Compaction of an array of spherical particles

Ogbonna, Nkem; Fleck, N.A.

doi:10.1016/0956-7151(94)00286-q

Cited by 37 publications

(15 citation statements)

References 9 publications

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“…Here we present a detailed analysis of this problem including convergence studies, and evaluation of the accuracy of the proposed methodology. To date, a majority of the published research regarding the computational (analytical and simulation) compaction of particulate material has focused on the probing of strength of compacted bodies (Fleck, 1995;Ogbonna and Fleck, 1995;Redanz and Fleck, 2001;Heyliger and McMeeking, 2001;Martin et al, 2003;Xin et al, 2003). The work presented here aims to understand the development of the yield surface during monotonic loading to a given density.…”

Section: Introductionmentioning

confidence: 98%

Simulation of multi-axial compaction of granular media from loose to high relative densities

Procopio

Zavaliangos

2005

Journal of the Mechanics and Physics of Solids

141

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Section: Introductionmentioning

confidence: 98%

Simulation of multi-axial compaction of granular media from loose to high relative densities

Procopio

Zavaliangos

2005

Journal of the Mechanics and Physics of Solids

141

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“…The compaction response of the cubic array of spherical particles is considered in terms of a representative unit cell of the aggregate. Following Ogbana and Fleck [3], the unit cell is taken to be a single spherical particle circumscribed by a circular cylinder the height of which is twice the radius of the undeformed sphere R o , Fig.1(b). In fact, during compaction, the top and bottom planes of the unit cell surrounding a representative particle approach each other, and the cylindrical boundary of the cell shrinks in diameter that can be interpreted as the contribution from the four particle contacts surrounding the mid-section of a typical particle.…”

Section: Powder Structure and Unit Cellmentioning

confidence: 99%

“…More recently Sridhar et al [1] have studied the biaxial compaction of a square array of uniform circular cylinders using slip-line field, upper bound (kinematic approach) and finite element methods to examine, under hydrostatic and closed die compaction, the evolution of contact size, contact pressure and macroscopic yield surfaces for stage I and II of compaction. Ogbonna and Fleck [3] have studied the threedimensional compaction response of an array of identical spherical particles in terms of a representative unit cell of the aggregate submitted to axisymmetrical loading conditions. They used only numerical simulations investigation to examine the evolution of contact size, contact pressure and macroscopic yield surfaces for stage I and II of compaction.…”

Section: Introductionmentioning

confidence: 99%

“…In this study the focus of the analysis in on powder compaction and the kinematic approach of the yield design theory [2] is used as the technique of solution for the construction of an estimate of the macroscopic yield surfaces of the powder compacts. The obtained results are compared to numerical ones issued from the compaction response of a representative unit cell as adopted by Ogbonna and Fleck [3].…”

Section: Introductionmentioning

confidence: 99%

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An estimate of the macroscopic yield surfaces of powder compacts using the kinematic approach of the yield design theory

Benabbes

Dormieux²,

Siad

2008

Int J Mater Form

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The 3D compaction of a square array of spherical particles of uniform size is studied using the kinematic approach of the yield design theory. The densification is assumed to occur by plastic deformation at the mutual zone contacts between grains where the dissipation is localized. The compaction response of the array of spherical particles is considered in term of representative unit cell of the aggregate submitted to axisymmetrical loading conditions. Approximate macroscopic yield surfaces resulting from hydrostatic and closed die compaction are constructed at various stages of densifications. The size and shape of the yield surfaces depend upon the loading history as well as the relative density of the compact. Finite element simulations have also been performed in order to validate to some extent the results provided by the kinematic approach of the yield design theory and to examine the evolution of macroscopic yield surface with the degree of compaction.

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“…La figura 5 representa el modelo analizado por estos autores y un detalle de los esfuerzos en el contacto entre dos partículas esféricas. Ogbonna y Fleck [28] demostraron que la cadencia de un agregado de partículas depende no solo de su densidad sino también del camino de carga apliFigura 2. Modelo bidimensional [17] .…”

Section: Modelización Micromecánicaunclassified

Modelling of the plasticity in cold compaction of metal powders

Riera¹,

Prado²

2006

Rev. metal.

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Aparte de sus numerosas ventajas, la pulvimetalurgia presenta también algunas restricciones. Algunas de ellas dependen del propio proceso y afectan principalmente al diseño de la pieza. Los requerimientos geométricos y los que conciernen a la tenacidad limitan las posibilidades de esta tecnología. Otro tipo de limitaciones, también bien establecidas, están asociadas a la etapa de compactación: la fricción entre las partículas y las herramientas induce en el compacto una distribución no uniforme de densidad. El estado de tensiones heterogéneo que se desarrolla, especialmente durante la eyección del molde, produce, frecuentemente, grietas en la preforma e incluso la fractura del molde.Todos estos problemas se han resuelto tradicionalmente mediante métodos de trial and error. Sin embargo, el desarrollo reciente de nuevas y eficientes herramientas de cálculo puede contribuir a reducir el coste del diseño de los procesos de fabricación y contribuir a mejorar la calidad del producto final. A este respecto, el principal objetivo de la simulación numérica es determinar la forma óptima de producir piezas sin de- La industria pulvimetalúrgica está interesada en extender las aplicaciones y mejorar la calidad de sus productos. Para ello, necesita un conocimiento detallado de sus procesos que permita su control. La representación del comportamiento mecánico de estos materiales se ha realizado utilizando diversos tipos de modelos; en la actualidad, la mayoría de los grupos de trabajo considera a los polvos metálicos como materiales granulares. Los modelos de plasticidad definidos para los materiales geológicos se están aplicando a los agregados metáli-cos. Sin embargo, ninguno de los modelos conocidos puede representar adecuadamente su comportamiento mecánico, especialmente en estados de fallo. Palabras ClavePlasticidad. Materiales granulares. Compactación de polvos metálicos. Modelización. Modelling of the plasticity in cold compaction of metal powders AbstractPowder metallurgical industry is very interested in spreading its applications and improve the quality of the PM products. Therefore, a detailed knowledge of their processes, in order to control them, is necessary. Many different types of models have been used to represent the mechanical behaviour of these materials; however, nowadays, most of the groups working in this field admit that metallic powders and green compacts have to be considered as granular materials. Plasticity models specially defined for geological materials are being applied on metallic aggregates. Nevertheless, none of the known ones can represent adequately their mechanical behaviour, specially in states of failure. KeywordsPlasticity. Granular materials. Compaction of metal powders. Modelling.

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Compaction of an array of spherical particles

Cited by 37 publications

References 9 publications

Simulation of multi-axial compaction of granular media from loose to high relative densities

Simulation of multi-axial compaction of granular media from loose to high relative densities

An estimate of the macroscopic yield surfaces of powder compacts using the kinematic approach of the yield design theory

Modelling of the plasticity in cold compaction of metal powders

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