Fatigue-Crack Growth Behavior of C-5A Wing Control Points.
Interim rept. 20 Oct 72-20 Oct 73,
BATTELLE COLUMBUS LABS OHIO
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An extensive fatigue-crack-growth analysis was conducted to evaluate the flight-by-flight crack-growth behavior of the C-5A wing structure control points. Fourteen missions of flight stress spectra and several mission mixes were considered in the analysis. Both linear and retarded nonlinear concepts of fatigue-crack growth were analyzed with the AFFDL CRACKS II computer program with the Willenborg effective stress retardation model. The model was found to adequately predict laboratory flight-by-flight test data. Fatigue-crack-growth behavior was found to be sensitive to stress increments as derived from a constant exceedance curve, mission severity, and stress sequence. The results of the flight-by-flight analysis for each of the wing structure control points defined the most critical locations for inspection purposes. In addition, fatigue-crack behavior was found to be very sensitive to mission stress spectra and mission mix.
- Transport Aircraft