JOT 2003 Abstract
A Scale-Dependent Model for Multi-Asperity Contact and Friction
As loading forces decrease in applications such as MEMS and NEMS devices, the size of the asperity contacts which comprise the real contact area
tend to decrease into the nano scale regime. This reduction in size of the contacts is only partially offset by the nominally increased smoothness of these
contacting surfaces. Because the friction force depends on the real area of contact, it is important to understand how the material and topographical
properties of surfaces contribute to friction forces at this nano scale.
George G. Adams, Sinan Müftü and Nazif Mohd Azhar
In this investigation, the single asperity nano contact model of Hurtado and Kim is incorporated into a multi-asperity model for contact and
friction which includes the effect of asperity adhesion forces using the Maugis-Dugdale model. The model spans the range from nano-scale
to micro-scale to macro-scale contacts. Three key dimensionless parameters have been identified which represent combinations of surface
roughness measures, Burgers vector length, surface energy, and elastic properties. Results are given for the friction coefficient vs. normal force,
the normal and friction forces vs. separation, and the pull-off force for various values of these key parameters.