Limit Elastic Analysis of Functionally Graded Rotating Disks Under Thermo-Mechanical Loading

Abstract

In this work, the thermo-mechanical limit elastic speed analysis of functionally graded rotating disk has been reported. Three different material models, i.e., power law (P-FGM), sigmoid law (S-FGM), and exponential law (E-FGM), along with varying disk profiles, namely uniform, tapered, and exponential disk profiles, are considered. The methodology adopted is variational principle wherein the solution has been obtained by Galerkin’s error minimization principle. Halpin–Tsai method was used to estimate the modulus, modified rule of mixture for yield strength, and the rule of mixture for density and coefficient of thermal expansion. This study aims to analyze the effects of material models, grading indices, aspect ratio, and disk geometry on disk performance when subjected to combined thermal and mechanical loadings. Finite element analysis has been performed to validate this study and good agreement between both the methods is seen. The study shows a substantial difference in the limit speed for different disk profiles changing from uniform thickness to exponentially varying thickness. The von Mises stress distribution and location of yielding at limit speed are shown for different indices, material models, and disk profiles. In P-FGM, limit speed decreases with the increase in grading indices whereas in E-FGM, limit speed decreases with the decrease in grading indices. For increase in aspect ratio, limit elastic speed decreases in all the cases.