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Micromechanical modeling of the inte...

Subramanian, Sankara Jayaraman.

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Micromechanical modeling of the interaction of diffusion mechanisms and surface energy with nonlinear material deformation: Applications to powder densification and void growth.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Micromechanical modeling of the interaction of diffusion mechanisms and surface energy with nonlinear material deformation: Applications to powder densification and void growth./
Author:	Subramanian, Sankara Jayaraman.
Description:	211 p.
Notes:	Adviser: Petros Sofronis.
Contained By:	Dissertation Abstracts International62-08B.
Subject:	Applied Mechanics. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3023208
ISBN:	0493349685

Micromechanical modeling of the interaction of diffusion mechanisms and surface energy with nonlinear material deformation: Applications to powder densification and void growth.
Subramanian, Sankara Jayaraman.

Micromechanical modeling of the interaction of diffusion mechanisms and surface energy with nonlinear material deformation: Applications to powder densification and void growth. - 211 p.

Adviser: Petros Sofronis.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2001.

Diffusive processes coupled to nonlinear material behavior assume importance in such important technological problems as consolidation of powders, diffusive cavitation at grain-boundary interfaces, and void growth and coalescence in solids. The first three chapters of this thesis are devoted to the study of powder densification using a small-strain finite-element scheme. In the first chapter, the coupled action of stress-driven diffusion and curvature-driven diffusion over the interparticle contact areas and the pore surfaces respectively, and elasticity and power-law creep processes in the bulk of the particles is studied. Numerical results indicate that the interaction of the deformation mechanisms is very important in determining the overall densification rates of the powder aggregate, and that models that focus on a single, dominant densification mechanism underestimate the densification rate. In the second chapter, the macroscopic strain rate of a particle aggregate is obtained from an analytically-constructed and numerically-obtained potential function in terms of the applied loads, the relative density of the compact, and material parameters. The predictions of this potential agree quantitatively with experimentally obtained densification data for copper wires. The interparticle diffusion process is modified in the third chapter to account for the situation when part of the externally delivered power is expended in driving the interface reaction (addition to or removal of atoms from the interparticle boundaries). Numerical computations reproduce experimentally observed decrease in overall densification rates with increasing interface reaction strength. In order to study densification to a larger range of relative density, the densification problem is recast in finite-strain form in the fourth chapter, and it is observed that the small-strain model underestimates the relative density increase for a given amount of time.

ISBN: 0493349685Subjects--Topical Terms:

1018410
Applied Mechanics.

Micromechanical modeling of the interaction of diffusion mechanisms and surface energy with nonlinear material deformation: Applications to powder densification and void growth.
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005 20110510
008 110510s2001 eng d
020 $a 0493349685
035 $a (UnM)AAI3023208
035 $a AAI3023208
040 $a UnM $c UnM
100 1 $a Subramanian, Sankara Jayaraman. $3 1259668
245 1 0 $a Micromechanical modeling of the interaction of diffusion mechanisms and surface energy with nonlinear material deformation: Applications to powder densification and void growth.
300 $a 211 p.
500 $a Adviser: Petros Sofronis.
500 $a Source: Dissertation Abstracts International, Volume: 62-08, Section: B, page: 3681.
502 $a Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2001.
520 $a Diffusive processes coupled to nonlinear material behavior assume importance in such important technological problems as consolidation of powders, diffusive cavitation at grain-boundary interfaces, and void growth and coalescence in solids. The first three chapters of this thesis are devoted to the study of powder densification using a small-strain finite-element scheme. In the first chapter, the coupled action of stress-driven diffusion and curvature-driven diffusion over the interparticle contact areas and the pore surfaces respectively, and elasticity and power-law creep processes in the bulk of the particles is studied. Numerical results indicate that the interaction of the deformation mechanisms is very important in determining the overall densification rates of the powder aggregate, and that models that focus on a single, dominant densification mechanism underestimate the densification rate. In the second chapter, the macroscopic strain rate of a particle aggregate is obtained from an analytically-constructed and numerically-obtained potential function in terms of the applied loads, the relative density of the compact, and material parameters. The predictions of this potential agree quantitatively with experimentally obtained densification data for copper wires. The interparticle diffusion process is modified in the third chapter to account for the situation when part of the externally delivered power is expended in driving the interface reaction (addition to or removal of atoms from the interparticle boundaries). Numerical computations reproduce experimentally observed decrease in overall densification rates with increasing interface reaction strength. In order to study densification to a larger range of relative density, the densification problem is recast in finite-strain form in the fourth chapter, and it is observed that the small-strain model underestimates the relative density increase for a given amount of time.
520 $a Void growth in nonlinearly creeping solids under plane-strain conditions is studied in the fifth chapter. Numerical results reveal a rich variety of solutions; in general, void shape is controlled by the strength of the diffusion process relative to the bulk creep process, whereas void size depends critically on the surface energy of the void in relation to the void size and applied load.
590 $a School code: 0090.
650 4 $a Applied Mechanics. $3 1018410
650 4 $a Engineering, Materials Science. $3 1017759
650 4 $a Engineering, Mechanical. $3 783786
690 $a 0346
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690 $a 0794
710 2 0 $a University of Illinois at Urbana-Champaign. $3 626646
773 0 $t Dissertation Abstracts International $g 62-08B.
790 $a 0090
790 1 0 $a Sofronis, Petros, $e advisor
791 $a Ph.D.
792 $a 2001
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3023208