Estimation Procedure for Determination of Fatigue Crack Propagation in Metal Alloys

Estimation of closure-corrected fatigue crack propagation (FCP) data in monolithic metal alloys was reported recently by the author, using a simple computational method. The quantity E√b, where E = the modulus of elasticity, and b, the dislocation Burgers vector, is used to define a stress intensity factor, corresponding to an FCP rate of b/cyc. The remainder of the FCP curve at higher FCP rates (where da/dN > b) is found to follow a relation of the form: da/dN = (ΔK/E)3(1/√b). Good agreement is found between computed FCP data and recently reported experimental test results for various aluminum, titanium, and steel alloys. Such computations allow for a rapid and inexpensive way to estimate the FCP response of metals under both long and short crack growth conditions.