Some behaviors of shallow vibrated beds across a wide range in particle size and their implications for powder classification

Thomas, B.; Mason, M.O.; Squires, Arthur M.

doi:10.1016/s0032-5910(00)00237-0

Cited by 37 publications

(11 citation statements)

References 30 publications

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“…More recently, it has been shown how the convective velocity field depends on the adimensional acceleration and other parameters, such as frequency and the air pressure [18,19], and new theoretical models have been developed [20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Time resolved particle dynamics in granular convection

Pastor¹,

Maza²,

Zuriguel³

et al. 2007

Physica D: Nonlinear Phenomena

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We present an experimental study of the movement of individual particles in a layer of vertically shaken granular material. High-speed imaging allows us to investigate the motion of beads within one vibration period. This motion consists mainly of vertical jumps, and a global ordered drift. The analysis of the system movement as a whole reveals that the observed bifurcation in the flight time is not adequately described by the Inelastic Bouncing Ball Model. Near the bifurcation point, friction plays an important role, and the branches of the bifurcation do not diverge as the control parameter is increased. By fitting the grains trajectories near the wall it is possible to quantify the effective acceleration acting on them. A comparison of the mass centre flying time and the flying time determined for the grains near the wall exposes the underlying mechanism that causes the downward flow.

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Section: Introductionmentioning

confidence: 99%

Time resolved particle dynamics in granular convection

Pastor¹,

Maza²,

Zuriguel³

et al. 2007

Physica D: Nonlinear Phenomena

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“…The standard vibration experiment consists of a powder in a container mounted on a rigid base, which is subjected to mechanical vibrations. For deep beds this simple experiment exhibits a rich phenomenology depending on the intensity and direction of vibration, from compaction1 at small vertical vibration intensities, to fluidization at high‐vibration intensities,2 passing through convective instability as first discovered by Faraday 3…”

Section: Introductionmentioning

confidence: 97%

Effect of vibration on flow properties of fine glass beads

2008

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in Wiley InterScience (www.interscience.wiley.com).An estimation of cohesion C and angle of internal friction u of fine glass beads, which have been previously subjected to small intensity vertical vibrations of controlled frequency and amplitude for a fixed period of time, is presented. In the range of vibration intensities tested previbration causes powder compaction. Experimental measurements to obtain C and u have been performed by means of a centrifuge powder tester in which the previbrated powder bed is rotated around its vertical axis. At a critical rotation velocity the shear stress induced by rotation is large enough to drive material avalanches. From a theoretical analysis of these avalanches, based on the Coulomb's method of wedges, C and u are derived. We have found a significant increase of cohesion, and a slight decrease of the angle of internal friction as the effective consolidation stress due to previbration is increased. The estimated interparticle cohesion force f t from the experimental measurements, and using a Rumpf's averaging equation, is in agreement with the calculated interparticle attractive force due to van der Waals and capillary interaction for the unconsolidated beds. Moreover f t increases as the effective consolidation stress is increased in agreement with estimations from theoretical models based on contact plasticity. This result suggests that, at the microscopic level of asperities, compaction due to previbration is able to induce plastic deformation of the contacts.

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“…This creates a different environment to a simply mechanically vibrated powder bed, with the absence of fluidizing air flow. While studies have been made into the behavior of powder beds under mechanical vibration [13,14], none have observed or characterized auto-granulation behaviour of the powder.…”

Section: Introductionmentioning

confidence: 99%

Effect of mechanical vibration on the size and microstructure of titania granules produced by auto-granulation

Hare

Ghadiri

et al. 2015

Powder Technology

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ReuseUnless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request.Effect of mechanical vibration on the size and microstructure of titania granules produced by auto-granulation Nicholas Ku, Colin Hare, Mojtaba Ghadiri, Martin Murtagh, Richard A. Haber Abstract Auto-granulation is the growth of particle clusters within a dry, fine powder bed due to the bulk powder cohesion. This clustering occurs without the addition of any binder to the system due to simple agitation of a powder, such as during storage or handling. For this reason, it is important in powder processing to be able to characterize this behavior. In this study, a submicron titania powder is mechanically vibrated under controlled conditions to induce clustering and promote auto-granulation. The amplitude and frequency of the vibration is varied to view the effect on the equilibrium granule size. A statistical model of the effect is also developed to determine that the granule size increases linearly with vibrational energy. Furthermore, imaging of cross-sections of the granules is conducted to provide insight into to the internal microstructure and measure the packing fraction of the constituent particles. It is found that under all vibrational conditions investigated the particles exhibit a core-rim microstructure.

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Some behaviors of shallow vibrated beds across a wide range in particle size and their implications for powder classification

Cited by 37 publications

References 30 publications

Time resolved particle dynamics in granular convection

Time resolved particle dynamics in granular convection

Effect of vibration on flow properties of fine glass beads

Effect of mechanical vibration on the size and microstructure of titania granules produced by auto-granulation

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