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Badania modelowe zbiornikow na materialy sypkie

100%

Horabik J., Molenda M.

Zeszyty Problemowe Postępów Nauk Rolniczych

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1995

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tom 424

315-320

W pracy porównano rozkłady obciążenia ściany i dna modelowych zbiorników o identycznym kształcie i różnej wielkości napełnionych ziarnem pszenicy. Stwierdzono, że zmiany współczynnika tarcia ziarna o ścianę spowodowane osadzaniem się kutyny na ścianie zbiornika przewyższają znacznie błędy skali.

2

Wplyw sposobu napelniania na rozklad naporu osrodka sypkiego w modelowym zbiorniku

75%

Molenda M., Horabik J.

Problemy Inżynierii Rolniczej

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1996

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tom 04

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nr 1

83-90

W pracy przedstawiono układ eksperymentalny pozwalający na wyznaczenie rozkładu pionowego naporu na płaskie dno modelowego zbiornika oraz średniego naporu normalnego i stycznego na ścianę. Pomiary rozkładu naporu przeprowadzono dla trzech sposobów napełniania zbiornika: centrycznego, obwodowego i rozproszonego. Z praktycznego punktu widzenia najkorzystniejszy rozkład naporu powstaje podczas napełniania obwodowego.

3

Influence of filing method on radial distribution of vertical pressure of rapeseed on bottom of a model bin

75%

Horabik J., Molenda M.

Zeszyty Problemowe Postępów Nauk Rolniczych

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1995

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tom 427

91-97

The packing density and spatial arrangement of individual grains influence the mechanical behaviour of granular material. The method of bin filling influences the spatial arrangement of solid particles and, as a consequence, the pressure distribution. This paper outline an effect of preferred orientation of normal directions in contact points of particles on radial distribution of vertical pressure on the bottom of a model bin.

4

Wplyw wlasciwosci mechanicznych ziarna na rozklad naporu w silosie

63%

Horabik J., Molenda M.

Przegląd Zbożowo-Młynarski

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1998

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tom 42

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nr 04

28-30

5

Wplyw struktury zloza nasion na stan naprezenia

38%

Molenda M.

Acta Agrophysica

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1998

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tom 12

129

The spatial arrangement of individual grains forming a bed of granular solids influences the mechanical behaviour of granular material. Several researchers reported reduction of the coordination number and an increase of the void fraction in the region near the wall of containers holding randomly packed beds of uniform spheres. The method of bin filling influences the pressure distribution on the wall as well as the flow pattern which develops at the onset of discharge. Anisotropic behaviour of grain medium was considered to be the reason for damage to silos built in compliance with current codes of practice. It was found that the filling method influences the magnitude of measured values of the stress ratio. The purpose of this study was to examine the influence of particle properties and bedding structure on transmission of stresses in the layer of seeds, A model bin 0.61 m in diameter and 0.62 m high was constructed. Its bottom was divided into five concentric rings. The apparatus allowed for the determination of vertical load on each of the floor rings, vertical wall load and horizontal load exerted by grain on the bin wall. Four methods of bin filling and two types of wall surface (rough and smooth) were tested. The seeds of five species of plants were used as bulk solids filling the bin. The filing method, and individual seed size and shape of the five test materials significantly influenced the radial distribution of vertical pressure on the silo bottom. From a practical point of view, the advantages of circumferential filling as compared to central filling are: lower pressure ratio, maximum of vertical pressure at the bottom centre and lower tangential stress in vertical direction. The characteristics of vertical pressure as the function of the radius was observed to be smooth for the ratio of bin radius to particle dimension higher than one hundred. The change in moisture content of wheat resulted in the change ofradial distribution of vertical pressure. The wall of the bin was loaded gravitationally and allowed to move down. The characteristics of shear stress as the function of the radius was found to be dependent on the seed size. The major part of shear stress change took place in the boundary layer along the wall, which thickness was less than ten seed equivalent diameters. The proposed method measures vertical normal pressure averaged over the cross sectional area and the horizontal normal pressure averaged over the perimeter. Simultaneously, it measures the coefficient of wall friction, thus the pressure ratio is determined in a manner consistent with the Janssen formula. The pressure ratio value was found affected by material type, filling method and load history. Analysis of radial variation of vertical pressure can be useful in the verification of assumptions concerning the location of regions of fully developed yield conditions inside the Janssen's differential slice which are frequently considered in the theoretical prediction of the stress ratio.

Ograniczanie wyników

2 Zeszyty Problemowe Postępów Nauk Rolniczych

1 Acta Agrophysica

1 Problemy Inżynierii Rolniczej

1 Przegląd Zbożowo-Młynarski

5 Molenda M.

4 Horabik J.

2 1998

1 1996

2 1995

Badania modelowe zbiornikow na materialy sypkie

Wplyw sposobu napelniania na rozklad naporu osrodka sypkiego w modelowym zbiorniku

Influence of filing method on radial distribution of vertical pressure of rapeseed on bottom of a model bin

Wplyw wlasciwosci mechanicznych ziarna na rozklad naporu w silosie

Wplyw struktury zloza nasion na stan naprezenia