ABSTRACT
Heat generation in piezoelectric materials originates from three losses, namely, dielectric, elastic, and piezoelectric losses. While the observed polarization vs. electric field curve draws sharp hysteresis edge around the maximum (and minimum) electric field, the complex parameter representation with dissipation factor tangents in this book reveals a narrow elliptic shape (counterclockwise locus!) with rounded edges. Though this discrepancy implies the modeling inaccuracy, we adopt the complex parameter method for the loss analysis merely from the mathematical simplicity viewpoint. We discuss the heat generation mechanisms of piezoelectric actuators under (1) the off-resonance operation for actuator applications (under a large electric field, 1 kV/mm or higher) and (2) the resonance (or antiresonance) operation for ultrasonic transducer applications (under a high-vibration condition at low-electric field, 100 V/mm or lower). Heat generation at off-resonance is attributed mainly to intensive dielectric loss tan δ′, while the heat generation at resonance is mainly originated from the intensive elastic loss tanϕ′.
