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ON THE OVERLOAD INDUCED FATIGUE CRACK PROPAGATION BEHAVIOR IN ALUMINUM AND STEEL ALLOYS
Author(s) -
Vecchio R. S.,
Hertzberg R. W.,
Jaccard R.
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.tb00188.x
Subject(s) - materials science , crack closure , aluminium , ultimate tensile strength , fracture mechanics , plane (geometry) , stress intensity factor , plane stress , composite material , metallurgy , structural engineering , geometry , mathematics , finite element method , engineering
The overload induced fatigue crack propagation behavior of several aluminum and steel alloys was examined as a function of the baseline stress intensity factor range (δ K b ). In order to gain a clearer understanding of the parameters which influence the cyclic delay phenomenon, under both plane strain and plane stress conditions, tests were conducted at δ K b values ranging from the near threshold regime to high δ K levels approaching fast fracture. Large amounts of overload induced cyclic delay (˜100,000 cycles) were observed at both high and low δ K levels (provided the plastic zone size/thickness ratio and plastic zone size/grain size ratio approached unity, respectively) with significantly less delay occurring at intermediate δ K values. All alloys examined exhibited this type of delay behavior which can be described by a “U‐shaped” plot. The delay phenomenon at high δ K b levels under plane stress conditions was attributed to increased crack closure associated with large tensile displacements in the wake of the advancing crack. At low δ K b levels increasing cyclic delay was attributed to an increased effective overload ratio as δ K approached δ K th .