Thin films in hydrodynamic lubrication regime: The Osiris friction setup

Area of Science:

• Tribology
• Fluid Mechanics
• Surface Science

Background:

• Hydrodynamic lubrication is crucial for reducing friction and wear in machinery.
• Understanding thin film lubrication with low-viscosity fluids is challenging due to complex phenomena.
• Surface effects significantly influence lubrication performance, but their precise role is not fully understood.

Purpose of the Study:

• To develop and validate a novel hydrodynamic lubrication tribometer for investigating thin film lubrication.
• To analyze the mechanisms of hydrodynamic friction in low-viscosity fluids.
• To elucidate the role of surface effects, including topography and adsorbed layers, on lubrication.

Main Methods:

• Development of a specialized hydrodynamic journal bearing tribometer with a 5 µm radial clearance.
• In situ simultaneous measurements of film thickness, cavitation zones, friction torques, temperature, and shaft position.
• Testing under various conditions, including smooth and textured surfaces, at speeds up to 12,000 rpm.

Main Results:

• The tribometer successfully measured thin film characteristics and friction.
• Thermal effects, acceleration, and inertia were quantified and discussed.
• Surface topography (texturing) and adsorbed fluid layers demonstrably influenced lubrication performance.

Conclusions:

• The developed tribometer is a capable tool for studying thin film hydrodynamic lubrication.
• Surface topography and fluid formulation-induced adsorbed layers play a significant role in lubrication mechanisms.
• Further research can leverage this setup to optimize lubricant formulations and surface designs for enhanced tribological performance.