Digital Repository, ICF12, Ottawa 2009

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Experimental estimation of fatigue crack growth rate and study of stress ratio effect in thin aluminium alloy plates
A.R. Shahani, H. Moayeri Kashani, M. Rastegar, M. Botshekanan Dehkordi

Last modified: 2013-05-03


Fatigue crack growth rate (FCGR) is expressed in terms of ÄJ (cyclic J-integral),
ÄCTOD (cyclic crack tip opening displacement) and ÄCMOD (cyclic crack
mouth opening displacement) instead of ÄK (cyclic stress intensity factor) in the
well-known Paris equation. Conducting several tests on CT specimens made of
aluminium alloy with specific chemical composition and having 2.9mm thickness
according to standard test method ASTM E647, the proposed model is examined.
The experimental results show that ÄJ and ÄCTOD, contrary to ÄK and ÄCMOD
which are constant in R-ratio variations, vary with the variations of R-ratio in the
range R=0.3 to R=0.6. Therefore, there is no need to enter R parameter directly in
the well-known Paris equation if ÄJ or ÄCTOD parameter is used instead of ÄK
in this equation. The constants of these equations are independent of loading
unlike the constants of Paris equation. Finite element analysis is also performed
and the results are compared with the experimental results.

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