Analytical Investigation of Nonlinear Free Vibration of Porous Eccentrically Stiffened Functionally Graded Sandwich Cylindrical Shell Panels

This paper introduces the nonlinear vibration response of an eccentrically stiffened porous functionally graded sandwich cylindrical shell panel with simply supported boundary conditions by using a new analytical model. The cylindrical shell has three layers: an FGM core layer and two layers made of isotropic homogeneous material. The FGM core properties are considered to be porosity dependent and varied in the thickness direction according to power-law distribution in terms of the volume fractions index of the constituents. Governing equations for the dynamic response of porous ES-FGM sandwich cylindrical shell panels are derived by combining classical shell theory and nonlinearity von Karman strains. Besides that, the airy stress function and Galerkin approaches are proposed to obtain the resulted equations: Fundamental natural frequency, dynamic response, and amplitude-frequency relation. Comparisons are made to estimate the reliability of the received results. Eventually, the effects of stiffeners, porous coefficient, face sheet thickness, material gradient, FGM core thickness, slenderness ratios, and excitation force on the natural frequency and nonlinear dynamic response of porous FGM sandwich cylindrical shell panels are also clarified in this paper.