This thesis is devoted to the study of spinning contacts located in bearing between the roller-end and the ring flange. The main direction of the lubricant flow may change when the contact is subjected to skew. This complex kinematics influences the contact behaviour. A dual experimental-numerical approach is proposed to study this problem. The Tribogyr test-rig allows the experimentation of the contact at the 1:1 scale. A film thickness measurement method, based on white light interferometry, was developed on Tribogyr. This method allows the measurement of film thickness between 0 and 800 nm with an accuracy of a few nanometres. The measurement of forces in the main flow direction shows similarities with classical rolling-sliding contacts. However, the friction coefficient is globally lower as soon as spin is involved. Transverse forces are of the same order of magnitude as the longitudinal forces. This is due to transverse shearing caused by the spin. A numerical model has been developed for the simulation of these spinning contacts. The finite element model, which is based on a fully-coupled solving strategy, takes into account the temperature calculation and the lubricant non-Newtonian rheology. Its validation with Tribogyr experimental results in terms of film thickness and friction has been conducted. Spin and skew effects induce high shear-thinning and thermal-thinning of the lubricant that lead to a decrease of the film thickness. Under high spinning condition, the lubricant exiting the contact may be re-injected to the contact inlet. Consequently, the heat transfers between the lubricant and the solids in contact are modified. In contact subjected to high skew, a local increase (dimple) of the film thickness may occur. Important skew may also lead to starvation conditions. Many experimental campaigns, coupled with an intensive use of the numerical model, allowed to understand the physical phenomena involved as well as to predict the efficiency, in terms of power losses, of the spinning contacts.
| Identifer | oai:union.ndltd.org:CCSD/oai:tel.archives-ouvertes.fr:tel-00749882 |
| Date | 03 July 2012 |
| Creators | Doki-Thonon, Thomas |
| Publisher | INSA de Lyon |
| Source Sets | CCSD theses-EN-ligne, France |
| Language | English |
| Detected Language | English |
| Type | PhD thesis |
Page generated in 0.0017 seconds