Abstract EN:

There are lubricated contacts in several mechanical applications. In this thesis, we were interested in the particular case of lubricated contacts in the elastohydrodynamic lubrication (EHL) regime with spin motion and large contact size. This kind of contacts is industrially present in the taper roller bearing, between the end of the roller and the rib. Only few authors worked on the subject of EHL with a spin motion. However, these authors found that the spin leads to a decrease of the film thickness and the friction coefficient. To better understand how the spin modifies the contact conditions, a test rig and a numerical model were built. The test rig allowed us to simulate closely industrial contacts, both in term of spin quantity and contact size, whereas the numerical model enabled us to understand on which contact parameters the spin motion acts. First of all, the main tendencies measured with Tribogyr and the numerical model are the same as those found in the literature. Then other results were produced. Thanks to the large contact size and temperature measurements, we were able to quantify the thermal dissipation relatively to the contact condition. The result is that the thermal dissipation is linked with the level of spin introduced in the contact. Then, the numerical results showed that the film thickness decreases and looses its symmetry when a spin motion is introduced. The comparison of the results obtained with the test rig and the numerical model showed that the spin introduces an additional shear rate in both rolling and transversal direction that modifies the contact conditions. This additional shearing is not constant over the contact surface and generates a higher heat production and a viscosity reduction by shear thinning effect. Both of these effects lead to decrease the friction coefficient and the film thickness.