Transient nonlinear modeling of lemon bore journal bearings with micropolar fluid and eccentricity effects
摘要
This research examines the stability characteristics of a lemon bore hydrodynamic journal bearing operating with micropolar fluid lubrication. It investigates the impact of micropolar parameters on the dynamic stability of the bearing system through nonlinear transient analysis. The Reynolds equation, modified to include micropolar fluid theory, is solved numerically using the finite difference method with the Successive Over-Relaxation (SOR) technique and Swift–Stieber boundary conditions. Static and dynamic performance characteristics are evaluated computationally and validated against published results. Stability parameters, including critical mass, threshold speed, and whirl frequency ratio, are calculated for both Newtonian and micropolar lubricants to assess the influence of microstructural fluid properties. Journal center trajectories are plotted by solving the nonlinear equations of motion via the fourth-order Runge–Kutta method, enabling an accurate evaluation of the system’s stability margin. The results indicate that incorporating micropolar effects markedly enhances the stability margin of the journal bearing, particularly under high load conditions. At higher eccentricity, an increased coupling number (