Research On Frequency Characteristics And High Temperature Performance Optimization Of Piezoelectric Acceleration Sensor

As one of the pillars of modern information technology,sensor technology has made great progress with the development of science and technology,but it has also been put forward higher requirements.As a device that can detect the vibration of components,the acceleration sensor has attracted the attention of researchers.Piezoelectric acceleration sensor has the advantages of simple structure,small size,easy installation,and wide operating temperature range.After selecting specific materials,it can be applied to vibration measurement at high temperature,so it is widely used in various high-temperature vibration detection fields.This thesis studies the frequency characteristics of the shear piezoelectric acceleration sensor,discusses the influence of the sensor structure on the natural frequency,prepares and optimizes the piezoelectric acceleration sensor at room temperature and high temperature,and conducts room temperature and high temperature tests.In this thesis,the finite element simulation of the influence of the size of each part on the natural frequency of the sensor is carried out for the shear piezoelectric acceleration sensor with two-mass and three-mass structures,and it is found that the size of the central pillar and the mass has the greatest influence on the natural frequency of the sensor,but due to the limitations of sensitivity and other aspects,it is also necessary to choose a choice.A theoretical calculation method for the natural frequency of the triangular pillar structure sensor is proposed,and the calculation results of the model are basically consistent with the finite element simulation results.The study found that the symmetrical shear piezoelectric accelerometers using the central pillar have commonality in terms of structural influence on the natural frequency.Although the specific influence levels are different,the trends are similar,and they can be used for reference in design.The influence of sensor base shape and fixing method on the natural frequency of sensor installation is discussed,and it is found that the installation method with a circular base and a larger bottom fixing surface is better.Hard armored wires used for high temperature testing have little effect on the sensor’s natural frequency.Based on the finite element simulation and theoretical calculation results,this thesis uses CTGS piezoelectric crystals with tangential directions of(0~o,90~o,0~o)and stainless steel 316L materials to make a variety of shear piezoelectric acceleration sensors,and conducted room temperature tests on a variety of sensors,The working waveform of the sensor at each frequency point of a variety of sensors is normal;at the same frequency point,different accelerations have a linear relationship with the charge sensitivity,and the sensor works normally and stably.It was found that the resonant frequency of the two-mass sensor was about 3200Hz,and the charge sensitivity was about 0.7p C/g.The test found that the weight of the cover had no effect on the natural frequency.The resonant frequency of the triangular pillar sensor is about 6000Hz,and the charge sensitivity is about 1p C/g.Compared with the sensor of the same size made of aluminum alloy material,the performance has been greatly improved in many aspects,indicating that the elastic modulus of the material has a great influence on the natural frequency of the sensor.The size of the central pillar of the triangular pillar sensor is optimized.After optimization,the resonance frequency of the sensor is about 7200Hz,and the charge sensitivity is about1.6p C/g,achieving an increase of about 20%in resonance frequency.In this paper,a high-temperature test system was built using a T-shaped high-temperature bracket,and the test results of the two-mass sensor with and without a high-temperature bracket were compared at room temperature,and the feasibility of the high-temperature test method was verified by comparison.In the preliminary exploration of the high temperature application of the sensor,it reflects the high temperature stability of the sensor to a certain extent.The high temperature resistant design of the two-mass sensor was optimized,and the test was carried out at intervals of 200°C from room temperature to 800°C after high temperature annealing.After high-temperature annealing,the performance of the sensor is lower than that of the two-mass block at room temperature,the charge sensitivity is about 0.4p C/g,and the resonance frequency is about2100Hz,but the working state is stable,and the relationship with the acceleration is also linear.At 600°C,the charge sensitivity changed slightly,from 0.4p C/g to 0.2p C/g,and the charge sensitivity was stable at other temperatures.The resonant frequency does not change significantly in the high temperature environment,and the working condition of the sensor is also normal.