Alldraet
-Thef&urepraxgses of micro or small cracks may behave differently as suggested by ~ntinu~ medium mechanics. A minimum fracture unit should exist for a real ~1~ material, for any part sruaher than this unit fracture mechanics caunot be applied. Based on this idea, the elastic stress and stress intensity factor range are expressed in terms of an equivalent fracture unit which is conducted with a through-thickness crack. Theoretical predictions on notched fatigue limits of crack initiation and crack propagation are derived and discus&. Good agreement between predicted values and experimental results has been achieved. equivalent fracture unit non-propagating crack length notch radius notch depth number of a+ wetGent in ur equation stress inundation factor stress intensity factor range threshold AK for a long crack effective threshold AK nominal net stress at a notch local stress m y direction at a notch average stress of up over a series of o* plain fatigue limit of uniaxial loading notched fatigue limit of uniaxial loading theoretical fatigue limit of crack initiation theoretical fatigue limit of crack propagation threshold AK for non-propagating cracks threshold AK for a* at the surface (n = 0)