Surface deformation by piezoelectric actuator: from Park and Agrawal models to a simplified model formulation

Unimorph design consisting of a piezoceramic bonded to an elastic surface is the most common structure used to induce deformations. The analytic models developed by Park and Agrawal are extensively used to determine the induced strain on piezo-actuated surfaces. These models are based on different strain distribution hypothesis that, however, do not consider the relative thickness size between piezo and surface. Results using Park and Agrawal models are first compared with a finite element simulation, revealing how the piezo strain distribution considered by each model affects its prediction. Following, a simplified model suitable to be used in a preliminary design approach is proposed. This model allows an initial device dimensioning, also estimating the stresses involved. An experimental prototype matching a clamped surface actuated by a piezoceramic characterizes the piezo performance under practical conditions. The paper concludes with a detailed analysis of the validity of the proposed simplified model, comparing them with Park and Agrawal models, the FEM model, and the experimental results. © 2004 Elsevier B.V. All rights reserved.