On a recent very simple generalization of DMT theory of adhesion

TL;DR

This paper discusses a simplified version of the DMT adhesion theory, examining its applicability at small scales and analyzing discrepancies with classical models, especially in the context of rough contacts.

Contribution

It critically evaluates a recent simplified DMT model, highlighting its successes and conflicts with established theories for spherical contacts.

Findings

Simplified DMT model works well in numerical experiments for rough contacts.

Significant conflicts exist between the simplified model and classical sphere theories.

The reasons for the model's success in experiments remain unclear.

Abstract

As the interest in adhesion is shifting towards smaller and smaller scales, the well known Tabor adhesion parameter decreases and the DMT theory is frequently considered to be the appropriate limit. A very attractive much simplified version of DMT has been proposed in a recent investigation of rough contacts by Pastewka & Robbins (PNAS, 111(9), 3298-3303, 2014) which seems to work in very general conditions in numerical experiments. However, when comparing this calculation to the known theories for the sphere, surprisingly large conflicts occur, and the reason for the success of the numerical experiments is obscure.