ELECTRO-THERMO-MECHANICAL RESPONSE OF THICK-WALLED PIEZOELECTRIC CYLINDER REINFORCED BY BORON-NITRIDE NANOTUBES

Abstract

Electro-thermo-elastic stress analysis of piezoelectric polymeric thick-walled cylinder reinforced by boron-nitride nanotubes subjected to electro-thermo-mechanical fields is presented. The electrothermo- elastic properties of piezoelectric fiber reinforced composite was studied by a modified XY micromechanical model capable of exhibiting full coupling relation between electric, thermal and elastic fields. Assuming piezoelectric fiber reinforced composite material and its composite constituents to be linear, homogenous, orthotropic, and perfectly bonded with uniform applied field, the basic relation for the axisymmetric deformation of a thick-wall cylinder subjected to uniform internal and external pressures, an axial electrical load, a temperature change between inner and outer radius are derived. Although the cylinder has end caps and is free to change length, displacement, strains, and stresses at location far removed from the end caps have been investigated. The stress results suggest that increasing boron-nitride nanotubes content in longitudinal direction reduces the effective stress. Displacement along radial direction indicates an optimum content of 5% boron-nitride nanotube for this. Furthermore, at normal working conditions, the influence of thermal and mechanical fields are much higher than the electric one on the effective stress; hence, this smart structure is best suited for applications as sensors than actuators.