A modified wheeler model to improve predictions of crack growth following a single overload

This paper modifies the Wheeler retardation concept to improve the accuracy of crack growth predictions after a single overload. This modification is primarily based on the number of delay cycles, N-d, and on the overload aff ected crack length, a(d). N-d is used to calibrate the Wheeler exponent, m, and a(d) is employed to assess the effective overload plastic zone size. I n addition, the regression equations for m and a(d) are established in term s of the overload ratio OLR. The modified Wheeler model together with these equations performed well in reproduction of the actual crack growth behavi or in 5083-O aluminum alloy. All predictions of the number of delay cycles were within a factor of 1.1 of the experimental observations.