Simultaneous optimisation of orientation and constituent volume in piezoelectric composites

Piezoelectric composites are optimised for maximum strain levels by simultaneously accounting for the concentration and orientation of the piezoelectric and polymer constituents. Existing studies in piezoelectric composites are confined to independently identifying either the optimal volume fraction or the orientation of the piezoelectric phase. Four different composite configurations of single-crystal/polycrystal piezoelectric with polymer are analysed. Yet the polarisation orientation is found to play a crucial role in the piezoelectric response of ferroelectrics. The choice of an optimal composite is complicated, and it is impossible to analyse all possible permutations and combinations of the piezoelectric volume fractions, grain orientation distribution parameters (in the case of polycrystalline piezoelectrics plus polymer) or the crystallographic orientation angles (in the case of single-crystal piezoelectrics and polymer) themselves. Optimal design variables which would generate single-/polycrystalline configurations that enhance the macroscopic piezoelectricity of the composite are identified. It is found that juxtaposing a preferentially oriented piezoelectric material with a polymer into a composite would result in enhancement of piezoelectric figures of merit from constituent phases. It is shown that a small fraction of piezoelectric material ([Formula: see text]) is sufficient to design an optimal piezoelectric composite that can generate piezoelectric strains comparable to that of single-phase material.