Thesis (MEng)--University of Stellenbosch, 2000. / 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.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/51764 |
| Date | 12 1900 |
| Creators | Coetzee, C. J. (Cornelis Jacobus) |
| Contributors | Els, D. N. J., Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 1 v. (various pagings) : ill. |
| Rights | Stellenbosch University |
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