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FATIGUE CRACK GROWTH OF Al 2024‐T3 UNDER LOW AMPLITUDE TWO‐STEP LOADING
Author(s) -
Mayer H. R.,
Stanzl S. E.,
Tschegg E. K.,
Schijve J.
Publication year - 1992
Publication title -
fatigue and fracture of engineering materials and structures
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.887
H-Index - 84
eISSN - 1460-2695
pISSN - 8756-758X
DOI - 10.1111/j.1460-2695.1992.tb01269.x
Subject(s) - amplitude , materials science , paris' law , fracture (geology) , intensity (physics) , surface roughness , growth rate , structural engineering , composite material , mechanics , crack closure , fracture mechanics , mathematics , optics , physics , engineering , geometry
— The significance of interaction effects has been studied in tests with a continuous repetition of blocks with low and high amplitude cycles under conditions characteristic for ultrasound fatigue. Significant retardation effects were observed. However, low‐intensity cycles, which according to a previous investigation might be harmless, did contribute to crack growth. Delayed retardation explains this observation. A fractographic analysis indicated the significance of surface roughness. Low‐amplitude cycles may induce a smoother fracture surface, and thus increase the crack growth rate at higher amplitudes. Accurate predictions are therefore problematic. For similar reasons, omitting numerous low‐amplitude cycles in random load experiments should be done with great care.