Assessment of Damage Tolerance Requirements and Analyses: A User's Manual for Crack Growth and Crack Initiation Analysis: 'DAMGRO.'

摘要

A structural test program of typical aircraft structural configurations was conducted to assess the current Air Force damage tolerance design requirements defined in MIL-A-83444. The specimens, made of 2024-T3XX and 7075-T6XX, were subjected to randomized flight-by-flight spectra, representative of fighter/trainer and bomber/cargo type loading spectra, respectively, and to a constant amplitude loading spectrum. A total of two-hundred fifty-six specimens were tested. The test results were correlated with analytical predictions using crack growth and crack initiation methods. As a result of this study, recommendation is provided to the validity of MIL-A-83444, to develop guidelines for selection of critical crack locations, and to assess the state-of-the art analytical capabilities in predicting crack growth and crack initiation time. This report presents the user's manual of the computer program DAMGRO. This program has been developed in conjuction with this contract, and used to predict the crack growth and crack initiation of the structural test specimens. (Author)