4-years PhD funding titled Determination of EHD film parameters to reduce friction

All dynamic mechanical systems, in industry, home appliances or transportation, utilize contacting components such as gears and bearings to transfer energy and reduce losses by enabling low-friction motion among different components. These nonconformal contacts have small contact areas, leading to high contact pressures and must be lubricated to prevent friction and wear. As much as 80 % of all lubricated contacts operate in the ElastoHydroDynamic (EHD) lubrication regime where the entrained lubricant separates two elastically deformed contacting surfaces with a thin film, yet thick enough to prevent any direct asperity contacts and thus wear. Experimental and theoretical study of EHD contacts is thus an important research area, central to achieving the transition to green technologies.

The surfaces of the contacting bodies specifically designed to additionally reduce friction in the EHD regime often differ from the standard steel interfaces in such a way (different colour, texture, roughness) that special methodology, currently only available at TINT laboratory, needs to be employed to access their most important lubrication parameters: film thickness and film pressure distributions. As part of this doctoral dissertation, the young researcher will take advantage of this extended white light interferometric detection method to overcome the current limitations of the EHD test rig. The student will first get acquainted with this method by reviewing the literature on EHD thin film generation and detection and then by performing thin film measurement using the conventional steel-on-glass contacts. Then he/she will carefully model, calibrate, and validate the EHD film measuring device using coloured and rough contacts against conventional measuring and numerical methods to prove its robustness, exactness, and reliability. These experimental advances will then enable the student to study friction reduction using low-surface-energy, diamond-like-carbon (DLC) coated surfaces and other oleophobic, slip-inducing surfaces engineered for low friction.

The aim of the doctoral thesis will thus be to exploit the robust optical detection method that enables 3D measurements of EHD film thickness of steel and non-steel contacts with surfaces of different colours and roughnesses. Its applicability will be demonstrated on coloured engineering materials (ceramics, nitride coatings), DLC coated surfaces and other surfaces designed for low friction.

RESEARCH FIELD

Tribology, Photonics, Electrodynamics, Hydrodynamics, Numerical modelling

The work is dynamic, underpinned by experimental research by other colleagues and the use of technical problems with various modern surface-enhancing materials.