Multiscale Modeling of Stiffness, Friction and Adhesion in Mechanical Contacts
Abstract
The mechanical behavior of contacts plays a critical role in the function of devices from aircraft engines to microelectromechanical systems. As the demands for performance from these devices increase or their size shrinks, traditional continuum models of contact behavior become inadequate. This project developed methods for including atomistic effects in systems with up to micrometer dimensions. The methods were used to examine contact, friction, adhesion and stiffness of single and multiasperity contacts. The interfacial stiffness was found to scale linearly with contact area and load and to obey a simple scaling law with a universal prefactor. A simple predictive relation for the contact area between adhesive surfaces was developed and tested. It explains why adhesion is not observed between most macroscopic surfaces, but can be seen with elastomeric materials. Thermal fluctuations were shown to produce instantaneous pressures that are comparable to the ideal hardness. Simulations of large single asperity contacts showed large decreases in friction coefficient with increasing size, but did not show the partial slip predicted by continuum models. The widely used bearing area model was tested and found to give incorrect predictions for contact-contact correlations.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 29, 2012
- Accession Number
- ADA565301
Entities
People
- Mark O. Robbins
Organizations
- Johns Hopkins University