• An improved 3D anisotropic fractal model integrates tooth surface roughness and elastohydrodynamic lubrication for planetary gear meshing analysis.
• Asperity contact transforms the lubrication regime from EHL to mixed lubrication, reducing oil film stiffness.
• Ring-planet gears exhibit greater sensitivity to surface roughness than sun-planet gears, affecting meshing stiffness.
• Torque is the most influential parameter on meshing characteristics compared to roughness, speed, and viscosity.