Abstract/Details

Evaluation of discrete element analysis for the mechanics of granular assemblies


1996 1996

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Abstract (summary)

The micro-structural approach, which relates the mechanical behavior of a material to its micro-fabric and the properties of the constituent particles, is a more rational way of modeling the mechanics of granular materials. Within this approach is the numerical simulation method in the framework of the Discrete Element Method (DEM) of analysis. Instead of a continuum, DEM treats granular material as an assemblage of distinct particles, each governed by the laws of classical mechanics. Deformation analysis of inter-particle contacts does not imply continuity at particle boundaries. As this technique has evolved, it has been used in a wide variety of research applications in mechanics and Geotechnical engineering. However, there are some drawbacks to its use especially in the simulation and interpretation of real granular material behavior. Inadequate understanding of the micro-kinematics of particle rotation and contact rolling have rendered most DEM models ineffective in translating its usefulness to the overall study of the mechanics of granular assemblies.

This study evaluated DEM analysis for the purpose of improving computer simulation models of granular materials in order to enhance the capability of predicting real granular behavior and its usefulness as an alternative to full-scale modeling.

Implicit and explicit numerical integration algorithms are discussed on the basis of a generalized collocation formulation. In relation to DEM, it is shown that the explicit velocity Verlet method improves convergence, stability and accuracy.

Using the concept of rolling friction, closed-form expressions were derived for contact rolling stiffness for both 2-D and 3-D problems. The developed DEM simulation model shows that the effects of rolling friction on the stress-strain behavior, shear strength and the development of shear bands are very significant. The study proves that simulation of granular media is greatly enhanced and the microstructure and micro-mechanisms are better revealed. Validation tests showed good agreement between DEM simulation results and available experimental tests on rod assemblies. Comparisons of heterogeneous deformation fields and the uniform strain fields indicate the need to incorporate a high gradient of strain theory in predicting the constitutive law of granular materials.

Indexing (details)


Subject
Civil engineering;
Materials science
Classification
0543: Civil engineering
0794: Materials science
Identifier / keyword
Applied sciences
Title
Evaluation of discrete element analysis for the mechanics of granular assemblies
Author
Acheampong, Kofi Boakye
Number of pages
226
Publication year
1996
Degree date
1996
School code
0118
Source
DAI-B 57/02, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
Advisor
Chang, Ching S.
University/institution
University of Massachusetts Amherst
University location
United States -- Massachusetts
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
9619365
ProQuest document ID
304259563
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/304259563
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