Large Stroke High Fidelity PZN-PT Single-Crystal “Stake” Actuator

摘要

A new piezoelectric actuator design, called “Stake” actuator, is proposed and demonstrated in this paper. As an example, the stake actuator is made of four -mode PZN-5.5%PT single crystals (SCs), each of 25 mm ( ) mm ( ) mm (T) in dimensions, bonded with the aid of polycarbonate edge guide-cum-stiffeners into a square-pipe configuration for improved bending and twisting strengths and capped with top and bottom pedestals made of 1.5-mm-thick anodized aluminum. The resultant stake actuator measured 9 mm mm mm. The hollow structure is a key design feature, which optimizes SC usage efficiency and lowers the overall cost of the actuator. The displacement–voltage responses, blocking forces, resonance characteristics of the fabricated stake actuator, as well as the load and temperature effects, are measured and discussed. Since is negative for [011]-poled SC, the “Stake” actuator contracts in the axial direction when a positive-polarity field is applied to the crystals. Biased drive is thus recommended when extensional displacement is desired. The SC stake actuator has negligible (<1%) hysteresis and a large linear strain range of >0.13% when driven up to +300 V (i.e., 0.75 kV/mm), which is close to the rhombohedral-to-orthorhombic transformation field ( ) of 0.85 kV/mm of the SC used. The stake actuator displays a stroke of (at +300 V) despite its small overall dimensions, and has a blocking force of 114 N. The SC stake actuator fabricated displays more than 30% larger axial strain than the state-of-the-art PZT stack actuators of comparable length as well as moderate blocking forces. Said actuators are thus ideal for applications when large displacements with simple open-loop control are preferred.