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A unified model for the fatigue crack growth rate in variable stress ratio
Author(s) -
SHAHANI A. R.,
KASHANI H. MOAYERI,
RASTEGAR M.,
DEHKORDI M. BOTSHEKANAN
Publication year - 2009
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.1460-2695.2008.01315.x
Subject(s) - crack tip opening displacement , constant (computer programming) , paris' law , materials science , aspect ratio (aeronautics) , structural engineering , fracture mechanics , mathematical analysis , crack closure , mechanics , mathematics , composite material , physics , engineering , computer science , programming language
The paper presents four equations for Fatigue Crack Growth Rate (FCGR) description taking into account Δ J , ΔCTOD, ΔCMOD and Δ K . CT specimens made of steel were tested for different values of stress ratio ( R ) by Δ P = constant method. The influence of R ‐ratio has been studied on crack propagation and crack initiation region. The experimental results show that Δ J and ΔCTOD, contrary to Δ K and ΔCMOD which are constant in R ‐ratio variations, vary with the variations of R ‐ratio in the range R = 0.3–0.6. Therefore, there is no need to enter R parameter directly in the well‐known Paris equation if Δ J or ΔCTOD parameter is used instead of Δ K in this equation. The constants of these equations are independent of loading unlike the constants of Paris equation.