| For space-based applications, NASA needs an alternative positioning and actuation system to replace heavy, inefficient electromechanical motors. Stress-biased piezoelectric Thunder actuators offer a possible alternative to electromechanical motors, but they are not sufficiently understood as to permit reliable predictions of their performance during device and mission lifetime. This work uses an equivalent electrical circuit analog based on a flat-plate resonator to model the fatigue and displacement behavior of stress-biased piezoelectric Thunder actuators. The functional parameters of temperature, actuator geometry, external load, drive voltage, and drive frequency are included in the model, which also accounts for fatigue effects on displacement response due to depolarization, domain pinning and micro-cracking. Results show that the modified 1-D flat-plate equivalent circuit model can predict adequately the experimental results obtained for both flat-plate devices and stress-biased Thunder devices. The model captures the resonance behavior observed at low external loading as well as the declamping associated with increasing drive frequency. The effects of fatigue on displacement response are also well predicted by this approach developed here, which should contribute to the increased utilization of these devices in a range of applications. |
