Out-of-contact elastohydrodynamic deformation due to lubrication forces

TL;DR

This paper investigates how elastic deformation in thin films during fluid drainage affects contact mechanics, revealing that deformation prevents full contact and influences hydrodynamic forces, with implications for lubrication and material design.

Contribution

It introduces a detailed characterization of elastic deformation during fluid drainage, highlighting the effects of film thickness and viscoelasticity on contact and force dynamics.

Findings

Thinner elastic films support more stress on the substrate, reducing dimple formation.

Deformation causes stronger hydrodynamic forces compared to rigid surfaces.

Viscoelastic effects introduce lag in surface profile evolution.

Abstract

We characterize the spatiotemporal deformation of an elastic film during the radial drainage of fluid from a narrowing gap. Elastic deformation of the film takes the form of a dimple and prevents full contact to be reached. With thinner elastic film the stress becomes increasingly supported by the underlying rigid substrate and the dimple formation is suppressed, which allows the surfaces to reach full contact. We highlight the lag due to viscoelasticity on the surface profiles, and that for a given fluid film thickness deformation leads to stronger hydrodynamic forces than for rigid surfaces.