Fretting is the micrometer-level relative movement between contacting surfaces that can
lead to fretting fatigue and fretting wear in practical connections in machine components.
Fretting has a clear tendency to nucleate cracks that can continue to grow as a result of the
cyclic loads in a component, leading to premature failure. The lack of fundamental
knowledge of the fretting mechanism and a universal model poses challenges for the design
of modern machine components having contacts under high loading.