Initiation and propagation of fretting fatigue cracks

Abstract Fretting fatigue tests of a carbon steel were carried out. Fatigue cracks were measured by means of electrical resistance and observed with a scanning electron microscope. The mechanism of fretting fatigue failure is discussed from the experimental results. Small fatigue cracks are initiated early in life and some grow to be propagating cracks. Cracks grow to a given depth by tangential stress combined with repeated stress and then propagate with repeated stress alone, causing a knee point in the propagation curve. Fretting fatigue damage is saturated in the first 20–25 % of life which coincides with the knee point. The condition of non-propagating cracks is also known.