Abstract: The fatigue test for a full scale fighter wing was carried out under simulated condition in order to examine its fatigue strengrlh. In the test, the aluminium alloy lug, which joins the wing and the fuselage, failed at the boundary of lug hole parallel to the fuselage. The fracture surface was observed by optical and scanning electron microscopes. There were widespread scars and extruded debris in the lug mated with a steel bushing. In the area of initial crack, wear was particularly obvious and serious and the crack origin caused by wear scars was observable directly. According to the condition of the stress and strain suffered by the lug, it is clear that fretting occured between the lug hole and the bush lug surface. The lug fracture, therefore, belongs to fretting fatigue fracture. A model illustrating the mechanism of the crack origin in fretting fatigue in the joining lug has been presented.

Key words: fretting, fretting wear, fretting fatigue, aluminium alloy, lug