Dissertations, Theses, and Capstone Projects

Date of Degree

2-2015

Document Type

Dissertation

Degree Name

Ph.D.

Program

Physics

Advisor

Mark D. Shattuck

Advisor

Corey S. O'Hern

Subject Categories

Physics

Keywords

Delaunay Triangles, Granular, Information Theory, jammed, packings, vibrations

Abstract

We use simulations of soft bidisperse disks to determine the properties of jammed packings and investigate the statistical mechanics of these systems. We have created a novel method for the classification of structural subunits of a packing and to calculate relevant physical quantities. The classification scheme is based on a 20 type decomposition of the Delaunay triangles extracted from the centers of the particles. Subunit frequencies are determined from geometrical properties and used to calculate the important macroscopic system quantities co-ordination number, packing fraction, and pressure. These relationships suggest that microscopic particle geometry plays an important role in observed macroscopic behavior. In addition, we investigate the contact network evolution during elastic perturbation. We predict the fraction of time a contact will be broken from the the inter-particle potential before perturbation. We explore the energy regions, below particle rearrangement, where our prediction is valid and discuss a physical mechanism for this behavior based on the exchange of potential and kinetic energy between particles.

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