Elastohydrodynamic contacts are concentrated contacts which commonly occur in mechanical power-tranmsission machinery, for example between the teeth of gears in mesh, or between the roller and raceway in rolling element bearings.  In these situations a hydrodynamic film of highly pressurised lubricant a few microns thick separates the contacting surfaces.  The Cardiff Tribology group has a long-established expertise in numerical simulation of the elastohydrodynamic problem, and the results of such simulations are highly dependent on the way in which the lubricant rheological and non-Newtonian behaviour is modelled.   
This presentation summarises work carried out over a number of years to develop a method of determining lubricant models based on careful experimental measurements of temperature distributions using thermocouples embedded in contacting bodies in an EHL test rig.  Frictional heat is dissipated at the contact, and using a numerical heat conduction model with an error minimisation technique, the contact frictional heat flux (and the division of this frictional heating between both surfaces) was determined by minimising the error between calculated and measured temperature distributions.  Following this, a range of lubricant models were used to determine the appropriate rheology to match the measured frictional heating behaviour.  The effect of errors or uncertainties in the measured data is discussed, together with ongoing work to improve the technique.