effect for the traditional magnetostrictive resonant sensor;we analyze the main factors affecting the sensitivity performance of the resonant sensor and propose a sensitivity enhancement method based on the optimization of the shape of the sensing element of the magnetostrictive sensor;we apply the optimization design theory to obtain the structure of the hourglass resonant sensor and use the ANSYS finite element method to study the sensitivity of the traditional resonant sensor and the hourglass resonant sensor.The resonant frequency expression of magnetostrictive sensor is given under the consideration of nonlinear effects,and the nonlinear magnetoelastic coupling vibration equation of sensor force in magnetic field is derived.At the same time,the equivalent circuit model corresponding to the sensor output is established,and the output characteristics of the signal are theoretically derived.Secondly,based on the working principle of the conventional magnetostrictive piezomagnetic sensor,the relationship equation of the machine-magnetic coupling model is established.From the base structure of the piezomagnetic sensor,the sensitivity enhancement method of the magnetostrictive sensor based on the optimization of the negative Poisson's ratio base structure is proposed;the structural characteristics of the negative Poisson's ratio base are analyzed,and the influence of the equivalent elastic parameters of the inner concave honeycomb structure on the tensile-compressive deformation is studied;the structural model of the negative Poisson's ratio base piezomagnetic sensor is proposed,and the influence of the negative Poisson's ratio structural parameters on the sensitivity of the piezomagnetic sensor is analyzed theoretically.The structural model of the negative Poisson's ratio matrix piezomagnetic sensor is proposed,and the influence of the negative Poisson's ratio structural parameters on the sensitivity of the piezomagnetic sensor is analyzed theoretically,and the relationship between the structural parameters of the matrix and the sensitivity is analyzed by ANSYS static simulation.In addition,from the perspective of the detection system,theoretical models of excitation magnetic field,bias magnetic field and detection coil are established,and the effect of the variation of excitation magnetic field,bias magnetic field and detection coil on the sensitivity of the magnetostrictive sensor in the detection system is simulated and analyzed by COMSOL multi-physics field simulation software.Finally,in order to verify the effectiveness of the proposed sensitivity enhancement methods,an experimental platform for magnetostrictive sensor performance testing is built,including a mechanical loading experimental platform,an output signal detection system and a sensor sensitivity test system.At the same time,the magnetostrictive sensor output performance testing experiments are carried out on this platform to verify the effect of the proposed sensing element shape optimization,negative Poisson's ratio matrix structure optimization and detection system parameters on the sensor sensitivity performance.The experimental results show that the sensitivity enhancement methods proposed in this paper can effectively improve the sensitivity of magnetostrictive sensors.