A Cylinder-Type Multimodal Traveling Wave Piezoelectric Actuator

Numerical and experimental investigations of a multimodal piezoelectric traveling wave actuator are presented. The actuator consists of a cylindrical stator with a conical hole and piezoceramic rings that are located at the node of the first longitudinal and second bending vibration modes; one piezoceramic ring is also placed at the bottom of the actuator. The actuator is clamped at the bottom using a special supporting cylinder and a ball bearing. Traveling-wave-type vibrations are excited at the top surface of the cylinder by employing a superposition of the first longitudinal and second bending vibration modes of the stator. The conical hole of the stator is used to amplify the vibration amplitudes of the contact surface. Four electric signals with phase difference of π/2 are used to drive the actuator. Numerical and experimental investigations showed that the proposed actuator is able to generate up to 115 RPM rotation speed at constant preload force.

A Matlab/Simulink 3D model of unsymmetrical ultrasonic sandwich transducers

Ultrasonic sandwich transducer is a half-wave resonant structure which oscillates in thickness direction. This paper presents a new Matlab/ Simulink model of a prestressed unsymmetrical ultrasonic sandwich transducer, which is modeled by applying three-dimensional (3D) Matlab/Simulink models of piezoceramic rings and metal endings derived from the piezoceramic ring model. With the cascade connection of the piezoceramic rings model with metal endings model, a complete model of ultrasonic transducer is obtained. Using this model one may determine any transducer transfer function, whereat is taken into the account the external medium influence, as well as the influence of the thickness and radial modes of each transducer component. The electromechanical equivalent circuit of the hammer transducer, which represents onedimensional (1D) model, is also derived and presented in this paper. The comparisons between experimental and theoretical results are quite good and validate the new analytical 3D design approach.

An Investigation of Piezoelectric Ring Benders and Their Potential for Actuating Servo Valves

This paper describes the deformation of a piezoceramic disc shaped actuator due to two effects: inner edge mechanical loading and electrical excitation. A 2D axisymmetric coupled-field finite element model was constructed to represent the piezoceramic ‘ring bender’. The model was used to predict actuator displacement due to a force applied to the inner edge, and also the piezoelectric induced strain due to an electric field applied in the poling direction of the piezoceramic. Results are compared with theoretical calculations of the deformation of a uniform thickness disc under mechanical load, and the displacement-voltage characteristics reported by the manufacturer. Experimental results for the displacement of the piezoelectric actuator, under a variety of constraint conditions, are also compared. The research presented provides an understanding of how the ring bender deforms under combined mechanical load and electric field. Each of these effects is considered and results show that the shape formed is different depending on whether the load is mechanical or electrical. This result provides an insight into how the actuator may be mounted for use as an actuator in servo valve pilot stage.