Thesis (MEng) -- Stellenbosch University, 2014. / ENGLISH ABSTRACT: Full scale measurements were conducted on the polar supply and research vessel
the S.A. Agulhas II during a 78 day voyage from Cape Town to Antarctica in
2013/2014. Investigations were conducted into the effect of vibration on human
comfort and the structural dynamic response of the vessel. Vibration measured
in the bridge of the vessel is found to have little effect on human comfort for a
standing person and is classified as not uncomfortable according to BS ISO 2631-1.
Structural fatigue as a result of vibration is found to reach levels where damage
is possible in the stern and where damage is probable in the bow during open
water navigation, according to ship vibration guidelines by Germanischer Lloyd.
Multivariate statistical analyses are performed to investigate the relationships between
multiple predictor variables and vibration response. Factor analysis revealed
data structure from which specific physical phenomena could be identified. Multivariable
linear regression models are developed to predict vibration response and
are found to provide more accurate predictions in open water than in ice. The
2-node, 3-node and 4-node normal bending modes of the structure are identified
using operational modal analysis while the vessel was moored in the harbour. The
natural frequencies, damping ratios and mode shapes are estimated and compared
using LMS Operational PolyMAX and ARTeMIS CCSSI. A comparison of operational
modal analysis results to the STX Finland finite element model show that
the vessel’s modes occur at lower frequencies than numerically predicted. Clear
potential is identified to further investigate structural vibration and operational
modal analysis algorithm development in future research. / AFRIKAANSE OPSOMMING: Volskaal metings was op die poolvoorsienings en navorsingskip die S.A. Agulhas
II uitgevoer tydens ’n 78 dae reis van Kaapstad tot Antarktika in 2013/2014.
Ondersoeke is uitgevoer met betrekking tot die effek van vibrasie op menslike gemak
en die strukturele dinamiese reaksie van die vaartuig. Vibrasie wat in die brug
van die skip gemeet is, het min invloed op menslike gemak vir ’n staande persoon
en word geklassifiseer as nie ongemaklik volgens BS ISO 2631-1. Strukturele vermoeidheid
as gevolg van vibrasie bereik vlakke waar skade moontlik is in die spieël
en waar skade waarskynlik is in die boog tydens navigasie in oop water, volgens
skip vibrasie riglyne deur Germanischer Lloyd. Meerveranderlike statistiese ontledings
is uitgevoer om die verhoudings tussen verskeie voorspellerveranderlikes
en vibrasieterugvoer te ondersoek. Faktorontleding het data struktuur openbaar
waaruit spesifieke fisiese verskynsels geïdentifiseer kan word. Multi-veranderlike lineêre
regressiemodelle was ontwikkel om vibrasie reaksie te voorspel en lewer meer
akkurate voorspellings in oop water as in ys. Die 2-nodus, 3-nodus en 4-nodus normale
buig modes van die struktuur is geïdentifiseer met behulp van operasionele
modale analise terwyl die skip vasgemeer in die hawe is. Die natuurlike frekwensie,
demping verhoudings en mode vorms is beraam en vergelyk met behulp van
LMS operasionele Polymax en ARTeMIS CCSSI. ’n vergelyking van operasionele
modale analise resultate en ’n STX Finland eindige element model toon dat die
vaartuig se modusse voorkom by laer frekwensies as wat numeries voorspel word.
Duidelike potensiaal is geïdentifiseer om strukturele vibrasie en die ontwikkeling
van operasionele modale analise algoritmes te ondersoek in toekomstige navorsing.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/96058 |
| Date | 12 1900 |
| Creators | Soal, Keith Ian |
| Contributors | Bekker, Annie, Stellenbosch University. Faculty of Engineering. Department of Mechanical and Mechatronic Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | xvii, 85 p. : ill. |
| Rights | Stellenbosch University |
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