Frequency analysis of the Acoustic Emission signals from PZT ceramics during the application of ac fields

Frequency analysis of Acoustic Emission signals in the range of 100-1200 kHz obtained from PZT ceramics during the application of limited and continuous cycles of ac field was undertaken to understand the fatigue behaviour of these ceramics. In the limited cycles experimentation, lower higher range of frequency components fields (200 - 900 kHz) and higher fields yielded lower range of frequency components (200 - 500 kHz) at differnt temperatures of 60 degrees C and 160 degrees C. During continuous application of ac field, the initial stages of application yielded higher frequency components (100 - 850 kHz) and with increasing time of application, the frequency components of acoustic emission signal shifted towards lower frequency (less than 400 kHz). Electrical discharge induced cracking, resulted in the emission of frequency components in the range of 100 - 275 kHz.