Nonlinear transient analysis of porous P-FGM and S-FGM sandwich plates and shell panels under blast loading and thermal environment

摘要

The present work is an attempt to develop a simple and accurate finite element formulation based on C-0 continuity of transverse displacement for obtaining and comparing nonlinear transient response of porous functionally graded material (FGM) sandwich plates and shell panels. The volume fraction for the layers made of FGM is computed according to the power-law (P-FGM) or sigmoid (S-FGM) model. The FGM sandwich panel is subjected to blast loading and thermal environment considering the heat conduction in thickness direction and the material properties are assumed to be temperature-dependent. An eight-noded isoparametric element along with first-order shear deformation theory is used to develop a finite element model. The strain- displacement relation is obtained using Sander's approximation incorporating von Karman type nonlinear strains. Two configurations, first having the top and the bottom layers made of pure ceramic and pure metal and the core of same composed of FGM, second having the top and the bottom layers made of FGM and the core composed of pure metal are considered for the present investigation. The FGM layers for the two configurations are porous and two types of porosity, viz., evenly spaced and unevenly spaced are considered for the analysis. The results obtained from the present finite element formulation are first validated with several benchmark examples available in the literature. Parametric studies are carried out to investigate the effect of volume fraction index, porosity model, temperature gradient, core to facesheet thickness ratio and blast load on nonlinear transient analysis of porous P-FGM and S-FGM sandwich plate and shell panels. It is observed that by selecting optimum parameters, the amplitude of the nonlinear transient response due to different blast loading is controlled.