ANALYSIS OF FRETTING CONDITIONS IN PINNED CONNECTIONS

A 2-dimensional, finite element model of a pinned connection, involvin g AA7075-T6 aluminum alloy sheet and aluminum and steel pins, is used to evaluate the local mechanical parameters that control fretting wear damage. These include the contact pressure, the slip amplitude, the t ensile stress parallel to the hole interface and a fretting wear (F-1) and fretting fatigue (F-2) parameter. The connection is subjected to cyclic loading with a peak nominal stress of sigma=125 MPa and R=0.1. The dimensions and constraints of the model approximate those of multi -riveted panels. Values of interference in the range 0-2% interference , and 2 values of the coefficient of friction, mu=0.2 and mu = 0.5, ar e examined. The variations of the mechanical parameters with angular p osition about the hole are defined. Peak contact pressures in the rang e p = 500-600 MPa are obtained at the pin-bore interface. The slip amp litudes in the range 2 mu<delta<20 mu m, and circumferential tensile s tresses as high as sigma approximate to 100 MPa, are produced in regio ns where the contact pressure is generally above p=400 MPa. The peak v alues of the fretting wear parameter, 0.3 kPa m<F-1<3 kPa m, coupled w ith small slip amplitudes and specific wear rates cannot account for s ignificant material loss in the stiff model connection examined here. However, the relatively large fretting fatigue parameter values, 6x10( 10) Pa m<F-2<70x10(10) Pa m, could promote early fretting fatigue fail ure in the absence of interference.