Analysis of the manufactured shape of rectangular THUNDER-type actuators

Abstract

This paper discusses the mechanical characteristics of laminated piezoelectric actuators that are manufactured at an elevated temperature, to cure the adhesive bonding the layers together, and then cooled to a service temperature. The actuators are of the unimorph-type, which are composed of a layer or layers of passive materials and a layer of piezoelectric material. THUNDER (thin layer unimorph ferroelectric driver and sensor)-type actuators, which consist of layers of metal, adhesive, and piezoelectric material, are studied and investigated in detail to understand the thermal effects due to the elevated manufacturing temperature. Owing to the large out-of-plane deformations of THUNDER-type actuators as a result of cooling to the service temperature, inclusion of geometric nonlinearities in the kinematic relations is taken into consideration for prediction of the thermally induced deformations and residual stresses. The deformations and residual stresses are predicted by using a 23-term Rayleigh–Ritz model and a finite-element model using ABAQUS. The thermally induced deformations result in actuator shapes which can be dome-like or near-cylindrical. Which shapes actually occur depends on the geometry of the actuator. Actuation responses of the actuators caused by a quasi-static electric field applied to the piezoelectric layer are also studied with the Rayleigh–Ritz approach. It is shown that geometric nonlinearities play an important role in the actuation responses, and these nonlinearities can be controlled by the choice of actuator geometry.

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