Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2007. / Vibrating a tillage tool is an effective way of reducing the draft force required
to pull it through the soil. The degree of draft force reduction is dependent on the
combination of operating parameters and soil conditions. It is thus necessary to
optimize the vibratory implement for different conditions.
Numerical modelling is more flexible than experimental testing and analytical
models, and less costly than experimental testing. The Discrete Element Method
(DEM) was specifically developed for granular materials such as soils and can be
used to model a vibrating tillage tool for its design and optimization. The goal
was thus to evaluate the ability of DEM to model a vibratory subsoiler and to
investigate the cause of the draft force reduction.
The DEM model was evaluated against data obtained from field testing done
with a full scale single tine vibratory subsoiler. Soil testing was also done for
material characterization and for the calibration of DEM material properties.
The subsoiler was simulated using a commercial code, PFC3D. The effect on
the simulation results of particle diameter, different bonding models and damping
models was investigated. The final simulations were evaluated against the experimental
results in terms of the draft force and material behaviour. The cause of
the draft force reduction due to vibration was also investigated with the aid of the
DEM model.
From the results it was concluded that DEM is able to model the vibratory
subsoiler for its design and optimization. The DEM model also provided valuable
insight into the cause of the draft force reduction such as the increased peak stresses
due to vibration and the increase in particle kinetic energy.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/2865 |
| Date | 12 1900 |
| Creators | Van der Linde, Jaco |
| Contributors | Els, D. N. J., University of Stellenbosch. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 10538178 bytes, application/pdf |
| Rights | University of Stellenbosch |
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