抄録
The concepts of crack closure and J integral were applied to analyze the effect of pre-strain on fatigue crack growth in low-carbon steel, which was monotonically pre-stretched to 15 percent plastic strain and cyclically pre-strained to about the half of the total fatigue life. The treatment of pre-strain did affect considerably the relation between the growth rate and the stress intensity factor. On the other hand, no significant effect was found when the rate was correlated to the effective range of stress intensity factor in the cases of small scale yielding. For both small and large scale yielding situations in all cases of pre-straining treatments examined, the growth rate was found to be a single-valued function of the crack tip opening displacement range or the J integral range. The mechanistic aspect of fatigue crack growth mechanisms was discussed based on the experimental results.
