Crack Behavior in the Early Stage of Fretting Fatigue Fracture

The initial stage of fretting fatigue crack growth is significantly influenced by tangential force induced by fretting action along the contact surface, where both mix-mode crack growth and short crack problems are involved. A finite element procedure for the determination of the stress field near the contact surface with friction and of stress intensity factors for fretting fatigue cracks has been introduced. Fretting fatigue tests at the stress amplitude lower than the fretting fatigue limit and mix-mode crack growth tests have been carried out. The influence of Mode II component of stress intensity factor, which accelerates the fatigue crack growth rate, is more significant for shorter and inclined cracks. The fretting fatigue cracks observed at the fretting fatigue limit conventionally defined at 107 cycles were not arrested but continued propagating. Non-propagating cracks were observed at stress amplitudes much lower than the conventional fretting fatigue limit.