Spectrum Fatigue Testing and Small-Crack Life Prediction Analysis on a Coupon Similar to a Critical Design Detail of a CF188 Hornet Component

Abstract

Abstract Numerous studies have shown that small-crack methodology can be used to predict the total fatigue life of laboratory type (KT = 1 and 3) specimens under variable amplitude loading. Prior to investigating how well this fatigue life prediction capability could be extended to “real” aircraft structures, an intermediary step was taken where total fatigue life was predicted for a laboratory type specimen similar to a critical design detail in a fighter aircraft fuselage bulkhead. Using the small-crack analysis in the computer code called FASTRAN and assuming an initial crack size of 20 microns, the time to catastrophic failure of the test coupons was predicted to within 10% of the average test times.