[SY-O5] Symposium O-5

[SY-O5] Ultimate response of confined fluids under extreme conditions: a Molecular Dynamics analysis

^○Alejandro Porras-Vazquez, Laetitia Martinie, Philippe Vergne, Nicolas Fillot (INSA Lyon, France)

In order to control energy losses in mechanical systems, the study of friction in lubricated contacts has to be approached. Depending on the operating conditions and its chemical nature, the confined fluid can exhibit a limiting shear stress at high pressure [1, 2]. The physical origins of this phenomenon and its implications to friction are currently not completely understood [3]. In this study, an extensive Molecular Dynamics analysis of the shearing behavior of different types of molecules is performed. The behavior of the confined sheared system is explored and compared to the fluid bulk state. One of the main conclusion is that flow profile results from two competing forces in the molecular system, which is linked to the weakest interfaces being sheared. Additionally, the saturated shear stress response is found to be related to the concept of atomic mobility. With increasing pressure, the relaxation time of the material is increased. Thus, atomic mobility can be saturated for a range of high pressures, diffusion would not be allowed, and a solid-like behavior is displayed. Finally, a link between flow and friction behavior is discussed.


[1] Martinie, L. and Vergne, P., “Lubrication at extreme conditions: a discussion about the limiting shear stress concept”, Tribol. Lett., 63, 2016.

[2] Ewen, J. P., Gattinoni, C., Zhang, J., Heyes, D. M., Spikes, H. A. and Dini D., “On the effect of confined fluid molecular structure on nonequilibrium phase behaviour and friction”, Phys. Chem. Chem. Phys., 2017.

[3] Ndiaye, S. N., Martinie, L., Philippon, D., Devaux, N. and Vergne, P., “A Quantitative Friction-Based Approach of the Limiting Shear Stress Pressure and Temperature Dependence”, Tribol. Lett., 65, 2017.