Simulation and Design of Piezoelectric Shape Morphing Geometries

Shape morphing materials have wide ranging applications, from microelectronics to aerospace. Applications abound further with electrically actuated, fast acting shape morphing materials. While much research has explored the shape morphing characteristics of a variety of materials actuated by thermal and chemical stimuli, our research focuses on the properties of piezoelectric materials. Shape morphing behavior is deconstructed to its most elemental form – material with a single dimension of curvature – such that a one unit, one directional model can be patterned in an extensive matrix to control an extended body’s shape in two dimensions. Taking results from a series of geometric parametric analyses conducted using finite element analysis in ANSYS with the piezoelectric and MEMS toolbox, a high curvature physically feasible model was developed with a minimum radius of curvature less than one meter in a single direction. A manufacturing method for this high curvature method is also proposed. Considering the low material stiffness of the proposed geometry, “pseudo-stiffness,” negating strains from external pressures stresses generated through the piezoelectric effect, was also explored. Correlating curvatures from pressures to voltages, a model was generated that could successfully counter transverse loads. Expanding the model to produce curvatures about 2 orthogonal axes, two methods were explored – shape-morphability in 2D in a multi-layer single unit, with layers polarized in different orientations, and that in an array of 1D units. With the former, a “saddle” shape was observed under corresponding electric field application and a “bowl” shape was difficult to obtain. In the latter model, even smaller radii of curvature than the unidirectional model were observed for a “saddle” shape, and radii of curvature less than a meter but larger than the unidirectional model were observed for a “bowl” shape. These geometries could be further patterned to explore a full range of shape morphability.