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International Agrophysics
publisher:Institute of Agrophysics
Polish Academy of Sciences
Lublin, Poland
ISSN: 0236-8722


vol. 12, nr. 2 (1998)

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Stress and deformation of wheat in direct shear test
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Molenda M.1, Horabik J.1, Ross J.2
1 Institute of Agrophysics, Polish Academy of Sciences, Doświadczalna 4, P.O.Box 121,20-290 Lublin 27, Poland
2 Biosystems and Agricultural Engineering Department, University of Kentucky, 128 Agricultural Engineering Bldg.Lexington, Kentucky 40546-0276, U.S.A.

vol. 12 (1998), nr. 2, pp. 115-118
abstract A method was developed and a device constructed to measure the force of internal friction of granular materials. The angle of internal friction of wheat grain was determined for two displacement speeds (0.5 and 5 mm/min) in the normal pressure range from 2.8 to 48 kPa. The angle of internal friction was found to decrease with an increase in normal pressure. Slip-stick behaviour was observed when the shearing speed equaled 0.5 mm/min. With an increase in displacement the deformation is localised in a shear zone. The thickness of the shear zone stabilised soon after the shear stress reached maximum value.
keywords wheat, friction, direct shear test