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dc.contributor.authorGobat, Jason I.  Concept link
dc.date.accessioned2009-02-27T13:28:00Z
dc.date.available2009-02-27T13:28:00Z
dc.date.issued2000-06
dc.identifier.urihttps://hdl.handle.net/1912/2720
dc.descriptionSubmitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2000.en
dc.description.abstractGeometrically compliant mooring systems that change their shape to accommodate deformations are common in oceanographic and offshore energy production applications. Because of the inherent geometric nonlinearities, analyses of such systems typically require the use of a sophisticated numerical model. This thesis describes one such model and uses that model along with experimental results to develop simpler forms for understanding the dynamic response of geometrically compliant moorings. The numerical program combines the box method spatial discretization with the generalized- a method for temporal integration. Compared to other schemes commonly employed for the temporal integration of the cable dynamics equations, including box method, trapezoidal rule, backward differences, and Newmark’s method, the generalized-a algorithm has the advantages of second-order accuracy, controllable numerical dissipation, and improved stability when applied to the nonlinear problem. The numerical program is validated using results from laboratory and field experiments. Field experiment and numerical results are used to develop a simple model for dynamic tension response to vertical motion in geometrically compliant moorings. As part of that development, the role of inertia, drag, and stiffness in the tension response are explored. For most moorings, the response is dominated by inertial and drag effects. The simple model uses just two terms to accurately capture these effects, including the coupling between inertia and drag. The separability of the responses to vertical and horizontal motions is demonstrated and a preliminary model for the response to horizontal motions is presented. The interaction of the mooring line with the sea floor in catenary moorings is considered. Using video and tension data from laboratory experiments, the tension shock condition at the touchdown point and its implications are observed for the first time. The lateral motion of line along the bottom associated with a shock during unloading may be a significant cause of chain wear in the touchdown region. Results from the laboratory experiments are also used to demonstrate the suitability of the elastic foundation approach to modeling sea floor interaction in numerical programs.en
dc.description.sponsorshipDuring my initial three years of study I was supported by an Office of Naval Research Graduate Fellowship. More recently, including the time spent on the research described in this thesis, I have been supported by the Office of Naval Research under grant numbers N00014-92-J-1269 and N00014-97-1-0583.en
dc.format.mimetypeapplication/pdf
dc.language.isoen_USen
dc.publisherMassachusetts Institute of Technology and Woods Hole Oceanographic Institutionen
dc.relation.ispartofseriesWHOI Thesesen
dc.subjectOffshore structuresen
dc.subjectDeep-sea mooringsen
dc.subjectCables, Submarineen
dc.subjectAnchorageen
dc.subjectDynamicsen
dc.subjectDynamic testingen
dc.subjectMathematical modelsen
dc.titleThe dynamics of geometrically compliant mooring systemsen
dc.typeThesisen
dc.identifier.doi10.1575/1912/2720


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