This research develops the understanding of fatigue crack growth in stage I for "load" control. Copper single crystals are selected as the specimen material because of the well-categorized behavior of the material under prior strain control experiments. Dislocation substructure stability and strain partitioning are examined under load control testing. Considerations include how variable loading influences the development of local strain and Stage I crack growth. The results will be used to form a model of damage accumulation for estimating fatigue lifetimes.
