Performance Analysis And Mechanism Study Of SiC High Temperature Pressure Sensor Under Vibration Environment

With the development of science and technology,SiC high temperature pressure sensors are more and more widely used in the aerospace field.In recent years,researchers at home and abroad have begun to focus on the study of output characteristics and reliability of the sensors.However,the current research on the reliability of SiC high temperature pressure sensor is mainly concentrated on high temperature environment,and the stress of the vibration environment is less involved,and the influence of vibration environment stress on aerospace electronic equipment can not be ignored.Therefore,the performance analysis and mechanism research of SiC high temperature pressure sensor in vibration environment is of great significance to the development of sensor.Firstly,based on ANSYS Workbench and COMSOL software,the spectral analysis and time domain analysis simulation methods under three vibration modes of random vibration,sinusoidal vibration and shock vibration are analyzed for the characteristics of SiC capacitive high temperature pressure sensor.A method of transforming the vibration excitation signal between the frequency domain and the time domain is proposed.According to the established vibration simulation method,the vibration simulation of horizontal and vertical frequency domain excitation under the given test standard is carried out on the sensor structure model.Finally,the stress distribution and displacement response of the sensor under three vibration modes are obtained and compared.The results show that except for the sensitive components,the stress and displacement responses of the remaining components of the sensor structure under horizontal vibration excitation are greater than the vertical direction.Under the given standard,the impact has the greatest influence on the stress and displacement caused by the sensor structure.The maximum stress reaches 9.871×10⁷N/m² and the maximum displacement reaches 3.17?m.Therefore,the impact of shock vibration on the sensor is most obvious.The time domain vibration excitation analysis of the sensor is carried out,and the transformed time domain vibration excitation signal is loaded to obtain the stress distribution and displacement response of the sensor structure under random vibration and shock vibration.For the shock vibration mode,the conditions for determining the mechanical and electrical performance degradation of the sensor are clarified,and the maximum stress and displacement of the sensor under different impact amplitude shock vibrations are obtained.The curve of the maximum stress and displacement of the sensor as a function of the acceleration amplitude is fitted,and the critical mechanical performance degradation acceleration of each component in the horizontal and vertical directions is predicted according to the mechanical performance degradation determination condition.The critical mechanical performance degradation acceleration of the valve housing in the horizontal direction is at least 3.02×10⁴g,and the critical mechanical performance degradation acceleration of the SiO₂ insulating layer in the vertical direction is 1.74×10⁴ g.Aiming at the relationship between the mechanical degradation mechanism of the mechanical and electrical properties of the sensor,the impact excitation of the sensor is applied to the acceleration of the critical mechanical performance degradation of each component,and the displacement simulation result of the cavity part under each acceleration is obtained.According to the established equivalent capacitance,the model calculates the corresponding output capacitance.The calculation result is substituted into the electrical performance degradation determination condition to calculate the zero drift rate when the mechanical properties of the sensor components are degraded,and finally the electrical performance degradation determination is completed.The comprehensive mechanical and electrical performance degradation results show that the horizontal impact excitation has a great influence on the mechanical performance of the sensor,but the impact on the electrical performance of the sensor is weak;the vertical impact excitation has little effect on the mechanical performance of the sensor,but has obvious influence on the electrical performance.The effect of degradation of electrical performance is more serious than the degradation of mechanical properties.When the mechanical properties of some components of the sensor structure deteriorate,the sensor can still work,but when the electrical performance of the sensor deteriorates,the sensor will not work.