fretting
Fretting is a type of wear and potential fatigue damage in the contacting surfaces of metallic parts exposed to small repeated movements. It commonly develops in static joints or assemblies subjected to vibration or alternating loads and results in surface degradation over time. Detecting such damage is often very challenging until complete failure is evident.
Key Features:
- Surface Wear by Micromotions: Small-amplitude reciprocating relative motion between two surfaces under load produces wear particles and surface roughening.
- Fatigue Crack Initiator: By creating stress concentration, fretting zones become the likely initiation location for fatigue cracks, thereby compromising service life.
- Generation of Debris: Wear debris in the form of fine metallic particles and oxides can increase damage rate through abrasive actions.
Fretting can prove the bane of high-precision assemblies, from turbine blades to bolted joints and bearing interfaces where micro vibrations occur over very long periods of time.
The presence of fretting can lead to losses in performance, unplanned maintenance, or even structural failures. It can be prevented using surface coatings, design considerations, or controlled loading conditions, making it necessary for the engineer to recognize and address fretting early in both design and maintenance phases.