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SMALL FATIGUE CRACK GROWTH BEHAVIOUR UNDER TWO STRESS LEVEL MULTIPLE LOADING
Author(s) -
Tokaji Keiro,
Ando Zenji
Publication year - 1984
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.1460-2695.1984.tb00409.x
Subject(s) - materials science , crack closure , amplitude , paris' law , growth rate , stress intensity factor , structural engineering , constant (computer programming) , stress (linguistics) , composite material , drop (telecommunication) , stress concentration , fatigue limit , metallurgy , fracture mechanics , mathematics , geometry , engineering , physics , telecommunications , linguistics , philosophy , quantum mechanics , computer science , programming language
Small fatigue crack growth behaviour in a low alloy steel was investigated under two stress step multiple loading in which the secondary stress was below the fatigue limit. Crack growth rates were presented in terms of a stress intensity factor and compared with data obtained under constant amplitude loading. In the higher Δ K region, crack growth rates increased monotonously with increasing Δ K even though the stress level was below the fatigue limit, and tended to be lower than those for constant amplitude loading. In the lower Δ K region, cracks showed a complicated behaviour, that is, an initial high growth rate was observed followed by an arrest or a drop to a minimum value and then a gradual increase. The average crack growth rates per cycle at both primary and secondary stresses in each block were approximately consistent with the da/dn ‐Δ K relation for constant amplitude loading. A suggestion for the prediction of crack growth life is given.