|dc.description.abstract||Understanding the elastic-plastic response of polycrystalline materials is an
extremely difficult task. A polycrystalline material consists of a large number of crystals
having different orientations. On its own, each crystal would deform in a specific manner.
However, when it is part of a polycrystalline aggregate, the crystal has to ensure
compatibility with the aggregate, which causes the response of the crystal to change.
Knowing the response of a crystal enables us to view the change in orientation of the
crystal when subjected to external macroscopic forces. This ability is useful in predicting
the evolution of texture in a material. In addition, by predicting the response of a crystal
that is part of a polycrystalline aggregate, we are able to determine the free energy of
each crystal. This is useful in studying phenomena like grain growth and diffusion of
atoms across high energy grain boundaries.
This dissertation starts out by presenting an overview of the elastic and plastic
response of single crystals. An attempt is made to incorporate a hardening law which can
describe the hardening of slip systems for all FCC materials. The most commonly used
theories for relating the response of single crystals to that of polycrystalline aggregates
are the Taylor model and the Sachs model. A new theory is presented which attempts to
encompass the Taylor as well as the Sachs Model for polycrystalline materials. All of the
above features are incorporated into the software program "Crystals".||en