Persistent Link:
http://hdl.handle.net/10150/289522
Title:
Mechanics of particulate media: A lattice-type approach
Author:
Ramakrishnan, S, 1964-
Issue Date:
1997
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
This research is aimed at understanding the mechanical behavior of particulate/granular media using the power of lattice based techniques. In the lattice type model, a particulate assembly is simulated as a lattice/truss network. Nodes are relocated at contacts between a particle and its neighbors/boundaries and are linked by bars to each other. Each particle is replaced by a lattice within its microstructure and particles interact through load transfer at nodes. Constraints are prescribed at the nodes of the lattice to simulate active, deactivated, and reactivated contacts. An assembly of particles is thus transformed into a lattice/truss and is analyzed using standard methods of structural mechanics under appropriate boundary conditions. When a particulate assembly develops into a mechanism (deformation with zero incremental load), further deformation is simulated through a framework that describes the kinematics of the particles (sliding, rolling, and rotation of particles). This framework is formed by introducing nodes at the particle centroids and linking them with bars. Bars linking particles with a non-sliding contact are assigned large stiffnesses relative to bars linking particles with a sliding contact. Numerical tests are conducted on two dimensional assemblies of disks, arranged as very loose and very dense packings under simple shear loading conditions. The results concord with the results of numerical tests conducted using the discrete element method at low strain levels and with photoelastic experiments up to large shear strain levels. The model is applied to study the effects of initial imperfections caused by particles with low elastic modulus. A dense assembly of disks, with 25% of the particles having an elastic modulus 1/100th of the elastic modulus of the remaining particles, resulted in a decrease of 67% for the shear modulus of the whole assembly. The lattice type model is conceptually simple but has some powerful features that can account for initial particle imperfections, anisotropy, and particle crushing.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Applied Mechanics.; Engineering, Civil.; Engineering, Mechanical.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Civil Engineering and Engineering Mechanics
Degree Grantor:
University of Arizona
Advisor:
Budhu, Muniram; Frantziskonis, George

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleMechanics of particulate media: A lattice-type approachen_US
dc.creatorRamakrishnan, S, 1964-en_US
dc.contributor.authorRamakrishnan, S, 1964-en_US
dc.date.issued1997en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThis research is aimed at understanding the mechanical behavior of particulate/granular media using the power of lattice based techniques. In the lattice type model, a particulate assembly is simulated as a lattice/truss network. Nodes are relocated at contacts between a particle and its neighbors/boundaries and are linked by bars to each other. Each particle is replaced by a lattice within its microstructure and particles interact through load transfer at nodes. Constraints are prescribed at the nodes of the lattice to simulate active, deactivated, and reactivated contacts. An assembly of particles is thus transformed into a lattice/truss and is analyzed using standard methods of structural mechanics under appropriate boundary conditions. When a particulate assembly develops into a mechanism (deformation with zero incremental load), further deformation is simulated through a framework that describes the kinematics of the particles (sliding, rolling, and rotation of particles). This framework is formed by introducing nodes at the particle centroids and linking them with bars. Bars linking particles with a non-sliding contact are assigned large stiffnesses relative to bars linking particles with a sliding contact. Numerical tests are conducted on two dimensional assemblies of disks, arranged as very loose and very dense packings under simple shear loading conditions. The results concord with the results of numerical tests conducted using the discrete element method at low strain levels and with photoelastic experiments up to large shear strain levels. The model is applied to study the effects of initial imperfections caused by particles with low elastic modulus. A dense assembly of disks, with 25% of the particles having an elastic modulus 1/100th of the elastic modulus of the remaining particles, resulted in a decrease of 67% for the shear modulus of the whole assembly. The lattice type model is conceptually simple but has some powerful features that can account for initial particle imperfections, anisotropy, and particle crushing.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectApplied Mechanics.en_US
dc.subjectEngineering, Civil.en_US
dc.subjectEngineering, Mechanical.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineCivil Engineering and Engineering Mechanicsen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorBudhu, Muniramen_US
dc.contributor.advisorFrantziskonis, Georgeen_US
dc.identifier.proquest9738949en_US
dc.identifier.bibrecord.b37467724en_US
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