"Piezo-Bow"- High displacement and high blocking force actuator

Bending type actuators providing high displacement (1 mm) with low blocking force (0.5 N) and the stack actuators providing low displacement (1 m) with high blocking force (1 kN) represent the extreme ends of the current piezoelectric actuation technology. In the intermediate range there is deficiency of the actuator designs that provide high displacement with high blocking force in the frequency range of few kilohertz. This study addresses this issue and describes an actuator design "Piezo-Bow which exhibits high displacement with high blocking force at low frequencies. The structure consist of a piezoelectric bar poled along the length with metal caps attached to the two major faces of the bar bounded by steel blocks. The piezoelectric bar is multilayered for operating at low voltages. The dimensions of the structure were optimized by FEM simulation in order to realize the resonance frequency near 2 kHz. It was observed that by changing the actuator parameters, cavity depth and cap thickness the resonance frequency can be shifted to desired frequency range. Based on the FEM analysis the optimized actuator design was fabricated. A PZT based composition corresponding to 0.98Pb(Zr 0.52 Ti 0.48 )O 3 +0.01Nb 2 O 5 + 0.01PbO was synthesized to fabricate the active actuation component. The fabricated actuator was characterized for impedance, piezoelectric constant and displacement. The experimental results were found to be consistent with the FEM analysis.