Modal Analysis of a Thermally Loaded Functionally Graded Rotor System Using ANSYS

Abstract

To overcome the demerits of the traditional composite materials, such as debonding due to the high residual stress at inter-laminar layers and delamination of layers at higher temperature gradients, functionally graded materials (FGMs) have been developed. The present study deals with the modal analysis of a Jeffcott FG rotor system, consisting of an FG shaft mounted on linear bearings at the ends. The shaft is functionally graded which is made up of a mixture of stainless steel (SS) and zirconium dioxide (ZrO$_{2}$), where the volume fraction of metal (SS) decreases towards the outer radius and ceramic (ZrO$_{2}$) volume fraction increases. The material gradation is applied following the exponential gradation law, whereas the thermal gradients across the radius of the FG shaft are achieved through the exponential temperature distribution method (ETD). 3D finite element modelling and the modal analysis of the FG rotor system have been carried out using ANSYS software with suitable validations to determine the natural and whirl frequencies. A Python code was developed to generate the functionally graded temperature-dependent material properties of the shaft. The influence of material gradation and temperature gradients on the rotor-bearing system’s natural and whirl frequencies are studied.