On the use of NASGRO software to estimate fatigue life under constant and variable amplitude loadings in aluminum alloy SAE-AMS 7475-T7351

Abstract This paper uses several fatigue life prediction models implemented in the NASGRO program in order to predict the behavior of cracks on constant amplitude and variable amplitude loads. The experimental data consist of an aeronautical aluminum alloy SAE-AMS 7475-T7351. In the cases of constant loading amplitude (CAL) C(T) compact test specimens were used and M(T) type specimens were used in variable load amplitude casings (VAL). With respect to the constant amplitude data the fatigue growth rates and consequently the parameters of the Paris equation and the KIC values were obtained with the simulations. In this way the obtained values were satisfactory having good correlations. Regarding VAL the calibration parameters for each of the interaction models were obtained for each of the charge spectrum which for this work were TWIST and FALLSTAFF spectrums and their mini versions. The NASGRO 4.0 program presented overall good forecasting results.