Dinh Gia Ninh

Nonlinear torsional buckling and post-buckling of eccentrically stiffened ceramic functionally graded material metal layer cylindrical shell surrounded by elastic foundation subjected to thermo-mechanical load

The nonlinear torsional buckling and post-buckling of ceramic functionally graded material (C-FGM-M) stiffened cylindrical shell surrounded by Pasternak elastic foundation in thermal environment are investigated in this paper. The C-FGM-M cylindrical shell is reinforced by ring and stringer stiffeners system in which the material properties of shell are assumed to be continuously graded in the thickness direction. Based on the classical shell theory, theoretical formulations are derived with the geometrical nonlinearity in von Karman sense and the smeared stiffeners technique. The three-term approximate solution of deflection is chosen more correctly and the explicit expression for finding critical load and post-buckling torsional load–deflection curves are given. The effects of geometrical parameters, temperature, stiffeners and elastic foundation are investigated.

FREE VIBRATION OF THICK COMPOSITE PLATES ON NON-HOMOGENEOUS ELASTIC FOUNDATIONS BY DYNAMIC STIFFNESS METHOD

This research presents a new model for vibration analysis of thick laminated plates on a non-homogeneous elastic foundation by the Dynamic Stiffness Method (DSM). The non-homogeneous foundation consists of multi-segment Winkler-type and Pasternak-type elastic foundation. The Dynamic Stiffness Matrices using the First Shear Deformation Theory (FSDT) are constructed for cross-ply thick composite plates. A computer program is written using the present formulation for calculating natural frequencies and harmonic response of composite plates subjected to various types of boundary conditions. Numerical results are validated by comparison with available results in the literature and with Finite Element Method (FEM). Different test cases make evidence the advantages of the present model: higher precision, less data storage, less computing time and studied frequency range extended.