Vibrational behavior of doubly curved smart sandwich shells with FG-CNTRC face sheets and FG porous core

As a first endeavor, the free flexural vibration behavior of doubly curved complete and incomplete sandwich shells with functionally graded (FG) porous core, FG carbon nanotube reinforced composite (FG-CNTRC) face sheets and integrated piezoelectric layers is investigated. The variable radii shells with the three most common types of geometries, i.e., elliptical, cycloid and parabolic, are considered. The system equations are derived based on the general higher-order shear deformation theory and Maxwell's equation. The generalized differential quadrature (GDQ) method is employed to discretize the governing partial differential equations subjected to different boundary conditions. The accuracy and reliability of the approach are verified by comparing the results with the existing solutions in open literature. The effects of porosity parameter and porosity distribution through the thickness direction, carbon nanotube (CNT) volume fraction, different boundary conditions and various shell geometrical parameters on the flexural vibrational behavior of the smart sandwich shell structures are investigated and useful results are presented.