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SHORT CRACKS AND LIFETIME OF A NORMALIZED CARBON STEEL UNDER CYCLIC BLOCK LOADING
Author(s) -
Bomas H.,
Linkewitz T.,
Mayr P.
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.tb00968.x
Subject(s) - materials science , block (permutation group theory) , composite material , cyclic stress , crack closure , paris' law , constant (computer programming) , carbon fibers , carbon steel , fracture mechanics , structural engineering , geometry , mathematics , composite number , engineering , corrosion , computer science , programming language
— The behaviour of short cracks and the lifetime of unnotched specimens of a normalized medium carbon steel is observed under constant cyclic loading and under cyclic block loading with changing mean stresses. The greatest part of the life is covered by the growth of short fatigue cracks. During cyclic block loading, the length of the loading blocks has a marked influence on the crack density and the lifetime of the specimens. Short blocks lead to high crack densities and low lifetimes. This effect can be explained by a short crack growth model which takes into account the crack arrest before microstructural barriers and crack linking in the case of high crack densities. The lifetimes for cyclic block loading are calculated on the base of the constant level data and found to be in good agreement with the measured lifetimes.