Molecular dynamics study of contact mechanics: contact area and interfacial separation from small to full contact

TL;DR

This molecular dynamics study investigates how contact area and interfacial separation evolve from small to full contact between a rough rigid surface and an elastic block, revealing linear and logarithmic behaviors under different load regimes.

Contribution

It provides detailed molecular dynamics insights into contact mechanics across the full spectrum from partial to complete contact, highlighting behaviors relevant for soft solids and smooth surfaces.

Findings

Contact area increases linearly with load at small loads.

Interfacial separation depends logarithmically on load at small loads.

Complete contact is achievable at moderate loads without plastic deformation.

Abstract

We report a molecular dynamics study of the contact between a rigid solid with a randomly rough surface and an elastic block with a flat surface. We study 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 to the nominal contact area (i.e., complete contact), and the interfacial separation approaches to zero. The present results 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.