Abstract:

The concept of cyclic J integral Δ J * path proposed by the authors was briefly illustrated. In order to study the behavior of plastic strain fatigue crack growth (PSFCG) in the high strain zone of the notch , the constant amplitude PSFCG tests with six R ratios were performed on the single edge elliptical notch crack plates(SENCP) fabricated from 16MnR steel, while Δ J * path was calculated employing the material stress strain relation under the PSFCG from the elastic plastic finite element method. According to these experiment results, Δ J * path can be employed as a parameter predicting the PSFCG rate in the notch, and the d a /d N vs. Δ J * path relation for PSFCG is consistent with the Paris equation of the same material obtained by elastic stress fatigue crack growth test carried on the standard specimen, except that the Δ J * path was used in terms of the Δ K through Δ J * path =Δ K 2/E .

Key words: strain fatigue crack growth, cyclic J-integral $J * path, notch crackplates