Piezoelectric performance of piezoceramic-polymer composites with 2-2 connectivity-a combined theoretical and experimental study

The piezoelectric performance of piezoceramic-polymer composites with 2-2 connectivity at low frequency has been analyzed theoretically. Due to the elastic coupling between the ceramic and polymer phases, the strain components in directions perpendicular and parallel to the ceramic-polymer interface are not uniform in either phase. As a result, most of the stress transfer between the two phases occurs at the region near the surface of the composite. In order to improve the piezoelectric performance of a composite, the polymer matrix should have a small Young´s modulus and a large shear modulus, and a large aspect ratio. It may be also desirable to have the polymer matrix made of two different polymers with the stiffer one near the surface and the softer one in the interior of the composite. To compare with the theoretical calculations, surface profiles of a series of 2-2 composites with different aspect ratios were measured, and the experimental results show excellent agreement with the theoretical calculations. The nonuniform strain and stress in the direction parallel to the ceramic-polymer interface of a composite were also confirmed by experiments.<>