Failure and Friction Analysis for the Elastic and Thermal Behavior of an Aerodynamic Foil Bearing Operating in the Turbulent Regime

Aerodynamic foil bearings, used in high-speed applications, have to cope with extreme operating conditions involving high temperatures, high mechanical loads, turbulent regimes. Heating due to friction and aerodynamic losses can alter the materials and performance of the lubricating film, while significant variations in rotor speed and airflow fluctuations influence the stability and load-bearing capacity of the bearing, increasing the risk of wear, material fatigue and structural deformation. The research focuses on the analysis of the failure and wear of aerodynamic foil bearings subjected to a turbulent regime, taking into account their elastic and thermal behavior. The study explores the degradation mechanisms linked to mechanical and thermal stresses, which directly influence the tribological and structural performance while modifying the service life of these essential components in high-speed applications. By examining the impact of pressure fluctuations and thermal gradients, the analysis highlights the phenomena of accelerated wear, material fatigue and structural deformation of the sheets. Turbulence in the airflow alters the distribution of pressures and temperature, which can lead to instabilities, changes in the properties of the lubricant film and increased friction. This analysis is implemented on the one hand by solving the Navier-stokes continuity equations using the finite volume method (FVM), and on the other hand the notion of elasticity in CFD codes is based on formulations founded on the mechanics of continuous media, taking into account Hooke's law and the constitutive relations of materials (FEM). The numerical results demonstrate that increasing the rotational speed significantly impacts the aerodynamic foil bearing’s behavior, leading to higher mechanical stresses, heat flux, and pressure in the air film, which directly affects its stability and durability. The Von Mises stress, directional displacements, and elastic deformations increase substantially with speed, potentially causing plastic deformation, cracks, and vibratory instabilities that can compromise performance.