Development of a Piezoelectric Accelerometer in High-impact Testing

摘要

A piezoelectric accelerometer is a sensor which can convert mechanical energy to electric charge and can be used to measure shock and linear acceleration in high-impact testing. In this paper, a piezoelectric accelerometer was developed with piezoelectric ceramics to measure acceleration in high-impact testing. Based on its working principle, mechanical model of the accelerometer was established, and the main factors influencing on the frequency response were analyzed. Two kinds of sensors with the same structure sizes were developed. The first kind of sensor used quartz crystal as piezoelectric material, and piezoelectric ceramics were adopted in the second kind of sensor. The frequency response test reslults of the two kinds of sensors shew that the first kind of sensor's frequency response was 8,000 Hertz, and the second kind of sensor's frequency response was 12,000 Hertz, which indicates that there were other factors influencing on the frequency response except for the structure size. So we can take some measures to improve the sensor's frequency response, such as adjusting the stiffness of the sensors with contact stiffness or selecting different piezoelectric materials. In this paper, the second kind of sensors with piezoelectric ceramics were detailedly analyzed and measured. With the nonlinear transient dynamics finite element analysis sofeware Msc.dytran, the dynamic stresses of the sensor fixed on a measured object which impacted a steel plate in high speed was simulated. The results indicate that the sensor has a measurement range of 60,000g. In a high-impact laboratory, 30 sensors were measured and found that their linearity was below 10%, and sensitivity was from 0.3 pC/g to 0.4 pC/g in the measurement range of 60,000g. In order to testify the sensor's anti-impact ability, a high-impact test was designed, in which the measured object impacted a steel plate with a velocity of 400 m/s and the acceleration measured with the sensor was recorded in a data recorder. The data indicates that the sensor can measure acceleration of 50,000g in high-impact environment.