Forced granular flow

Coetzee, C. J. (Cornelis Jacobus) (2000-12)

Thesis (MEng)--University of Stellenbosch, 2000.

Thesis

ENGLISH ABSTRACT: The main goal of the thesis is to validate the ability of discrete element methods (DEM) to predict forced granular flow. Granular flow occurs in a broad spectrum of industrial applications. The thesis focuses on earthmoving processes typical of the mining and agricultural industries. Existing soil mechanics soil-tool models are also investigated and general flow behaviour in and around blades and buckets are established. Soil mechanics theories are used to predict the draft forces on a flat blade moving through granular material. Com and wheat grains are used as material. The rupture (slip) lines in front of the blade are predicted by soil mechanics and compared to experimental results. A two-dimensional test bench is used to visualise the flow of the granular material. Forces and moments that act on the tools are measured. DEM can be used to model industrial granular flow with large displacements. Two types of earthmoving equipment are simulated. The first is a flat blade and the second is a bucket. The forces on these tools are determined using DEM and compared to experimental results. The ability of DEM to predict material compressibility, the flow of material in and around the tools, the rupture lines and the bucket fill rate are investigated. A particle relative displacement method is used to determine the rupture lines.

AFRIKAANSE OPSOMMING: Die hoofdoel van die tesis is om die vermoë van diskrete-element-metodes (DEM) om geforseerde partikelvloei te voorspel, te ondersoek. Partikelvloei word aangetref in 'n breë spektrum van industriële toepassings. Die tesis fokus op grondverskuiwing soos aangetref in myn- en landbouprosesse. Bestaande grondmeganika-modelle word ook ondersoek, asook die algemene gedrag van partikelvloei in en rondom lemme en bakke. Die grondmeganika-modelle word hoofsaaklik gebruik om die kragte op lemme te voorspel. Glip (skuif)-vlakke word ondersoek en vergelyk met eksperimentele resultate. 'n Twee-dimensionele toetsbank word gebruik om die vloei waar te neem. Die kragte en momente op die toerusting word ook gemeet. Mielie- en koringpitte word as materiaal gebruik. DEM kan gebruik word om industriële partikelvloei met groot verplasings te modelleer. Twee tipes toerusting word gesimuleer. Die eerste is 'n plat lem en die tweede 'n bak. Die kragte en momente op dié toerusting word bepaal m.b.V. DEM en dan vergelyk met die eksperimentele resultate. Die vermoë van DEM om materiaalsamedrukking, vloeipatrone, glipvlakke en bakvul-tempo's te voorspel word ondersoek. 'n Partikelrelatiewe- verplasings-metode word gebruik om die glipvlakke te voorspel.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/51764
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