Comparing the Measurement Methods for Testing the Piezoelectric Ring Element in a Knock Sensor

The paper presents experimental research of the ring PZT ceramics that are used as the active element in knock sensors. The aim is to compare selected methods for determining the material coefficients, the pie-zoelectric charge coefficient d33 of an active toroidal PZT element in particular. In the research, we measured the material coefficients of an active ring PZT element to test some of the property detection approaches. Before being employed, each such ring element has to be checked in terms of its overall quality and functionality. The relevant procedure comprises several predefined stages, in-cluding verification of the geometry and material properties. In this context, the resonant frequency is measured to enable calculation of the effective electromechanical coefficient; the concrete values of the frequency and the coefficient enable us to partially assess the actual quality of the sample. This tech-nique, referred to as the frequency method, nevertheless cannot be used to determine the piezoelectric charge coefficient (d33) in the rings; for such a purpose, one of the direct charge determination techniques is regularly utilized. Advantageously, integrating both approaches generally allows us to characterize the applied piezoelement in a comprehensive manner, i.e., from the perspective of the resonant frequency stability in a ring and in terms of verifying the piezomaterial’s pa-rameters and polarization. The experiment relied on a set of Sonox P502-based rings by CeramTec. In these samples, we tested the resonant frequency stability via an Agilent 4294a impedance analyzer. Subsequently, we measured the rings with a d33 meter to determine the value of the charge on the electrodes that corre-sponds to the force applied to the sample. The entire experiment yields a comprehensive description of the involved methods for evaluating and verifying the quality and applicability of piezoelectric rings be-fore their use in knock sensors.

Keywords

Piezoelectric charge coefficient, d33 meter, frequency method, ring, knock sensor

Citation

Proceedings of the 29th International Congress on Sound and Vibration. 2023, p. 1-8.

Document version

Accepted version

Language of document

en

Document licence

Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International
http://creativecommons.org/licenses/by-nc-sa/4.0/