CRITICAL EXAMINATION OF FATIGUE THRESHOLDS

摘要

In general both peak stress intensity K_(max) and cyclic stress intensity ΔK are necessary for the propagation of a fatigue crack. The corresponding threshold values depend on the nature of the governing dislocation processes. These two fundamental parameters relate primarily to minimum stress required for dislocation generation, and the minimum reverse stress necessary for resharpening the crack, respectively. Therefore in the general analysis, there is a unified framework for existence of both K_(max) and ΔK thresholds, and no apriori reason for the two to be identical.