| In recent years,the rapid development of science and technology has put forward higher requirements on acceleration and vibration measurement technology.The sensor not only needs to be able to withstand higher temperatures,but also needs to have higher charge sensitivity.The development of high-temperature piezoelectric acceleration sensor is precisely the breakthrough meeting this requirement.In this paper,the piezoelectric acceleration sensor was optimized and designed based on the rotary cutting type.The normal temperature and high temperature characteristic tests show that the sensor has greater charge sensitivity.In this paper,CTGS crystal was selected as the piezoelectric sensitive material in the sensor design,and the shear structure design is adopted.Through the analysis of the working state of the shear sensor,it is determined that the mass M and the piezoelectric strain constant d are the main factors affecting the charge sensitivity of the sensor.Based on these two factors,the piezoelectric acceleration sensor is optimized and designed,a large mass M is obtained through the structural design of the sensor,and a large piezoelectric strain constant d is obtained by optimizing the CTGS crystal cut type.The overall structure of the sensor and various internal parts are designed to obtain a large mass M,and a signal output connector and signal transmission line suitable for high temperature environments are designed.Through numerical calculation,simulation and experimental verification,the cut type optimization selection of the piezoelectric sensitive material CTGS crystal is completed.As an anisotropic piezoelectric material,CTGS crystal has different piezoelectric strain constants under different cut types.Using the transformation law of the vector in the rotating space coordinate system,the changes of the piezoelectric strain constants in different Euler angle cuts and cuts at the maximum value of different positions are calculated from the three angles of single-angle variable,double-angle variable and triangular variable.Using the finite element simulation software COMSOL to model and simulate the calculation results,it is verified that the optimized cut type obtained by the numerical calculation can obtain more accumulated charges.After carefully analyzing the optimal cut type obtained by numerical calculation and simulation,the cut type with Euler angle(0°,90°,0°)was selected.After processing the designed sensor components and piezoelectric sensitive materials,they were assembled into a complete sensor and tested in a normal temperature and high temperature system.The test results at room temperature show that the average charge sensitivity is2.12p C/g,and the resonant frequency of the sensor is about 2.3k Hz.Compared with the sensor using LGS crystal with(0°,138.5°,26.6°)cut type,charge sensitivity has been significantly improved,and the lateral sensitivity is far less than the standard 5%.The test results at room temperature verify the correctness and feasibility of the optimized design.The test results at room temperature show that the resonance frequency of the sensor is about 2.2k Hz,and it shifts to the left as the temperature rises.When the vibration frequency is 100Hz to 1.1k Hz and the test temperature is from normal temperature to 600°C,sensor charge sensitivity increases first and then decreases and the average charge sensitivity of the sensor is 2.56p C/g,and it has high temperature stability.Based on the test results,a finite element simulation is performed on the resonant frequency of the sensor.The results show that the thickness,height and width of the center plate of the base have a great influence on the resonance frequency. |
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