Computation of Effective Fatigue Thresholds Based on a New Concept of Crack Closure
A new theoretical concept of crack closure under plain strain was applied to assess the effective fatigue threshold under various loading condition for selected aluminium and titanium alloys of different microstructures. The concept is based on the long-range effect of geometrically necessary dislocations remaining in the wake of propagating fatigue cracks. Calculated threshold values FKeff,th for 7475 aluminium alloy are about 1.9 MPa.m1/2 (in vacuum) and 1 MPa.m1/2 (in air), and about 2.5 MPa.m1/2 and 3.3 MPa.m1/2 for c-titanium and Ti-2.5%Cu, respectively. All calculated values are nearly independent on both the microstructure and the applied stress ratio and they are in a good agreement with experimental data.
M.H. Aliabadi, Qingfen Li, Li Li and F.-G. Buchholz
J. Horníková et al., "Computation of Effective Fatigue Thresholds Based on a New Concept of Crack Closure", Key Engineering Materials, Vols. 324-325, pp. 803-806, 2006