Incorporation of Half-Cycle Theory Into Ko Aging Theory for Aerostructural Flight-Life Predictions
Ko, William L. and Tran, Van T. and Chen, Tony (2007) Incorporation of Half-Cycle Theory Into Ko Aging Theory for Aerostructural Flight-Life Predictions. Technical Report NASA/TP-2007-214608, Research and Engineering, NASA Dryden Flight Research Center.
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Abstract
The half-cycle crack growth theory was incorporated into the Ko closed-form aging theory to improve accuracy in the predictions of operational flight life of failure-critical aerostructural components. A new crack growth computer program was written for reading the maximum and minimum loads of each half-cycle from the random loading spectra for crack growth calculations and generation of in-flight crack growth curves. The unified theories were then applied to calculate the number of flights (operational life) permitted for B-52B pylon hooks and Pegasus® adapter pylon hooks to carry the Hyper-X launching vehicle that air launches the X-43 Hyper-X research vehicle. A crack growth curve for each hook was generated for visual observation of the crack growth behavior during the entire air-launching or captive flight. It was found that taxiing and the takeoff run induced a major portion of the total crack growth per flight. The operational life theory presented can be applied to estimate the service life of any failure-critical structural components.
| EPrint Type: | NASA Technical Publication |
|---|---|
| Keywords: | B-52B airplane, Crack growth curves, Fatigue cracks, Half-cycle theory, Hyper-X launch vehicle, Operational life predictions, Pegasus®, Structural aging theory, X-43 Hyper-X research vehicle |
| Subjects: | Aircraft/Project: B-52 Aircraft/Project: X-43A Hyper-X Aircraft/Project: Pegasus (31 - 39) Engineering: (39) Structural Mechanics |
| ID Code: | 1332 |
| Deposited On: | 30 January 2007 |
| Additional Information: | 88 pages. Ko, Tran, and Chen, NASA Dryden Flight Research Center. |
