A finite element approach to model and analyze photostrictive optical actuators

Photostrictive materials, called PLZT, exhibit large photostriction under uniform illumination of high-energy light. These materials are of interest for future generation wireless remote control photo-actuators, micro-actuators, and micro-sensors applications. The photostrictive effect is a superposition phenomenon of bulk photovoltaic effect and converse piezoelectric effect.;In this present research photostrictive thin films are analyzed to evaluate their use as actuators in a future MEMS gyroscope. The finite element method is used for accurate analysis of photostrictive thin films. Four-node isoparametric quadrilateral plane stress elements are used to model photostrictive thin film and eight-node nonconforming brick elements are used to model a silicon wafer under the photostrictive thin film. A numerical finite element code, BAMAFEM, has been modified by introducing photostrictive material modeling capability. For generation of program code the FORTRAN90 language is used. Established analytical solutions have been used to verify the BAMAFEM finite element results.;Comparison of BAMAFEM results and MATLAB results of 2-D displacements indicate that BAMAFEM results almost match with the theoretical results. For the verification of the finite element formulation of the photostrictive element and the BAMAFEM program code, a steel simply supported beam with one PLZT actuator bonded on top of the beam is studied. The BAMAFEM result for transverse deflection matches the analytical result within a small difference (1.7%). Using the valid and verified modified BAMAFEM finite element program code, static analysis has been done to calculate transverse deflection for a silicon cantilever beam with a PLZT actuator bonded on the whole top surface of the beam. BAMAFEM output of transverse deflection matched the analytical result of the same with a percent error of 1%.