Application of PZT-Based Piezoelectric Element for Vibration Measurement and Rotor Fault Detection

Unbalance in rotating machineries is always a critical concern to industry and involved a huge cost in sensing by sophisticated devices. A simple coin-type piezoelectric element is well known for its application in small-scale energy harnessing, although its potential to sense vibration for industrial application is not enough explored. In this work, a proof of concept is proposed to utilize bending mode vibration of PZT element to measure unbalance vibration within the frequency range of 20-100 Hz. A prototype model of a cantilevered circular PZT with added point masses at circumferential position is developed and calibrated by rigorous testing on electromagnetic exciter along with a standard accelerometer. Eventually, the device is tested for rap test and unbalance measurement of a rotor test rig. The robustness of the device is checked by measuring different severity levels of fault at different speed. Validation of the measured unbalance signal from 1100 to 2100 rpm indicated an accuracy of 94.44-99.39%. The results obtained show that by varying the position and magnitude of the added mass, the frequency range of the device can be altered for different applications.