Wall friction measurement and compaction characteristics of bentonite powders

Tien, Yong Ming; Wu, Po Lin; Huang, Wei; Kuo, Ming Feng; Chu, Chen An

doi:10.1016/j.powtec.2006.11.023

Cited by 22 publications

(12 citation statements)

References 20 publications

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“…Our test bench has to be designed to enables friction to occur between the I1 sample and the steel tube. Our experimental configuration is similar to the compaction tests one [16], [17], [18].…”

Section: Introductionmentioning

confidence: 99%

A split Hopkinson pressure bar device to carry out confined friction tests under high pressures

Durand

Delvare

Bailly

et al. 2016

International Journal of Impact Engineering

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International audienceNumerical simulations of mechanical loadings on pyrotechnic structures require the determination of the friction coefficient between steel and explosives. Our study focuses on contact pressures of around 100 MPa and sliding velocities of around 10 m/s. Explosives are brittle materials which fracture when submitted to such pressures in uniaxial compression. They have therefore to be confined to avoid any fracture during the tests. A new Hopkinson bar device which simultaneously enables to confine a sample and rub it on steel has therefore been designed. This device is composed of two coaxial transmission bars. It consists in a cylindrical sample confined in a steel tube, the cylindrical sample being inserted between the incident bar and the internal transmission bar, and the confinement tube being leant against the external transmission bar. The high impedance of the external transmission bar keeps the confinement tube quasi-motionless whereas the impedance of the internal transmission bar is calculated to reach the desired pressure and the desired velocity at the tube–sample interface. Tests have been carried out with an inert material mechanically representative of explosives. The friction coefficient and the stresses at the tube–sample interface are deduced from strain measurements on the Hopkinson bars and on the external face of the confinement tube, and from an analytical model

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Section: Introductionmentioning

confidence: 99%

A split Hopkinson pressure bar device to carry out confined friction tests under high pressures

Durand

Delvare

Bailly

et al. 2016

International Journal of Impact Engineering

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“…Their work remains an analysis still used in many powder compaction studies today to consist a force balance on an axial slice of a granular cylinder. It is difficult to eliminate die wall friction force of conventional compaction and there are many research studies about it [9][10][11][12][13]. Let us consider the powder disc of deformation of the cylinder shape with diameter D=2r in Fig.…”

Section: A Case Of the Conventional Methodsmentioning

confidence: 99%

The comparison of model compaction method to make uniformly dense ceramic bodies

Хасанов

Edgar

Sokolov

et al. 2012

2012 7th International Forum on Strategic Technology (IFOST)

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The "collector" method of uniaxial dry compacting homogeneously dense powdered bodies of complex shape without macroscopic defects has been developed. It was based on the selfalignment of uniform density regions within a green compact by design of special mold to reduce die-wall friction effects. An equation was proposed that determined the density differential throughout the height of a green compact, which depended on geometrical parameters, and required the controlled movement of die parts. The technique of pressing with the collector method has been developed and patented by TPU. Based on the principles of the collector method a compaction mold of spiral type was modeled for compaction of cylindrical compacts with two alternating, oppositely-moving parts of the passive shaping surface with sliders, twisted at an angle of 36 degrees. The process of powder compaction was simulated by finite element method. The simulation results of the deformation process in the compacts showed that the density of each layer distributed irregularly with the curvature of isosurfaces in the direction of movement of the punch. The results of comparative simulation showed that the statistical dispersion of local values of the deformation of the green compacts made by collector method with the mold of spiral type is reduced to 48% when compared with conventional static compaction and reduced to 5% when compared with collector compaction using the mold of non-spiral type. This method decreases the density gradients. It can be applied to manufacture ceramic articles from nanopowders like impellers and plates with longitudinal holes.

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“…The friction index (f) gives the ratio of the shear stress to axial stress and is an indication of the friction effect [21,22]. Thus, it is a significant parameter for powder compaction.…”

Section: Friction Indexmentioning

confidence: 99%

X-ray tomography analysis of aluminum alloy powder compaction

Yang

Zhang

2015

Rare Met.

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Aluminum alloy green compacts obtained by single-action compaction in lubricated and unlubricated dies were investigated by X-ray tomography. For the purpose of obtaining the relationship between the density of green compact and the gray value of reconstructed images, linear fitting was performed. The results show that these data have excellent linear relationship. Then, a new method for analysis of compaction process was presented in this paper. Detailed quantitative analysis of the density and compressive pressure distribution in green compacts was performed. The compressive pressure transmitted ratio and friction index were also discussed. It is found that the lubricated die wall has better effects on the density homogeneity at lower applied compressive pressure. During compaction process, the densification of powder particles in the die mainly occurs in the lower part of the green compact and the factor which mainly influences the friction between die wall and green compact is the applied compressive pressure.

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Wall friction measurement and compaction characteristics of bentonite powders

Cited by 22 publications

References 20 publications

A split Hopkinson pressure bar device to carry out confined friction tests under high pressures

A split Hopkinson pressure bar device to carry out confined friction tests under high pressures

The comparison of model compaction method to make uniformly dense ceramic bodies

X-ray tomography analysis of aluminum alloy powder compaction

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