A dissertation submitted to the Faculty of Engineering, University
of the Witwatersrand, Johannesburg, in fulfillment of
the requirements for the degree of Master of Science in Engineering / It has been said that experimental modal analysis (EMA) "grew to prominence
because the engineering community was incapable of properly analyzing
the dynamics of commercially significant structures" [24]. The advent
of powerful theoretical methods, such as the Finite Element Method (FEM)
has not, however, resulted in the demise of EMA. In fact both FEM and
EMA have undergone rapid growth and the merging of the two into an effective
design and diagnostic tool has had a major impact on the engineering
community's approach to dynamics related problems. In this study, the
term dual has no mathematical connotations and is used to describe the
complementary use of the techniques of EMA and FEM. The mining industry,
worldwide, has experienced dynamics related problems in the operation
of conveyances in vertical shafts. A study undertaken in South Africa investigated
the behaviour of shaft steelwork and skips, resulting in a set of design
guidelines for future shaft steelwork designs. This work only investigated
the dynamic behaviour of skips. In this project, the ABAQUS and MODEL
SOLUTION FEM codes were used to construct models of a. mine cage. An
impact modal test was carried ant on the cage, using a GenRad 2515 CAT
system, An impact hammer, suitable for exciting large structures, and a
strain gauge force transducer were designed and built for the purpose of the
test. The natural frequencies and mode shapes obtained from both FEM
and EMA are compared by means of the modal assurance criterion (MAC).
The test data is used to tune the model to produce accurate results. The
model Could then be used (with minimal further test work) for predicting
the response of the structure to dynamic loading or the effects of structural
modifications. / Andrew Chakane 2020
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/28733 |
| Date | January 1990 |
| Creators | Grobler, Steven Robert |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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