Analytical Predictions of Fatigue Crack Growth in the Lower Plate of the F-111 Wing Pivot Fitting Fuel Flow Hole Number 58
Abstract
This report details a comparison of fatigue growth predictions for a fatigue crack in the lower plate of the F-111 Wing Pivot Fitting, adjacent to Fuel Flow Hole No 58. This is a known fatigue critical location and is designated as DI 86. Fatigue analysis using conventional fracture mechanics techniques and empirical retardation models performed by the manufacturer, Lockheed Martin Tactical Aircraft Systems (then General Dynamics), predicted a fatigue life of approximately 57,000 flight hours. An equivalent analysis was conducted using the analytical crack closure code, FASTRAN II, and this resulted in a life prediction of about 25,000 flight hours. Spectrum differences provide a partial explanation. A FASTRAN II analysis using a spectrum based on an in-flight strain measurement system known as AFDAS produced a shorter life again. Further work is underway to quantify the difference in the predictions due to spectrum differences, and that due to analysis techniques.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1998
- Accession Number
- ADA348395
Entities
People
- B. J. Murtagh
- K. F. Walker
Organizations
- Defence Science and Technology Group