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A unification of small‐ and large‐crack growth laws
Author(s) -
Hamm Richard W.,
Johnson W. Steven
Publication year - 1999
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 - 10.1046/j.1460-2695.1999.t01-1-00149.x
Subject(s) - crack growth resistance curve , crack closure , paris' law , materials science , fracture mechanics , constraint (computer aided design) , mechanics , growth rate , crack tip opening displacement , stress concentration , fracture (geology) , stress (linguistics) , structural engineering , composite material , mathematics , geometry , engineering , physics , linguistics , philosophy
A generalized model enhancement is proposed to link small‐ and large‐crack growth laws. The enhancement is based on crack growth rate laws with crack tip plastic zone size formulations. Transition functions are used to transform small‐crack plastic zone sizes and crack growth law exponents to those predicted by linear‐elastic fracture mechanics. In doing so, influences on crack growth, e.g. constraint, crack aspect ratio and specimen geometry are accounted for. The applicability of the enhancement is directed toward instances where small cracks start from geometric features and grow through stress gradients to eventually become large cracks under nominal LEFM conditions. The enhancement is applied to the Wang model, and crack growth rate and fatigue lifetime predictions are made. The enhancement is shown to provide a good correlation to experimental results for Ti–6Al–4V under various maximum stresses at a stress ratio of R = 0.4.