Fatigue crack propagation:
If it is assumed that no plastic deformation occurs around crack tip and law of fatigue crack propagation for place of above Example is da/dN = 10^{- 8} (Δ K_{I eff })2.0 mm/cycle , find after how many cycles the plate will fracture.
Solution
Δ K I = ΔK _{I eff} because there is no plastic deformation in crack tip neighbourhood.
a_{c} = 146.14 mm, a_{i} = 35 mm from above Example .
or, Nf =2´10^{4 }ln ( ac/ ai) = 2´10^{4} ln (146.14/35)
or, N f = 2´10^{4 }ln (4.175) = 28584 cycles