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dc.contributor.advisorPrice, G-
dc.contributor.authorMathisen, Jan-
dc.descriptionThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.en_US
dc.description.abstractSimulation techniques and a Volterra functional polynomial are applied as two alternative methods of calculating ship roll response to irregular waves. The roll motion is modeled by a single degree of freedom differential equation, with two alternative nonlinear damping functions. Estimation techniques are developed to obtain the coefficients of the damping functions from decay tests and from forced rolling tests. A linear plus quadratic form of damping function is found to be slightly preferable to a linear plus cubic form. The roll response process is found to be non-Gaussian, and characterised by negative values of the coefficient of kurtosis. Simulation results agree well with results obtained from the functional polynomial for low response levels, but show increasing disagreement as the response level increases, due to divergence of the functional polynomial representation. Analyses of results from model tests in irregular waves and from sea trials confirm the non-Gaussian nature of the roll response. A "constrained" form of the generalised gamma distribution function is found to provide an improved fit to the roll maxima and tothe roll minima, as compared to the Rayleigh distribution. The model tests also show some asymmetry in the roll response, which is not predicted by the theoretical model. It is suggested that this asymmetry may primarily be due to the combined effect of horizontal drift forces and the restraining system used to keep the model on station.en_US
dc.description.sponsorshipFinancial support was obtained from: Dr.Techn. Georg Vedeler's Fund for Ship Research; A.S Veritas Research; the Overseas Research Students - ORS Awards Scheme; and the Royal Norwegian Council for Scientific and Industrial Research.en_US
dc.publisherBrunel University School of Engineering and Design PhD Theses-
dc.titleAnalyses of experiments and a functional model for ship rollingen_US
Appears in Collections:Mechanical and Aerospace Engineering
Dept of Mechanical Aerospace and Civil Engineering Theses

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