On the fretting fatigue behavior of the cold expanded Al alloy 2024-T3 plates

Cold expanded holed plates are widely used in bolted joints which are subjected to clamping force. Previous studies on the effect of clamping force together with cold expansion on the fatigue behavior of the bolted joints revealed that the size of cold expansion has great influence on the fatigue durability of these joints due to the increase of the possibility of fretting fatigue occurrence. For better understanding this phenomenon, it is necessary to have detailed information about the effect of cold expansion on frictional force evolution during fatigue loading and the resulting stress field around the stress concentration zone. Therefore, in this paper, fretting fatigue testing apparatus was designed and fabricated for conducting fretting fatigue tests on the cold expanded specimens. Moreover, finite element simulation was used for evaluation of the residual stress distribution due to cold expansion and its effect on the fretting fatigue behavior of the joint. SWT multiaxial fatigue parameter was engaged for comparing the fatigue durability of the test specimens. The obtained results indicated that the cold expansion process reduces the stress concentration effect near the hole edge while it increases the possibility of fretting fatigue occurrence by generating tensile residual stress at areas away from the hole edge.