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

本研究的目标是在理解和分析晶体材料的大塑性变形方面取得进展，并提高双晶和晶体集合体模型的预测能力。本研究计划开展两个主要研究方向：(1)利用基于实验的硬化规则分析氟化碳晶体聚集体的织构形成，包括应用最小塑性自旋理论来解决速率无关的均匀畸变模型中长期存在的非唯一性问题；(2)详细分析了通道模压缩试验中双晶的不均匀剪切和晶格旋转，再次利用最小塑性自旋，并与实验观察和数据进行了比较。此外，将开始研究改进晶体滑移本构方程的发展，在实验中有充分的基础，包括速率相关以及变形相关的弹性范围。这些相关研究的成功完成将大大有助于更好地理解和准确预测金属多晶和聚集体的有限变形和织构演变。

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.