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TRANSIENT FATIGUE CRACK GROWTH BEHAVIOUR FOLLOWING SINGLE OVERLOADS AT HIGH STRESS RATIOS
Author(s) -
Tsukuda H.,
Ogiyama H.,
Shiraishi T.
Publication year - 1996
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.1460-2695.1996.tb01023.x
Subject(s) - materials science , crack closure , stress (linguistics) , paris' law , stress concentration , structural engineering , transient (computer programming) , growth rate , composite material , crack growth resistance curve , ultimate tensile strength , stress intensity factor , fracture mechanics , metallurgy , mathematics , engineering , geometry , linguistics , philosophy , computer science , operating system
— Fatigue crack growth tests with constant amplitude loading and single overload have been performed on a long mode I crack in 2017‐T3 aluminium alloy at various stress ratios from 0 to 0.7. Two crack tip parameters of σ op and σ tt were evaluated using a finite element analysis for a growing crack under these loading conditions. The former is the crack opening stress and the latter is the applied stress level at which the stress at the crack tip becomes tensile. It was found that transient crack growth behaviour following single overloads at high stress ratios was significantly different from that at a low stress ratio: at higher stress ratios, following the application of the overload, there was a rapid retardation which was followed by an acceleration in growth rate and then a faster return to the steady state level at baseline loading. The experimentally observed transient post‐overload behaviour is discussed in terms of the two effective stress range ratios of U op and U tt , which are determined from σ op and σ tt , respectively. For the stress ratios and overload ratios studied, the results indicate that the changes in U tt with crack extension after the overload are reasonably consistent with the crack growth rate trends. The stress distribution at minimum applied stress would account for the transient changes in U tt .