ELECTROMECHANICAL RESPONSE OF PIEZOELECTRIC FOAMS: EFFECTS OF FOAM SHAPE AND POROSITY ASPECT RATIO

摘要

A finite element based three-dimensional numerical model has been developed to completelycharacterize the elastic, piezoelectric and dielectric properties of 3-3 type piezoelectric foamstructures. Upon identifying 15 characteristic foam structures based on foam shape and porosityaspect ratio, the influence of foam shape, porosity aspect ratio, and volume fraction on theeffective properties of foam structures is examined. In general, as the material volume fractionincreases the elastic, piezoelectric and dielectric properties (with exception of κ_(11) for all thestructures and κ33 for some structures) of piezoelectric foam structures increase nonlinearly.Furthermore, the utility of piezoelectric foams for specific applications are assessed byquantifying select figures of merits. Desirable combination of properties (for hydrophoneapplications) such as low acoustic impedance, high hydrostatic voltage coefficient and highhydrostatic figure of merit is obtained in longitudinally short structures with flat porosity(b=0.25a) and equiaxed foam structures with porosity aspect ratio of 1.