Finite Element Analysis of Rainbow Ceramics

The finite element method has been utilized to analyze the processing and performance of the newly developed Rainbow (Reduced And INternally Biased Oxide Wafer) ceramic actuators. A Rainbow is produced by a special chemical reduction process to form a dome-shaped, stress-biased structure which delivers a large field-induced displacement while attaining moderate load-bearing capability. The creation of the domed structure and accompanying internal stress by the reduction process is simulated by considering a Rainbow as a two-layer heterogeneous circular plate and allowing it to cool down from the reduction temperature to room temperature. Based on the derived domed structure, the Rainbow performance including electric field-induced displacements and resonant characteristics is modeled. Modeled dome curvature, internal stress, and electromechanical characteristics of the Rainbow ceramic are discussed with respect to material properties and geometrical parameters. Comparisons between the modeling results and the experimental data obtained from the Rainbow samples made with PLZT ceramics are presented. A good agreement was exhibited between the modeling predictions and the experimental measurements for the dome curvature and internal stress distribution, but appreciable disparities were observed in the electromechanical properties. The results imply that the internal stress should have a strong influence on the Rainbow's electromechanical performance.