Predicting Fatigue Crack Retardation in 7150 Aluminum Alloy

摘要

The aim of this work is to evaluate the applicability of the Wheeler and Willenborgrnmodels to predicting fatigue crack growth retardation in a 7150 overaged aluminium alloy used asrnaircraft structural material. Constant amplitude loading was adopted for the fatigue tests making usernof CT specimens. Three different single tensile overloads were applied at a given crack lengthrnduring CA fatigue loading and crack growth rate da/dN versus the stress intensity factor range △Krnwas monitored, evidencing the retardation in crack propagation over an interval of crack length.rnThe results indicated that the fatigue life increases with the increase in the magnitude ofrnoverloading. The size of the delay zone as well as the retarded crack propagation rate werernpredicted by both the Wheeler and Willenborg models and then compared with the experimentalrndata. Finally, the results are presented and discussed focusing on the comparison between thernpredictions made by the two models in light of the experimental data.