Dynamic Response of Hydrodynamic Journal Bearings With Rectangular Macro‐Grooves and Nano‐Lubricant Additives

ABSTRACT The present study investigates the dynamic characteristics of journal bearings with rectangular macro‐grooves, focusing on parameters such as stiffness, damping coefficients and stability threshold speed. Using the finite element method to solve the governing Reynolds equation for lubricant flow, the analysis explores the influence of varying macro‐groove texture numbers, groove depth and area density across different bearing regions such as the full region, first half, second half and pressure‐increasing region to identify the optimal performance parameters in each region. Findings reveal that both stiffness and dynamic coefficients of the journal bearing improve at higher and lower eccentricity ratios. Among the various investigated macro‐grooved regions, at an eccentricity ratio of 0.2, the maximum enhancement of stability threshold speed of 84.23% is found for full grooved macro rectangular‐textured surface with two macro‐grooves at non‐dimensional groove depth of 0.9 with an area density of 54.01%. Additionally, incorporating 0.5% weight fractions of copper oxide and cerium oxide nanoparticles into the base lubricating oil at 90°C significantly enhances stiffness, damping coefficients and stability threshold speed.