Effect of Fighter Attack Spectrum on Crack Growth
Abstract
The purpose of this program was to systematically evaluate the effect of variations in flight stress spectra on crack propagation using current analysis techniques in conjunction with experimental correlations. Over 100 spectra variations were generated, derived from four baseline load factor spectra. The spectra variation types considered were (a) Reordering of loads within a mission, (b) Sequence of missions, (c) Mission mix, (d) Individual length, (e) High and low load truncation, (f) Compression loads, (g) Exceedance curve, (h) Coupling of peaks and valleys, (i) Test limit stress. Crack growth was predicted for each baseline spectrum and spectra variation prior to test with the exception of tests for one baseline spectrum. The generalized Willenborg Model was the primary method of crack growth analysis. Additionally, predictions were made using a closure model based on analyses of crack surface contact. Three constant amplitude and thirty spectrum tests were performed to verify the predictions of the analysis methods, to evaluate the effects of spectra variations, and to provide data useful for defining guidelines for structural verification of future aircraft. Spectrum variations shown to have the greatest impact on crack growth life are those involving modifications of the maximum peak stresses. The experimental data was evaluated and summarized, and recommendations and guidelines were developed for deriving spectra for multi-mission tactical fighter aircraft.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1977
- Accession Number
- ADA042369
Entities
People
- C. R. Saff
- H. D. Dill
Organizations
- McDonnell Aircraft Corporation