Overview
Contact mechanics is a classical subject which tells us about the nature of the pressure distribution and size of contacts when objects are pressed together. The ‘analytical’ side of the subject reached its apparent heyday when so called ‘halfspace’ theory became fully developed, by something like the 1980s.
It was always very difficult to use analytical models to explain the behaviour of contacts which were not amenable to this sort of approach, such as sharp contacts involving blocks, or those contacts which recede when load is applied, such as bolted joints.
But, by looking specifically at the edges of the contact we can learn a tremendous amount about what to expect in terms of the friction to keep things fully stuck together; on the other hand we can show that, under some conditions, no matter how big the frictional force, objects may not be held in full, intimate contact.
This lecture is a review of what we have learned over the past twenty or so years about all kinds of frictional contact, and when they give rise to ‘fretting’ and potentially fatigue cracks.