Accession Number : ADA311018

Title :   Micro-Structure in Particulate Media - A Lattice Type Approach and Its Validation.

Descriptive Note : Final rept. 1 Jul 93-30 Jun 96,

Corporate Author : ARIZONA UNIV TUCSON COLL OF ENGINEERING AND MINES

Personal Author(s) : Budhu, Muniram ; Frantziskonis, George ; Ramakrishnan, S.

PDF Url : ADA311018

Report Date : 27 JUN 1996

Pagination or Media Count : 249

Abstract : The objective of this research is to develop a lattice type model for describing the micro mechanical behavior of particulate media. In this model, each particle is replaced by a lattice and the interactions between each particle and its neighbors are described through contact nodes. An assembly of particles is then transformed into a two dimensional truss. Bars connecting the contact points of the particles represent the particles and constraints are prescribed at the nodes of the truss to describe sliding, bonding and rebonding. When a deformation mechanism develops, the truss becomes a pin jointed frame to derive the kinetics of the assembly. The mechanics, formulation and numerical implementation of the lattice type model are depicted. Numerical tests comprising two dimensional assemblies of disks, arranged as very loose and very dense packings, were subjected to simple shear deformation. The results show the distribution of the internal forces, the load and displacement paths, and the deformation mechanisms. Although the packings were homogenous and isotropic, the applied simple shear strains result in inhomogeneous deformation. Deformation takes place through chains or clusters of particles. Photoelastic experiments on disks, presented in Part II of this report, gave results that are in agreement with the predictions from the lattice type model. The lattice type model is conceptually simple but has some powerful features (for examples, initial imperfections, anisotropy, and particle crushing can be considered) that can provide significant insights into the micro mechanical behavior of particulate media.

Descriptors :   *NUMERICAL ANALYSIS, *ROCK MECHANICS, *LATTICE DYNAMICS, SHEAR PROPERTIES, MICROSTRUCTURE, TWO DIMENSIONAL, DEFORMATION, DISPLACEMENT, NODES, CLUSTERING, ANISOTROPY, PARTICULATES, KINETICS, ASSEMBLY, PHOTOELASTICITY, CRUSHING.

Subject Categories : Geology, Geochemistry and Mineralogy
      Numerical Mathematics

Distribution Statement : APPROVED FOR PUBLIC RELEASE