Now more than ever, designers of efficient and long-lasting lubricated mechanisms need to consider constraints such as the continuous reduction of lubricant film thickness in lubricated systems, the emergence of new materials and the never-ending publication of new requirements around environmental issues such as reducing energy losses and conserving natural resources. This highly evolving context leads to an ever-increasing understanding of the mechanisms of both lubricant film formation and friction dissipation and ultimately helps to develop reliable prediction tools.
Lubricants and their thermo-physical properties play a central role in research that tackles new problems related to both the evolving operating conditions of rolling element bearings and the response of the lubricant applied to them. These aspects are being studied at LaMCoS – INSA Lyon in cooperation with SKF.
In the mid-1990s, the SKF European Research Center (SKF ERC, now Research & Technology Development, SKF-RTD) and the Laboratoire de Mécanique des Contacts (LMC, now Laboratoire de Mécanique des Contacts et des Structures, LaMCoS) at INSA Lyon began a collaboration on the lubrication of flange/roller-end contacts such as those found in large-size roller bearings. The key objective was to develop a new test bench, Tribogyr, dedicated to types of lubricated contacts that were barely considered in the scientific literature at that time. The unique specifications formulated by SKF included:
- simulate, on a 1:1 scale, a real contact such as those found in roller bearings with outside diameters of 600 to 1,000 mm (24 to 39 inches),
- reproduce the particular kinematics that can be found in these contacts, with an entrainment velocity and also with spin and skew components,
- respect the radii of curvature of the rolling bodies in the contact area, and
- measure the three forces and the torque acting on each of the two specimens.
When Tribogyr was validated and put into service, limitations quickly appeared when comparing the experimental results with simulations that allowed the scope of investigation to be extended and the lubricant to be artificially changed. Other approaches were gradually introduced in the projects on the study of large-size lubricated contacts with spinning using Tribogyr (see http://evolution.skf.com/the-beast-of-lyon-putting-large-bearing-contacts-to-the-test/). This research, which was mainly motivated by SKF, became part of a more general research framework that was previously established at LaMCoS and named “A quantitative multi-physics, multi-scale and multi-approach to lubrication and lubricants.”
This general framework is first presented here with some illustrations that refer to the flange/roller-end contacts. More specific aspects are detailed afterward, still in connection with the lubrication of heavily loaded contacts or elastohydrodynamic lubrication (EHL).