Design,Manufacture And Testing Of High Temperature Resistant Surface Acoustic Wave Strain Sensor

Real-time in-situ acquisition of mechanical parameters of structural components such as aero-engine turbine blades is of great significance for early warning of mechanical accidents and evaluation of engine service life.Turbine blades are exposed to high temperature and harsh environments for a long time,and traditional strain sensors cannot monitor the condition of structural components for a long time due to the failure of solder joints.The surface acoustic wave sensor has shown important application value in this field because of its small size,strong anti-interference,simple installation and long-distance transmission.Lanthanum gallium silicate is a high temperature resistant piezoelectric crystal with good temperature stability,which is an ideal material for preparing high temperature resistant surface acoustic wave strain sensors.The main content of this article is:1.Starting from the structure and working principle of the surface acoustic wave device,the high temperature resistant surface acoustic wave strain sensor is designed from the aspects of device type,piezoelectric material,electrode material,interdigital transducer and parameters of the reflection grid.The strain sensitive mechanism of the strain sensor is analyzed.2.By establishing a three-dimensional model of a single interdigital period of the sensor,the positive and negative modal resonance frequencies of the sensor and the propagation speed of the acoustic wave are obtained by simulation;a high-sensitivity surface acoustic wave strain sensor structure is proposed,and the surface strain distribution of the structure is obtained.The optimal preparation parameters of the structure were determined by simulation analysis of sensitivity and sensitivity.The high temperature resistant SAW strain sensor was manufactured,and the wet etching process was explored for the proposed high sensitivity strain sensor structure.3.A temperature-strain composite test platform is built and the prepared sensor is tested.The sensor has been tested in the temperature range of 18-700℃ and the strain range of 0-500με.The test results show that the sensor still has reliable performance under the high temperature environment of 700℃,the sensitivity of the sensor is 20.09Hz/με,and the maximum relative error and hysteresis error are 3.35% and 6.98%,respectively.Aiming at the interference of temperature on strain test,a temperature-strain demodulation algorithm model is proposed.The demodulated strain value is basically the same as the reference strain value,and the maximum error is between-4.2% and 5.425%.