Analysis of the manufactured shape of rectangular THUNDER-type actuators

Abstract

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