Dynamic Treatments of Fatigue Crack Growth

Abstract

The instability of dislocation emission from the crack tip under applied stress was theoretically annalysed. Combining the results with those by computer simulation of dynamics of dislocation groups emitted from the crack tip, the micro-and-macro fracture dynamics approach has been used for the problem of fatigue crack growth.
The theoretical treatment is valid in both the blunting-resharpening model and the coarse slip model either under Mode I or Mode II loading including body-centered cubic metals and face-centered cubic metals as well.
The results explains the experimental characteristics of fatigue crack growth unifiedly, such as, stress intensity factor, temperature and frequency dependence of crack growth rate.
It was also shown that the micro-and-macro fracture dynamics approach proposed can be applied to the case of elastic-plastic cracking.