Research On Impedance Property Of Coil Based On Semi Conductive Composite

There are narrow curved surface layer structures in some military and civilian industrial equipment.The curved surfaces produce relative displacement in motion.The displacement and pressure between the curved surfaces need be measured to ensure the safety of the system.But the traditional rigid sensors cannot satisfy the requirement due to the narrow gap between the curved surfaces.Meanwhile,the existing eddy current sensor can only measure the non-contact displacement and cannot measure the pressure;the existing pressure sensor can only measure the pressure and cannot measure the non-contact displacement.In order to solve this problem,a kind of planar eddy current sensor based on semi conductive composite is designed.It can be affixed to the irregular surface softly to complete the curved surface displacement and pressure measurement.The major works are summarized as follows:(1)The COMSOL software is applied to simulate the eddy current coil.After the simulation,the experiments are carried out with the composite coils and compared with the simulation results.Then the influence of inner diameter,outer diameter,thickness and number of turns on coil performance is analyzed.(2)Complete the preparation of composite coils(mass ratio:0.04,0.08,0.12,0.16)and the construction of experimental platform.(3)The impedance properties of composite coils including impedance lift-off properties and impedance pressure properties have been studied.According to the experimental results,the effects of mass ratio and frequency on the impedance pressure and impedance lift-off properties of the composite coils have been analyzed.When the object is 45#steel or the composite film,the relative sensitivity of the impedance modulus of the composite coil whose mass ratio is 0.16 measuring the displacement and pressure at the 1MHz frequency is larger;the relative sensitivity of the impedance angle of the composite coil whose mass ratio is 0.16 measuring the displacement and pressure at the 100kHz frequency is larger.(4)The impedance lift-off properties and impedance pressure properties of the composite coils with different conductive phases have been analyzed.When the displacement and pressure is measured,the relative sensitivity of the composite coil whose conductive phase is carbon nanotube is obviously greater than the relative sensitivity of the composite coil whose conductive phase is grapheme.(5)The displacement and pressure measurement system is designed,including hardware circuit design and PC design.STM32F103VCT6 is used as the core processor of the hardware circuit which uses AD5933 to measure impedance.The PC which realizes the preservation and display of the data is written by Lab VIEW.(6)The displacement measurement ranges from 0-3mm and the pressure measurement ranges from 0-110N.According to the calculation results,the relative error is less than 9%.