Adhesive Contact of a Compliant Sphere to an Elastic Coated Substrate: The Thin Film Limit

Abstract

Experimental results for adhesive contacts on substrates coated with elastomeric thin films have recently been obtained by Tardivat and Léger [1] by the so-called Johnson-Kendall-Roberts (JKR) test, which provides both adhesion energy and elastic modulus. These data show that on substrates coated with thin films the adhesion and effective elastic modulus of the sphere depend upon the film thickness. In keeping with the experimental conditions, we try to interpret these data using a simple model [4] in the thin film limit, i.e., when the film thickness is small compared with the contact radius. Although the film does impact the local crack tip stress field, we show that no effect on the macroscopic contact variables is expected for the adhesion to coated substrates in such confined geometries. The deviations from the experimental results are ascribed to the idealized contact boundary conditions assumed in the model.

Keywords:

• Adhesion
• Coating
• Contact
• Elasticity
• JKR test
• Thin film

Notes

One of a Collection of papers honoring Liliane Léger, the recipient in February 2007 of The Adhesion Society Award For Excellence in Adhesion Science, Sponsored by 3M.