Active control for ratios of strains in functionally graded piezoelectric composites

Abstract

Poisson’s ratio measured by the ratio of transverse strain to longitudinal strain is an important intrinsic property of materials. Imitating the definition of Poisson’s ratio, we define that the ratio of strains is denoted by the ratio of any two normal strains. Nowadays, some design methods have been proposed to tailor the ratios of strains by changing Poisson’s ratio in materials. However, the ranges of the ratios of strains by available methods are too narrow, the technology can provide materials with tailorable ratios of strains over an extremely wide range is rarely studied. To this end, we propose that the ratios of strains in piezoelectric composites can be active-controlled by simultaneously tailoring force and electric fields. The analytical solutions for different ratios of strains in piezoelectric composites subjected to force and electric fields are presented. It is demonstrated that the range of tunable ratios of strains can be from giant negative to giant positive. Moreover, the ratios of strains in any location of FG piezoelectric composites can be greatly affected by force field, electric field, polarization direction, volume fraction of piezoelectric phase. The present study may open up a new routine to design materials possessing extraordinary and programmable mechanical behaviors.