Continuum contact models for coupled adhesion and friction

TL;DR

This paper introduces two innovative continuum contact models that accurately describe coupled adhesion and friction, including sliding under tensile forces, especially useful for soft, compliant systems like adhesive pads.

Contribution

The paper presents novel continuum contact models capable of modeling sliding friction under tensile normal forces, addressing limitations of existing models for soft and compliant materials.

Findings

Models agree with experimental results for sliding onset.

Models enable simulation of sliding under tensile normal forces.

Address limitations of previous models for soft systems.

Abstract

We develop two new continuum contact models for coupled adhesion and friction, and discuss them in the context of existing models proposed in the literature. Our new models are able to describe sliding friction even under tensile normal forces, which seems reasonable for certain adhesion mechanisms. In contrast, existing continuum models for combined adhesion and friction typically include sliding friction only if local contact stresses are compressive. Although such models work well for structures with sufficiently strong local compression, they fail to capture sliding friction for soft and compliant systems (like adhesive pads), for which the resistance to bending is low. This can be overcome with our new models. For further motivation, we additionally present experimental results for the onset of sliding of a smooth glass plate on a smooth elastomer cap under low normal loads. As shown, the findings from these experiments agree well with the results from our models. In this paper we focus on the motivation and derivation of our continuum contact models, and provide a corresponding literature survey. Their implementation in a nonlinear finite element framework as well as the algorithmic treatment of adhesion and friction will be discussed in future work.