A steel has the following monotonic and cyclic properties: yield strength σy = 1000 MPa, smooth bar fatigue limit, σe = 600 MPa, threshold stress intensity factor range, ?K0 = 6 MPa.
(a) Plot the approximate variation of the threshold stress for no crack growth ?σth as a function of the crack size a for this material. Assume plane strain conditions.
(b) Plot the approximate variation of the threshold stress intensity factor range for no crack growth ?Kth as a function of the crack size a under plane strain conditions
(c) What is the crack size above which characterization of fatigue crack growth using linear elastic fracture mechanics can be justified?