Memorial University DAI: The angle dependence of the roll damping moment

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Title	The angle dependence of the roll damping moment
Author	Bennett, Peter
Description	Thesis (M.Eng.)--Memorial University of Newfoundland, 1990. Engineering and Applied Science
Date	1990
Pagination	viii, 106 leaves : ill.
Subject	Damping (Mechanics); Stability of ships
Degree	M.Eng.
Degree Grantor	Memorial University of Newfoundland. Faculty of Engineering and Applied Science
Discipline	Engineering and Applied Science
Language	Eng
Notes	Bibliography: leaves 104-106.
Abstract	A new approach to the analysis of the free roll decay curve, the Energy method, is examined in this paper and compared with two commonly accepted methods of analysis, the averaging technique of Krylov-Bogoliubov and the Perturbation method. The Energy method uses the equality of the rate of change of the total energy of the system to the rate of energy dissipation due to damping. This method was concluded to be the best method for analysis for three main reasons. 1) It uses the whole roll decay record in its analysis, not just the peak values, allowing for single cycle analysis and analysis of shorter roll decay records. 2) It can separate the influence of the angle and velocity dependent components of the roll damping moment. 3) It can handle non-linear restoring terms which makes it viable for large amplitude motion. -- The Energy method and the Krylov-Bogoliubov method were used to analyze stillwater roll decay test records. The results of these analyses indicate a strong angle dependence of the roll damping moment. The quadratic and cubic velocity dependent forms, which are actually functions of the roll angle, of the roll damping moment were shown to be the most viable forms for the roll damping moment. This supports the findings of a strong angle dependence. Stillwater roll decay tests with forward speed were performed and also indicate a strong angle dependence of the roll damping moment. Comparisons of forced roll tests with predictions of forced roll motion using coefficients derived from the stillwater roll decay analyses proved inconclusive.
Type	Text
Resource Type	Electronic thesis or dissertation
Format	Image/jpeg; Application/pdf
Source	Paper copy kept in the Centre for Newfoundland Studies, Memorial University Libraries
Local Identifier	76072887
Rights	The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission.
Collection	Electronic Theses and Dissertations
Scanning Status	Completed
PDF File	(10.73 MB) -- http://collections.mun.ca/PDFs/theses/Bennett_Peter.pdf
CONTENTdm file name	237014.cpd