Fundamental frequency analysis of a thermally loaded corroded exponentially graded rotor bearing system

ABSTRACT Corrosion is an unintentional degradation of a material, which transpires due to harsh environmental conditions. It is a surface phenomenon that results in loss of material, which affects the dynamic characteristics and structural integrity of any structure. Fundamental frequency analysis of a corroded functionally graded (FG) rotor-bearing system using finite element method (FEM) for flexural vibrations is presented in work. A functionally graded (FG) shaft, Stainless Steel as the inner-metal core and Zirconia as the outer-ceramic layer is considered. Exponential gradation law is followed to assign the material properties along the radial direction of the shaft. The exponential temperature distribution (ETD) method based on Fourier law of heat conduction has been used for the temperature distribution across the cross-section of the FG shaft. Finite element formulations of a corroded FG shaft element have been developed using Timoshenko beam theory. An FE code is developed to compute the natural and whirl frequencies of an FG rotor-bearing system for various parameters such as corrosion length, position, depth and thermal gradients to investigate the influence of corrosion on fundamental frequencies. It has been investigated that there is a significant influence of corrosion parameters on the natural and whirl frequencies of an FG rotor-bearing system.