Creation, optimization and verification of a three dimensional numerical model to simulate a dragline bucket during the digging cycle using modern DEM software
Date
2007-12
Authors
Dymond, Graeme Francois Dryden
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : University of Stellenbosch
Abstract
Dragline bucket designers are required to evaluate new bucket designs by building and testing scale buckets. Concerns about the reliability and accuracy
of scale testing have been raised in recent years, but there was no alternative.
However, recent advances in computing power and granular flow modeling are
changing this and, we are entering an era where it is possible to numerically
simulate dragline bucket filling. However, verification of the numerical simulation
is necessary before useable data can be obtained.
This thesis explains the algorithm used by modern discrete element codes
to simulate granular materials. The process used to create the numerical model
and calibrate the material will be discussed. An experimental test bench was
also built to record experimental data for the verification the numerical model.
As the project progressed it became clear that the time needed to run a
single simulation dramatically limits the number of simulations that could be
run. Consequently, different approaches that could reduce simulation time
were also investigated.
Unlike the other material parameters, there is no test that can be used to
directly calibrate the damping. An array of numerical simulations were therefore
conducted testing different damping schemes. The comparison performed
between the numerical and experimental data showed that the numerical models
could not accurately simulate the experimental measurements of the scale
model dragline bucket. The numerical model did, however, predict many of the trends identified in the experimental simulation. With more realistic contact
models and better computer facilities, nonetheless, it is highly probable
that numerical models will be capable of simulating dragline bucket filling
accurately. Further study is, therefore, justified.
Description
Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2007.
Keywords
Dissertations -- Mechanical engineering, Theses -- Mechanical engineering, Draglines, Buckets (Excavating machinery)