Asperities Friction Review
Asperities. Regardless of how smooth a
surface may appear, it has many small irregularities called
asperities. In cases where a surface is extremely rough, the
contacting points are significant, but when the surface is
fairly smooth, the contacting points have a very modest
effect. The real or true surface area refers to the area of
the points in direct contact. This area is considerably less
than the apparent geometric area.
Friction is also proportional to the size of the asperities, so larger asperities result in increased friction and vice versa. This has resulted in the development of nearly frictionless materials with minuscule asperities.