folyóiratnyomást

Folyóiratnyomás, in tribology, denotes the pressure distribution within the lubricant film that separates a rotating journal from the bearing surface. The term is primarily used in the analysis of journal bearings and related configurations. The pressure field arises from viscous forces in the lubricant together with the geometry of the clearance, the speed of the journal, and any external forces acting on the bearing. In hydrostatic or hybrid bearings, external pressure sources can also contribute to the film pressure.

The classical mathematical treatment uses lubrication theory. In thin-film regions, the Reynolds equation describes how the film pressure p varies with position, given the film thickness h, lubricant viscosity μ, and the kinematics of the moving parts. Solving this equation with appropriate boundary conditions yields the pressure distribution over the bearing surface. The resulting folyoiratnyomás determines the load-carrying capacity, stiffness, and damping of the bearing, as well as the rate of heat generation due to viscous dissipation. Large or highly uneven pressures can increase wear and thermal load, while too low pressures risk metal-to-metal contact and seizure.

Measurement of folyoiratnyomás is challenging; in practice, pressures are often inferred from bearing load, temperature, and film thickness data or estimated numerically from geometry and operating conditions. Applications span the design of journal bearings in engines, turbines, electric machines, and precision spindles. The concept also appears in elastohydrodynamic lubrication, where surface deformation modifies the pressure field.