Evolving Multiscale Deformation and Damage in Polycrystals
Final rept. 17 May 1999-16 May 2003
GEORGIA INST OF TECH ATLANTA SCHOOL OFMECHANICAL ENGINEERING
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The goal of this program was to develop incompatibility-based concepts for linking the kinematics of finite plastic deformation and failure modes across multiple length scales in crystalline and polycrystalline metallics. To do so, we consider the variation through the microstructure of thermodynamic driving forces for damage initiation and growth associated with strong lattice rotations and strain energy localization near heterogeneities such as second phase particles or grain boundary triple points. Emphasis is placed on multiple length scale modeling of plastic deformation and damage for micro-, meso and macro-levels. Such models are novel and much more inclusive than traditional continuum models of underlying microstructural features. Contributions of entities such as cracks, voids or shear bands are treated in a consistent, multiscale manner within this kinematical framework. We combine the work on fundamentally new decompositions of the finite deformation gradient for plasticity and damage with computational simulations and measurement of sub-grain scale stretch and rotation fields to validate and understand implications. Experiments are performed on both polycrystalline pure copper as well as copper doped with antimony to promote intergranular fracture. Novel methods of measurement down to scale of 5-10 microns are developed for curved specimens using lithographic grids.
- Metallurgy and Metallography