Comments on Fatigue Crack Growth Under Mixed Modes I and III and Pure Mode III Loading

Some features of fatigue crack growth under pure Mode III and mixed Modes I and III loading were examined, including two cases where the Mode III displacements are not proportional to the Mode I displacements. Information obtained under nominally elastic conditions for various commercial alloys was reanalyzed and discussed in the light of theoretical considerations to see whether consistent patterns of behavior could be identified. Despite some inconsistencies and anomalies it was found that a reasonably consistent pattern of behavior was beginning to emerge. In particular a tentative upper bound for the rate of fatigue crack growth was identified, but it does not apply to slant crack growth in thin sheets.