High-temperature shear-type vibration sensor based on langasite piezoelectric crystal.

As aero-engines operate under extreme conditions such as high temperatures and speeds, the effectiveness of the engine tends to decrease. Therefore, real-time vibration monitoring of such structures is essential to ensure flight safety. However, the sensors used in the control system are prone to interference, thus leading to ineffective monitoring and eventually reducing the service life of the equipment. Therefore, in this study, a shear vibration sensor for real-time structural monitoring at 750 °C is designed and produced using a Langasite (LGS) crystal. Further, the high-temperature performance of the sensor is examined in the frequency, acceleration, and temperature ranges of 80-1000 Hz, 0.5-5g, and 30-750 °C, respectively. Its linearity is less than 1 %, which meets the application requirements of high-temperature piezoelectric vibration sensors. The average sensitivity of the sensor over the entire temperature range is 0.074 V/g. The sensor has good viability and can be used for testing in high-temperature environment applications as the sensitivity fluctuates by less than 2 % at different temperature points when applied to the same frequency. Furthermore, a temperature-vibration cross-decoupling approach is proposed to determine the acceleration value following temperature demodulation. The highest inaccuracy with respect to the reference acceleration is 4.54 %. Sensors also have a small size, are easy to install, and can maintain high reliability in harsh environments, playing an essential role in health assessment, fault prediction, and diagnosis of engines and other components. Therefore, the developed LGS acceleration sensor offers a promising alternative for real-time monitoring of structures in high-temperature environments, including aero-engines.