Investigation of Lubrication Effects on Gear and Bearing Dynamic Operational Performance

Abstract

This study examines how lubrication properties particularly viscosity and film thickness affect the dynamic performance of gears and bearings through a MATLAB-based simulation. The gear and bearing assemblies were represented as single-degree-of-freedom (SDOF) systems with lubrication-dependent damping. In the simulations, viscosity (η) was varied between 0.01 and 0.1 Pa∙s, while film thickness (hf) ranged from 1×10⁻⁶ to 1×10⁻⁵ m. Dynamic responses, including peak vibration, RMS vibration, and load distribution, were evaluated using 3D surface and contour plots. The results show that increasing viscosity reduces peak gear vibration from 0.98 m to 0.55 m and peak bearing vibration from 0.51 m to 0.30 m equivalent to a reduction of about 44% and 41%, respectively. Load analysis further reveals that gear and bearing loads decrease by nearly an order of magnitude with greater film thickness, underscoring the importance of lubrication in reducing mechanical stress. Contour plots identified vibration hotspots under conditions of low viscosity and thin films, highlighting regions most vulnerable to wear and failure. The analysis results provide practical guidance for selecting lubricants and optimizing mechanical system performance. They also address a key gap in the literature by quantifying how the combined effects of viscosity and film thickness influence the dynamic behaviour of gear–bearing systems, an area that has received limited attention in prior research.