Vibration response of the polar supply and research vessel the S. A. Agulhas II in Antarctica and the Southern ocean

• Main Author: Soal, Keith Ian
• Other Authors: Bekker, Annie, Stellenbosch University. Faculty of Engineering. Department of Mechanical and Mechatronic Engineering.
• Format: Thesis
• Language: English
• Published: Stellenbosch : Stellenbosch University 2014
• Subjects: Vibration (Marine engineering) > Measurement; Multivariate Statistical Analysis; Operational Modal Analysis; Icebreakers (Ships) > Vibration; Vibrations > Physiological effect; Structural fatique; UCTD; Southern Ocean; Antarc*; Antarctica; Antarktika
• Online Access: http://hdl.handle.net/10019.1/96058

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 ...