Practical Theories for Service Life Prediction of Critical Aerospace Structural Components

Ko, William L. and Monaghan, Richard C. and Jackson, Raymond H. (1992) Practical Theories for Service Life Prediction of Critical Aerospace Structural Components. Technical Report NASA TM-4354, Research Engineering, NASA Dryden Flight Research Center.

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Abstract

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 cycles 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.

EPrint Type:	NASA Technical Memorandum
Keywords:	Fracture mechanics, Half-cycle theory, Random stress cycles, Service life prediction
Subjects:	Aircraft/Project: Miscellaneous (31 - 39) Engineering: (39) Structural Mechanics
ID Code:	274
Deposited On:	26 July 2004
Additional Information:	28 pages. Errata (March 1992) Figures 3, 8 and 9 (pages 17/18 and 21/22) have been corrected and substituted herein.