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Article Dans Une Revue Langmuir Année : 2018

Friction of poroelastic contacts with thin hydrogel films

Résumé

We report on the frictional behaviour of thin poly(dimethylacrylamide) (PDMA) hydrogels films grafted on glass substrates in sliding contact with a glass spherical probe. Friction experiments are carried out at various velocities and applied normal loads with the contact fully immersed in water. In addition to friction force measurements, a novel optical setup is designed to image the shape of the contact under steady-state sliding. The velocity-dependence of both friction force Ft and contact shape is found to be controlled by a Péclet number Pe defined as the ratio of the time τ needed to drain the water out of the contact region to a contact time a/v, where v is the sliding velocity and a is the contact radius. When Pe¡1, the equilibrium circular contact achieved under static normal indentation remains unchanged during sliding. Conversely, for Pe¿1, a decrease in the contact area is observed together with the development of a contact asymmetry when the sliding velocity is increased. A maximum in Ft is also observed at Pe ≈ 1. These experimental observations are discussed in the light of a poroelastic contact model based on a thin film approximation. This model indicates that the observed changes in contact geometry are due to the development of a pore pressure imbalance when Pe¿1. An order of magnitude estimate of the friction force and its dependence on normal load and velocity is also provided under the assumption that most of the fric-tional energy is dissipated by poroelastic flow at the leading and trailing edges of the sliding contact.
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Dates et versions

hal-01893850 , version 1 (11-10-2018)

Identifiants

  • HAL Id : hal-01893850 , version 1

Citer

Jessica Delavoipière, Emilie Verneuil, Yvette Tran, Antoine Chateauminois, Bertrand Heurtefeu, et al.. Friction of poroelastic contacts with thin hydrogel films. Langmuir, 2018. ⟨hal-01893850⟩
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