Explicit cyclic J-integral expressions for low-cycle fatigue modeling of plane stress crack problems
✍ Scribed by Faisal H. Al-Sugair
- Publisher
- Elsevier Science
- Year
- 1992
- Tongue
- English
- Weight
- 652 KB
- Volume
- 43
- Category
- Article
- ISSN
- 0013-7944
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✦ Synopsis
Low-cycle fatigue crack propagation has been modeled successfully by an equation employing the cyclic J-integral, A/. The use of this equation in practice is hindered by the difficulty of calculating AJ. A load-deflection hysteresis diagram must be obtained to estimate its value for several points on the crack growth curve. Several approximations have been presented to estimate the J-integral for monotonic crack growth, of which the work of Shih and Hutchinson seems to be the most promising. In their work they present fully plastic estimates of the J-integral, which they fit to full numerical calculations obtained using the finite element method.
In this paper, the fully plastic estimates of the J-integral given by Shih and Hutchinson for Ramberg-Gsgood type materials in plane stress conditions are extended to arrive at an equation for calculating the J-integral range, AJ. The estimates are fitted to ex~rimentally obtained values of AJ and a correction term is found. The new estimates are used to correlate low-cycle fatigue crack growth rates.
The results indicate that the estimates are quite accurate and provide a relatively easy method for estimating AJ. Also, the values calculated using this method correlate with low-cycle fatigue crack growth data quite well, and thus provide a tool for low-cycle fatigue modeling. In addition, the whole procedure employing AJ lends itself to high-cycle fatigue problems where AJ reduces to the stress intensity factor, AK, used for high-cycle fatigue.