Traction behaviour of elastohydrodynamic lubrication films with anomalous shapes

This study describes traction behaviours of lubricant films having anomalous shapes under elastohydrodynamic lubrication conditions. The traction generated at a point contact area between a glass or sapphire disc and a steel ball was measured by changing the slide-to-roll ratio. Three alcohols, 1-dodecanol, ethylene glycol and glycerol, and two alkanes of n-tetradecane and n-hexadecane were used as lubricants. Lubricants developing anomalous film shapes exhibited a solid-like behaviour with a sharp traction peak at low slide-to-roll ratios. On the contrary, other lubricants having conventional film shapes indicated a gradual increase in traction coefficient with increasing slide-to-roll ratios. The similarity of the traction behaviour to that of traction fluids supports the solidification of the film, which developed anomalous film shapes.