Contact mechanics: contact area and interfacial separation from small contact to full contact

TL;DR

This study uses molecular dynamics to analyze how contact area and interfacial separation evolve from small to full contact between rough surfaces and elastic solids, validating results with theory and experiments.

Contribution

It provides detailed molecular dynamics insights into contact mechanics, especially the transition from partial to full contact, aligning with analytical and experimental findings.

Findings

Contact area scales linearly with load at low contact

Interfacial separation depends logarithmically on load at low contact

Complete contact is achievable at moderate loads without plastic deformation

Abstract

We present a molecular dynamics study of the contact between a rigid solid with a randomly rough surface and an elastic block with a flat surface. The numerical calculations mainly focus on the contact area and the interfacial separation from small contact (low load) to full contact (high load). For small load the contact area varies linearly with the load and the interfacial separation depends logarithmically on the load. For high load the contact area approaches the nominal contact area (i.e., complete contact), and the interfacial separation approaches zero. The numerical results have been compared with analytical theory and experimental results. They are in good agreement with each other. The present findings may be very important for soft solids, e.g., rubber, or for very smooth surfaces, where complete contact can be reached at moderate high loads without plastic deformation of the solids.