Numerical modelling of particle contact deformation

Dellis, C.; Bouvard, D.; Stutz, P.

doi:10.1016/b978-0-444-89959-0.50011-6

Cited by 7 publications

(4 citation statements)

References 7 publications

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“…As shown in Fig. 3, the contact area is subtended by an angle, c, which is less than 0.1 to minimize the error from physical deformation (Dellis et al, 1994). For simplicity, this is referred to as the twosphere system.…”

Section: Configurations and Formulationmentioning

confidence: 99%

Transient effect on the constriction resistance between spheres

Siu

Lee

2000

Computational Mechanics

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Systems of contacting spheres are common in engineering applications where the heat transfer analysis can be quite cumbersome due to the transient behavior and the complex geometrical arrangement. As a result, most of the previous works, in this area, have adopted the porous media approach. However, this approach requires the length scale of the representative cell to be roughly three orders of magnitude larger than the size of the spheres. Constriction resistance relations could be useful in accurately computing the temperature distribution within systems of contacting spheres, however many of the requisite relations are not available. Thus, the objective of this study is to develop these relations. In this study, the transient, three-dimensional conduction equation was solved using a ®nite volume scheme and a non-uniform grid. From the resulting temperature distributions, the steady-state and transient constriction resistance of one-sphere and twosphere systems were computed and correlated. The results also showed, for the ®rst time, the critical parameters below which the transient variations must be considered.List of symbols a constriction alleviation factor, R ss kr c A area, m 2 C speci®c heat, J/kg-K Fo Fourier number, asar 2 c k thermal conductivity, W/m-K M total number of spheres in system q heat¯ux, W/m 2 Q total heat transfer, W r,h radial and angular variable in spherical coordinate, m, rad R thermal constriction resistance, K/W T temperature, K U internal energy, òqCT dV V volume, m 3Greek letters a thermal diffusivity, m 2 /s c ratio of contact radius to sphere radius, r c /r s q density, kg/m 3 s time, s Subscripts b bulk temperature c contact i initial value s sphere, or length scale with r s ss steady state value IntroductionHeat transfer within systems with contacts are common in engineering applications. These include insulated cables (cf. Liu et al., 1998), composite materials (cf. Lewinski and Kucharski, 1992) and packed-sphere systems (cf. Chan and Tien, 1973). For these systems, the heat transfer analysis can be quite complicated due to the transient behavior and the complex geometrical contact arrangement. For the packed-sphere system, the boundary condition of each sphere as well as the number of conduction path are affected by the number of contacting spheres, the orientation between these contacts, and the size of the contact areas. Furthermore, the air gap between the spheres also affects the heat transfer by introducing convective and radiative effects.Due to these complexities, most of the previous works in the packed-sphere system have adopted the porous media approach. This approach uses lumped-parameter models to either measure or compute the effective thermal conductivity of a representative cell (cf. Hsu et al., 1994). However, this requires the length-scale of the representative cell to be roughly three orders of magnitude larger than the size of the spheres (Kaviany, 1995). Consequently, the temperature solution obtained from the porous media approach may not be suitable for...

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Section: Configurations and Formulationmentioning

confidence: 99%

Transient effect on the constriction resistance between spheres

Siu

Lee

2000

Computational Mechanics

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“…The problem therefore involves calculating the area ratio (A E /A N ), which in turn entails determining the contact area between particles. Contacts between deformable bodies have been examined with analytical methods by several authors; 5-7 more recently, they have also been the subject of numerical studies 8,9 based on finite element methods. In this work, for biaxial compression, the area ratio for an ideal powder particles aggregate consisting of spheres with a simple cubic packing, has been calculated.…”

Section: Modelling Work Assumptionsmentioning

confidence: 99%

Effective stress during biaxial compression of powder aggregates

Montes¹,

Cuevas²,

Cintas³

et al. 2005

Materials Science and Technology

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An equation to calculate the effective stress acting on interparticle contacts during the biaxial compression of a powder aggregate is proposed. This equation is obtained by a new method in which the study of the stress-strain relationship is not necessary. This new method does not require the use of sophisticated numerical computation software. The proposed expression satisfies upper and lower boundary conditions, and its range of application is greater than that of other equations, which are often limited to very small deformations. In this work, initially, simple cubic packing of spheres is studied, and then results are extrapolated to real powder systems using a normalised porosity. The proposed equation can be useful in compaction and extrusion processes.

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“…Engineering components are being manufactured to near net shape by HIPping to consolidate powder using complex internal mould within the capsule to define the shape of the final component, it is becoming an accepted technology to produce complex-shaped and fully dense component [1][2][3][4]. The potential economic advantages of near-net-shape HIPping have been investigated [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Near Net Shape Forming Process of a Titanium Alloy Component Using Hot Isostatic Pressing with Graphite Mould

Peng

Huang

et al. 2014

AMM

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Ti6Al4V component has been formed by hot isostatic pressing (HIPping) using internal graphite mould with Ni isolation layer. The shape of the graphite had no deformation after HIPping. The Ni isolation layer with a thickness of approximately 5μm on graphite before HIPping was diffused into the dense Ti6Al4V component surface and formed a uniform, compact and crack free layer with a thickness of approximately 100μm after HIPping. The Ni diffusion layer is not damaged after removing the graphite mould by unpolluted sandblasting. The interface topography and the elements diffusion have been assessed and it is found that the non-machined surface of Ti6Al4V component was improved by using graphite mould than those used mild steel. The roughness of non-machined surface after removing the graphite mould by sandblasting is Ra=1.6μm, and the roughness of non-machined surface after removing the mild steel by acid pickling is Ra=10.8μm. It is concluded that graphite mould could be used for the HIPping process to produce complex-shaped components.

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Numerical modelling of particle contact deformation

Cited by 7 publications

References 7 publications

Transient effect on the constriction resistance between spheres

Transient effect on the constriction resistance between spheres

Effective stress during biaxial compression of powder aggregates

Near Net Shape Forming Process of a Titanium Alloy Component Using Hot Isostatic Pressing with Graphite Mould

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