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Multiple mechanisms controlling fatigue crack growth
Author(s) -
SADANANDA K.,
VASUDEVAN A. K.
Publication year - 2003
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.1460-2695.2003.00684.x
Subject(s) - paris' law , crack closure , crack growth resistance curve , growth rate , trajectory , materials science , structural engineering , closure (psychology) , function (biology) , mechanics , fracture mechanics , mathematics , composite material , engineering , geometry , physics , economics , market economy , astronomy , evolutionary biology , biology
Recognizing that fatigue is a two‐parameter problem requiring two load parameters to define cyclic loads unambiguously, a unified approach has been developed to account for crack growth behaviour in terms of Δ K and K max . Since both driving forces govern the crack growth rate, any analysis based on either Δ K or K max will provide only partial information about the fatigue behavior of materials. It is shown that Δ K – K max plots and the associated crack growth trajectory maps reflect the basic mechanisms that contribute to crack growth in a material. These plots also provide a convenient basis to recognize the changes in the micromechanisms that can occur as a function of load ratio or crack growth rate, or both. Taking examples from the literature, crack growth trajectory maps are provided showing such changes in the governing mechanisms of crack growth. It is shown that the Δ K – K max approach is not an alternative to crack closure models, but it reflects the intrinsic material behaviour that must be understood before reliable crack prediction models can be developed.