Measurement of piezoelectric ceramics using autocorrelation analysis to avoid history-dependent effects

Abstract

Piezoelectric materials often undergo material degradation with the application of severe stress. Consequently, repetitive testing with single samples can be very misleading if the interval between increasing stress levels is too small. In this paper, the autocorrelation analysis technique is used to determine a proper stress increment such that single sample testing is uncorrelated with previous stress exposure, consequently insuring an accurate material evaluation. Five piezoelectric materials were evaluated with electric field to 6.0 kV/cm and hydrostatic pressure to 34.5 MPa (5000 psi). Autocorrelation analysis of the data showed that electric field increments of 1.6 kV/cm and pressure increments of 5.5 MPa (800 psi) were adequate to guarantee valid results while minimizing the number of samples required. It is expected that this autocorrelation analysis technique can be used in other applications where successive measurements are being made and history-dependent behavior is suspected or known.