Abstract
A novel exciting method for a sandwich type piezoelectric transducer operating in longitudinal-bending hybrid vibration modes is proposed and discussed, in which the piezoelectric elements for the excitations of the longitudinal and bending vibrations share the same axial location, but correspond to different partitions. Whole-piece type piezoelectric plates with three separated partitions are used, in which the center partitions generate the first longitudinal vibration, while the upper and lower partitions produce the second bending vibration. Detailed comparisons between the proposed exciting method and the traditional one were accomplished by finite element method (FEM) calculations, which were further verified by experiments. Compared with the traditional exciting method using independent longitudinal ceramics and bending ceramics, the proposed method achieves higher electromechanical coupling factors and larger vibration amplitudes, especially for the bending vibration mode. This novel exciting method for longitudinal-bending hybrid vibrations has not changed the structural dimensions of the sandwich transducer, but markedly improves the mechanical output ability, which makes it very helpful and meaningful in designing new piezoelectric actuators operated in longitudinal-bending hybrid vibration modes.
Highlights
Piezoelectric ultrasonic actuators (PUAs) have been seen as an important and preferential type of element for precision driving due to their merits of simple structure, small size, quick response, high resolution and a lack of electromagnetic radiation [1,2,3,4]
PUAs with the sandwich transducer structure have been proposed and discussed by some previous researchers, where the longitudinal vibration was used to produce the driving force, whereas the bending vibration served the role of overcoming preload
Zhang et al designed a multi-degree of freedom (DOF) PUA under the operating principle of a longitudinal and bending vibrations hybrid, which was used to drive a robot finger joint [13]
Summary
Piezoelectric ultrasonic actuators (PUAs) have been seen as an important and preferential type of element for precision driving due to their merits of simple structure, small size, quick response, high resolution and a lack of electromagnetic radiation [1,2,3,4]. Lee et al tested an ultra-precision XY stage using longitudinal-bending hybrid bolt-clamped PUAs, in which the second longitudinal and eighth bending vibrations of a sandwich transducer were used to generate elliptical movement of the driving tip; their prototype achieved accuracy at the nanometer level [15]. All these works used sandwich transducers operating in longitudinal-bending hybrid modes, which meant that these two types of vibrations were generated simultaneously under the same frequency. Two sandwich transducers using the new and traditional exciting methods respectively were fabricated and measured
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