Dynamic analysis of functionally graded sandwich plate and shell panels including multifield interaction

Abstract

The work in this thesis presents the dynamic analysis viz., free vibration, linear newlinetransient and nonlinear transient analysis of the FGM sandwich plates and shell panels newline(FGSSP). Two different sandwich configurations are considered, one having a pure newlinemetallic core with bottom and top facesheets made of FGM termed Type I and the other newlineone having an FGM core with the bottom and top facesheets made of pure metal and pure newlineceramic, respectively termed as Type II. The metallic and ceramic constituents of the newlineFGM layers for the two configurations varies along the thickness direction according to newlinethe power-law (P-FGM) and sigmoid (S-FGM) models respectively. For practical newlineanalysis, the effect of skew edges and porosity in the FGM layers of FGSSP is taken into newlineconsideration. The FGM layers for the two configurations are porous and two types of newlineporosity, viz., evenly spaced and unevenly spaced are considered for the analysis. A newlinesimple and accurate finite element formulation based on three different displacement newlinefields viz., first-order layerwise theory (FLWT), a newly developed higher-order newlinelayerwise theory (HLWT) and first-order shear deformation theory (FSDT) having C0 newlinecontinuity of transverse displacement is used for the present investigation. FEM model is newlinebased on eight node isoparametric elements for the dynamic analysis of Type I and Type newlineII, porous P-FGSSP and S-FGSSP. The governing differential equation of dynamic newlineproblems is obtained by the virtue of Hamilton s principle. Subsequently, the NewmarkBeta time integration scheme is used to obtain the transient response of FGSSP. Further newlinefor nonlinear problems of blast analysis of FGSSP, the strain-displacement relation is newlineobtained using Sander s approximation incorporating von Karman type nonlinear strains. newlineThe material properties are considered to be temperature-dependent and independent for newlinenonlinear and linear problems, respectively. The governing nonlinear equations are newlinederived from the virtual work principle based on the total Lagrangian approach.