Stress and deformation of wheat in direct shear test
M. Molenda 1,   J. Horabik 1,   J. Ross 2
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Institute of Agrophysics, Polish Academy of Sciences, Doświadczalna 4, P.O.Box 121,20-290 Lublin 27, Poland
Biosystems and Agricultural Engineering Department, University of Kentucky, 128 Agricultural Engineering Bldg.Lexington, Kentucky 40546-0276, U.S.A.
Acceptance date: 1998-01-19
Int. Agrophys. 1998, 12(2): 115–118
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.