A numerical investigation on constant amplitude loading

The crack length a versus the number of loading cycles N is required by the designers for life predictions based on the damage tolerance philosophy. The objective of this work is to describe a computational method for determ-ination of errors which occur if the fatigue crack growth is computed on the basis of an assumed crack extension.
Calculations have been compared with cycle-by-cycle method of crack extension. It is shown that for assumed crack extension method to give meaningful results there is an
optimal value of assumed value of crack extension below and above which fatigue crack growth rate (FCGR) calcul-ations do not agree with experimental data. There is an excellent agreement between optimal value of crack exten-sion based life predictions of test components and experi-mental data available in the literature.