Dynamic responses of marine risers/pipes transporting fluid subject to top end excitations
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Publication Details
Author list: Leklong J., Chucheepsakul S., Kaewunruen S.
Publisher: Hindawi
Publication year: 2008
Start page: 105
End page: 112
Number of pages: 8
eISSN: 1745-4557
Languages: English-Great Britain (EN-GB)
Abstract
This paper deals with the dynamic responses to top end excitation of marine risers/pipes conveying internal fluid. The marine riser is often used as a flexible link between undersea bore head and subsurface offshore platform. The tidal waves and the changes of sea level consistently excite its top end connected to a floating vessel. In order to carry out the performance-based design of the marine risers, the evaluation of their dynamic responses to top end excitations is imperative. In this study, the marine riser is simulated using two-dimensional beam elements. Energy functional of the marine risers conveying fluids is derived from variational principle. Nonlinear equations of motion influenced by the nonlinear Morison waveform are obtained through Hamilton's principle. Investigation of the dynamic responses of marine risers to top end excitation is achieved using the finite element method and Newmark Average Acceleration Method. Interestingly, either beating or resonant phenomenon can be observed from the responses. It is also found that the top tension plays a major role in the increment of undamped frequencies of marine risers, while either the internal flow rate or the external hydrodynamic drag force remarkably affects the displacement amplitudes of the marine risers' dynamic responses. Copyright ฉ 2008 by The International Society of Offshore and Polar Engineers.
Keywords
Direct integration, Dynamic response, Finite elements, Internal fluid, Marine risers, Pipes, Top end excitation
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