Effect of Large‐Amplitude Static and Dynamic Stress on the Mechanical Loss of Lead Zirconate Titanate Transducer Ceramic

The effect of static and dynamic stress on the mechanical loss of a piezoelectric ceramic has been measured. Static stress was applied pneumatically along the axis of a radially polarized tube of lead zirconate titanate measuring 2.54 cm long by 0.317 cm wall thickness. It was found that immediately after applying a static compressive stress of 3000 psi, the mechanical loss, proportional to the reciprocal mechanical quality factor Qm−1 increased from 1.27×10−3 to 4.54×10−3. The mechanical loss of the ceramic was determined by measuring the Q factor of the ceramic and its support, and correcting for the support losses. A similar tube was statically biased with a stress bolt by incorporating the tube as the active element in a small model transducer. The transducer was then coupled to a high‐power ultrasonic driver by means of which large dynamic stresses were generated in the ceramic. A dynamic stress of 3000‐psi peak was superposed on a static biasing stress estimated at 5000 to 10 000 psi. The bias alone...