An Investigation into the Orientation of lubricant Molecules in EHD contacts

There is growing evidence from infrared and from computer simulation work that the very high shear stresses associated with elastohydrodynamic (EHD) contacts result in the partial alignment of lubricant molecules. Such an effect has important implications with respect to the lubricant’s EHD film forming and traction behaviour.

In this Paper, the film formation and alignment of thermotropic liquid crystals are studied in an EHD point contact. Two complementary experimental techniques are employed, in-contact, infrared reflection absorption spectroscopy and polarised, thin film optical interferometry. The work shows the extent and direction of orientation of liquid crystal molecules in EHD contacts and indicates how similar effects can be studied in more conventional lubricants.