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  • Author: Józef Horabik x
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Józef Horabik and Marek Molenda

Abstract

The influence of the filling method, the seed size and the aspect ratio on the radial distribution of the vertical pressure on the floor of a shallow model silo and radial distribution of tangent stress within the material was investigated. Three filling methods were applied: central, circumferential and distributed. Seeds of five varieties were used: horse bean, field pea, wheat, vetch, and rapeseed. Vertical pressure on the floor of a shallow bin was found to be influenced by the filling method and the seed size and aspect ratio. A significant dip of vertical pressure in the middle radial location was observed in all tests, except two: central and circumferential filling of rapeseed. Wall friction was mobilized in the highest degree in the case of the central filling, while the lowest was mobilization of friction in the case of the circumferential filling.

Open access

Mateusz Stasiak, Marek Molenda, Józef Horabik, Peter Mueller and Ireneusz Opaliński

Abstract

Laboratory testing was conducted to deliver a set of characteristics of structure and mechanical properties of pure starch and starch with an addition of a lubricant - magnesium stearate. Considerable influence of moisture content of potato starch was found in the case of density, parameters of internal friction, coefficients of wall friction and flowability. Elasticity was found to be strongly influenced by water content of the material. Addition of magnesium stearate affected density and parameters of flowability, internal friction and elasticity. Bulk density increased from 604 to 774 kg m-3 with decrease in moisture content of potato starch from 17 to for 6%. Addition of magnesium stearate resulted in approximately 10% decrease in bulk density. Angle of internal friction obtained for 10 kPa of consolidation stress decreased from 33 to 24º with increase in moisture content, and to approximately 22º with addition of the lubricant. With an increase of moisture content from 6 to 18% and with addition of the lubricant, the modulus of elasticity during loading decreased from approximately 1.0 to 0.1 MPa. Modulus of elasticity during unloading was found in the range from 19 to 42 MPa and increased with increase of moisture content and amount of lubricant.