Electromechanical performance of structurally graded monolithic piezoelectric actuator

Abstract

In this paper, the effect of structural gradients in monolithic piezoelectric actuators is investigated. Different cross-section profiles were micro-machined with a laser into commercial PZT 5H bulk discs with thicknesses of 375 µm and 500 µm (∅ 25 mm). Profiles and curvatures of the actuators were measured which showed both concave and convex structures, thus indicating pre-stress of the actuators. After poling, the distribution of out-of-plane displacement was scanned by a fibre-optic laser vibrometer. Maximum displacements of ∼6.3 µm and ∼24.8 µm were obtained from a freely moving and clamped ∼375 µm thick actuator, respectively, in a ±0.5 V/µm electric field at 10 Hz frequency without load. Furthermore, deflection in the centre of the actuators was measured up to 184 mN load using the same electric field and frequency. Bending of the bulk actuators without any additional layer was a consequence of the gradient in poling and driving electric field via thickness variation of the material. Hence, different regions produced strain distribution and bending in a similar fashion to other benders. Actuators with the highest arch height exhibited the highest displacement and load bearing capabilities derived from the increased area moment of inertia and enhanced piezoelectric response due to pre-stress. The results show that the monolithic bending actuators can be realised by simple structural designing of the actuator. Such structural gradients can be one reason contributing to the higher displacement of RAINBOW actuators compared to other pre-stressed actuators. In a further development, the structural gradients can be utilized in high displacement pre-stressed actuators and in miniaturized monolithic piezoelectric devices.

Non-uniform electric field in poling of structurally graded monolithic piezoactuator

“…The applied voltage for each electric field was calculated according to the thinnest region of the actuator. The measurements were made with a Radiant RTV6000HVS system (Radiant technologies, [1,3,12]. Profiles of the actuators were measured again after measurements.…”

“…Utilizing the electric field gradient, bending actuators can be fabricated from bulk samples without any additional layer [1,2]. Displacement capabilities of recently developed structurally graded piezoelectric bending actuators can be improved further by optimisation of the poling process [3][4][5].…”

“…In this paper optimisation of the poling conditions for structurally graded piezoelectric actuators is studied by measuring the remanent polarisation and coercive electric field at different temperatures and electric fields. The results are compared with bulk and pre-stressed actuators, especially with RAINBOW actuators [1,3,10].…”

High performance thin film PZT ultrasonic transducer by CSD for distance measurements in water

“…The displacement as a function of frequency in the centre of the transducer was measured using fibre-optic laser vibrometer OFV-5000 (Polytec GmbH, Germany) and XY-table [5][6][7] with 1.25 Both in air and in water models were calculated. In the modelling, the 2D wireframe ( Fig.…”

High piezoelectric actuation response in graded Nd2O3 and ZrO2 doped BaTiO3 structures

“…Recently, functionally graded actuator systems have attracted much attention [14][15][16]. In this paper, fabrication of graded electromechanical actuators from Nd and Zr doped BT was explored.…”