Crack Behavior of the Aluminum Alloy 2024 Under Fretting Conditions

The initial stage of fretting fatigue crack growth is significantly influenced by tangential force induced by fretting action along the contact surface where a mixed-mode crack growth is involved. Fretting crack behavior of aluminum alloy 2024 was studied, taking into account the problem of contact asperities. Finite element was used for the determination of the stress field near the contact surface and the stress intensity factor. The results showed that tensile stress maxima are situated at the trailing edge of the contact zone. Experimental results showed that the crack initiates from the trailing edge of the contact zone too. The crack extension angle was calculated and compared with experimental results at different normal loads. The stress intensity factor increased with increasing friction. The crack initially grows in combined mode I and II before deflecting to mode I plane. Delamination, one of the wear mechanisms, has been observed in our experiments too.