Flextensional 'moonie and cymbal' actuators

The moonie transducer consists of a piezoelectric or electrostrictive ceramic disc (either in single layer or multilayer form) sandwiched between two metal endcaps, each having a crescent shaped cavity on its inner surface. These metal endcaps serve as a mechanical transformer for converting and amplifying the lateral displacement of the ceramic into an axial motion of the endcaps. Both the d{dollar}sb{lcub}33{rcub}{dollar} and d{dollar}sb{lcub}31{rcub}{dollar} piezoelectric coefficients contribute to the axial displacement of the composite. The moonie transducer can be used as hydrophone, transceiver, or actuator.; The aim of the present work was to investigate the actuator characteristics of the moonie transducer. Important actuator properties including displacement, generative force, and response time were used to characterize the moonie actuator. An intensive investigation of the cavity size of the endcaps was carried out to understand their effect on the actuator characteristics of the moonie. Displacement increases exponentially with increasing cavity diameter and increases linearly with increasing cavity depth. Displacement is inversely proportional to the endcap thickness. Displacement and generative force show a position dependent behavior. The fastest response time of the moonie actuator varies between 5-50 {dollar}mu{dollar}sec depending on the cavity size.; As a part of this thesis a new endcap was developed. The new flextensional actuator was called the "Cymbal". The cavity of the cymbal endcap has a truncated conical shape. A punch and die were designed to fabricate identical endcaps with minimal cost. Cymbal actuators show higher displacement values approximately 40 {dollar}mu{dollar}m, for the dimensions evaluated in this study, with less position-dependent behavior. They also have higher generative forces (15 N) due to the enlarged active surface, and reduced metal content.; The reliability of the moonie actuator depends on the mechanical, electrical and chemical stability of the bonding layer. The characteristics of the bonding layer of the moonie actuator were tested with destructive (peel), and nondestructive (Scanning Acoustic Microscopy and resonance spectrum) techniques.; Outstanding actuator properties can easily be achieved with flextensional moonie and cymbal designs by changing the cavity size, endcap thickness, and endcap material. With its unique design, moonie actuators cover a wide performance range between multilayer and bimorph actuators.