Modeling the elastic and plastic response of single crystals and polycrystalline aggregates

by Patwardhan, Parag Vilas

Abstract (Summary)
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".

Bibliographical Information:

Advisor:Srinivasa, Arun; Karaman, Ibrahim; Whitcomb, John

School:Texas A&M University

School Location:USA - Texas

Source Type:Master's Thesis

Keywords:simulation modeling crystals polycrystals polycrystalline elastic plastic deformation energy free


Date of Publication:12/01/2003

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