FINITE ELEMENT ANALYSIS OF FUNCTIONALLY GRADED THICK-CYLINDERS SUBJECTED TO MECHANICAL AND THERMAL LOADS

Functionally graded materials (FGM) are used to design structures used in high temperature environment. Hybrid pressure vessels can be designed from FGMs to incorporate improved strength, weight reduction, thermal properties, impact resistance etc. Progressive research in this area will lead to the determination of optimum design parameters and provide insight in developing manufacturing techniques of full-scale hybrid pressure vessels and experimental validation. In future, an accurate damage model will help in planning component examinations in a selective manner in order to provide useful information about material condition and predict the remaining life of the structure. A functionally graded thick-walled cylindrical vessel with varying material properties in the radial direction is considered. The cylinder is assumed to be made of one phase spatially dispersed in a matrix of another. Volume fractions of the phases are assumed to vary along the radial direction according to power laws. The gradation is represented by dividing the radial domain into finite sub-domains. The effective material properties such as modulus of elasticity, Poisson's ratio, thermal conductivity and coefficient of thermal expansion are estimated using Mori-Tanaka [1], Hashin-Shtrikman [2], Hatta-Taya [3] and Rosen-Hashin [4] relations. The hollow cylinder is subjected to axisymmetric mechanical and thermal loadings. Finite Element Analysis is performed using a commercial package, ANSYS, to obtain temperature and stress component distribution along the thickness of the cylinder. Results are presented graphically to show the effect of internal pressure, temperature change, and gradient variation of material properties on stress components throughout the thickness.