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vol. 18, nr. 2 (2011)
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Effect of sample width and shape of particles on uniaxial compression of bedding of granular material
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Piotr Parafiniuk, Joanna Wiącek, Marek Molenda, Piotr Frankowski
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Institute of Agrophysics PAS, Doświadczalna 4, 20-290 Lublin, Poland |
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vol. 18 (2011), nr. 2,
pp. 399-408
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abstract:
Uniaxial compression characteristics of granular material were examined as influenced by the shape of particles and the width of cuboidal chamber of the apparatus. The chamber was 0.12 m high and wide, while its width was adjustable in a range from 0 to 0.12 m. Testing was performed on nearly spherical pea seeds and on clearly oblong bean seeds. Numerical simulations of laboratory tests were conducted using the discrete element method (DEM) on assemblies of spherical particles of aspect ratio λ = 1.0 or on assemblies of elongated particles in the form of clusters of three coaxial spheres having aspect ratios λ = 1.3 or λ = 1.6. Asymptotic values of k in laboratory testing were found approximately 0.4 for pea seeds and approximately 0.5 for bean seeds. Similar tendencies were observed earlier in testing of wheat and rapeseeds. The results of numerical simulations were found to be in qualitative agreement with the results of laboratory testing performed. Values of pressure ratio k increased sharply with an increase in sample width up to approximately two particle diameters, and changed only slightly after surpassing this value. In assemblies of elongated particles k stabilised in narrower samples, and pressure ratio increased with an increase in λ . In laboratory testing as well as in numerical simulations strong fluctuations of values of normal load were observed, probably due to rearrangements of contact network.
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keywords:
DEM, discrete element method, granular material, bulk solid, uniaxial compression, numerical simulations
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original in:
Polish
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