Basic Studies in Finite Plastic Deformation of Metal Polycrystals and Crystalline Aggregates

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This research has as its objectives, advances in understanding and analysis of large plastic deformation of crystalline materials and improvements in predictive capability of bi-crystal and crystalline aggregate models. Two principal lines of investigation are planned: (1) analysis of texture formation in f.c.c. crystalline aggregates using experimentally-based hardening rules, including application of the theory of minimum plastic spin to resolve the long-standing non-uniqueness problem in rate-independent, uniform distortion models; and (2) detailed analysis of nonuniform shearing and lattice rotation in bi-crystals in the channel die compression test, again making use of minimum plastic spin and including comparison with experimental observations and data. In addition, studies will be initiated for the development of improved crystalline slip constitutive equations, well-founded in experiment, that include rate-dependent as well as deformation- dependent elastic ranges. Successful accomplishment of these interrelated investigations would substantially contribute to greater understanding of and accurate predictive capabilities for finite distortion and texture evolution in metal polycrystals and aggregates.