Citation
Hammouda, M.M.I. (2011), "Discussion", International Journal of Structural Integrity, Vol. 2 No. 3. https://doi.org/10.1108/ijsi.2011.4362caa.002
Publisher
:Emerald Group Publishing Limited
Copyright © 2011, Emerald Group Publishing Limited
Discussion
Article Type: Discussion From: International Journal of Structural Integrity, Volume 2, Issue 3
Yasuaki Hashikura, Koji Takahashi, Yuji Miyazaki, Keiji Houjou, Kotoji Ando, (2010) “Overloading effect on the fatigue threshold stress intensity factor range (ΔKth) as a function of crack length in SUS316”, International Journal of Structural Integrity, Vol. 1 No. 1, pp. 43-51
The International Journal of Structural Integrity has published the
above paper in its first issue on pages 43-51. The paper presents useful
experimental results on the effect of overloading on the threshold stress
intensity factor range, ΔKth, in SUS316. In
discussing the above experimentally found effect, the authors have predicted
ΔKth by deriving a model, see equation (7),
based on the residual SIF, Kr, as given by equation
(5). Based on that model, ΔKth for a given
overload ratio, ∝, can be predicted as follows. The terminology used in
the paper will be adopted here together with the numbers given to the equations.
From equations (4) and (6), a/b=cos(πσOV/4σy).
The base load at the threshold condition is σth and, hence,
equation (5) becomes:
Then, equation (7) becomes:
The threshold SIF range is, then, given by the following expression:
With increasing α, there is a corresponding increase in 34σth and, hence, the term αsec(πασth/4σy) increases. Thus, equation (b) predicts an infinite value of ΔKth taking place at a certain value of α,=αc. Based on equation (b), αc is close to 2. With a value of α>αc equation (b) gives a negative ΔKth value. The paper reports experimental results for α much higher than αc.Mechanical Engineering Department, Al Azhar University, Cairo, Egypt
M.M.I. Hammouda