Finite element modeling of Piezoelectric sandwich structures

Abstract

This thesis addresses the fundamental limitation of piezoelectric actuators: their restricted displacement range, which typically does not exceed a few tens of micrometers. To overcome this drawback, the work focuses on the design, modeling, and validation of a new compliant amplification mechanism integrated the piezoelectric actuator with a sandwich structure.The research begins with a comprehensive literature review, tracing the historical evolution of amplification strategies from rigid-body mechanisms to modern compliant structures. The analysis highlights the growing need for reliable models capable of predicting coupled electromechanical behavior and guiding the design of advanced actuators.Building on this foundation, the thesis develops a multi-level methodology. Analytical models provide preliminary estimations of amplification ratios, while the finite element method (FEM) is employed as the central tool for detailed modeling and simulation. FEM simulations capture stress distribution, boundary effects, and electromechanical coupling, offering predictive and optimization capabilities beyond simplified analytical formulations.A prototype of the proposed amplification mechanism is fabricated and experimentally tested. The measurements validate the analytical and numerical results, confirming the ability of the mechanism to effectively amplify piezoelectric displacement. Special attention is devoted to an innovative model capable of converting the deformation of a piezoelectric sandwich actuator into the translational motion of a rod using a single actuator, without the need for pulsed excitation as commonly reported in the literature. This approach demonstrates the feasibility of continuous and precise linear actuation, paving the way for new applications in compact and high-performance actuation systems.The originality of this work lies in combining design, finite element modeling, and experimental validation into an integrated framework. Beyond its scientific contributions, the thesis opens technological perspectives for high-performance actuators in micro/nano-positioning, robotics, biomedical devices, aerospace systems, and precision optics. In conclusion, the research demonstrates that finite element modeling is not only a powerful analysis tool but also a driver of innovation for the development of compact, reliable, and efficient piezoelectric-based compliant amplification mechanisms.