Experimental and numerical investigation on the fretting fatigue behavior of cold expanded Al-alloy 2024-T3 plates

Abstract

In this paper, fretting fatigue behavior of the cold expanded plates have been studied both numerically and experimentally. For this purpose, fretting fatigue testing fixture has been designed and fabricated for simulating fretting condition on the holed plates. The test specimens were cut from aluminum alloy 2024-T3 plate and have been cold expanded at two sizes of 1.5% and 4.7% before fretting fatigue tests. Two values of cyclic longitudinal load and normal contact force were applied to the specimens. The results of the experiments revealed that applying high level of cold expansion affects the frictional force on the contact interface. Moreover, cold expansion makes the fretting fatigue phenomenon to be likely to occur at locations away from the hole. The obtained numerical results indicated that tensile residual stress would be generated at areas away from the hole edge by cold expanding the holes. During fatigue loading, the tensile residual stress is superimposed to the tensile fatigue load which intensifies the stress severity and reduces the fretting fatigue life. The intensity of the tensile residual stress increases by increasing the level of cold expansion. As a result, lower fretting fatigue life is expected on higher size cold expanded plates.