National Aeronautics and Space Administration (NASA)
Published: 2018-07-10
Total Pages: 36
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A new second-order theory was developed for predicting the service lives of aerospace structural components. The predictions based on this new theory were compared with those based on the Ko first-order theory and the classical theory of service life predictions. The new theory gives very accurate service life predictions. An equivalent constant-amplitude stress cycle method was proposed for representing the random load spectrum for crack growth calculations. This method predicts the most conservative service life. The proposed use of minimum detectable crack size, instead of proof load established crack size as an initial crack size for crack growth calculations, could give a more realistic service life. Ko, William L. and Monaghan, Richard C. and Jackson, Raymond H. Armstrong Flight Research Center RTOP 505-63-40...