Fretting fatigue behaviour of aluminium alloy 6061-T6 under plane bending

Fretting fatigue behaviour of Al-Mg-Si alloy 6061-T6 was studied at different cyclic stress levels under completely reversed plane bending conditions. Fretting behaviour of the alloy was assessed by comparing with the data generated under plain fatigue conditions concurrently. Fretting fatigue tests were carried out at different initial contact pressures of 150, 200, 250 and 290 MPa with a slip amplitude of 25 μm. Two stage sequential fatigue tests with different levels of fretting fatigue damage in the first stage followed by plain fatigue damage in the second stage were also carried out. The effect of fretting on fatigue life reduction was significantly high at low stress levels compared to that at high stress levels. The fretting fatigue life decreased with an increase in the contact pressure. The two stage fatigue tests indicated that fretting plays a critical role in the crack initiation stage rather than the crack propagation stage.