Porosity and size effects on electro-hygrothermal bending of FG sandwich piezoelectric cylindrical shells with porous core via a four-variable shell theory

Abstract

The sinusoidal four-variable shear deformation shell theory is employed, for the first time, to investigate the size dependent electro-hygrothermal bending of functionally graded (FG) sandwich piezoelectric cylindrical shells integrated with porous core. This model is assumed to be rested on two-parameter elastic foundations and subjected to elevated temperature, moisture concentration and external electric voltage as well as transverse mechanical loads. In order to take into account the size effect, the modified couple stress theory is employed containing only one length scale parameter. The core layer is assumed to be functionally graded porous material. Whereas, the face sheets are made of a functionally graded piezoelectric material which having gradient change along the thickness direction. Based on the sinusoidal four-variable shell theory, four governing equations are obtained involving external forces and foundation interaction, in addition to an equation associated to the electrical potential. An analytical solution for the obtained equations is presented to get the displacements and stresses of the FG sandwich piezoelectric cylindrical shells. Influences of the geometric parameters, material length scale parameter, temperature rise, moisture concentration, electric voltage, porosity factor, core thickness and foundation coefficients on the bending of the FG sandwich piezoelectric cylindrical shells resting on elastic foundations are discussed.