On the Dynamic Analysis of Multi-Component Mooring Lines

Nakajima, Toshio; Motora, Seizo; Fujino, Masataka

doi:10.4043/4309-ms

Cited by 32 publications

(22 citation statements)

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“…For instance, the OCIMF has met these design conditions at many port terminals worldwide (OCIMF, 2008). Nonetheless, when waves are the dominant action, to carry out a static analysis makes no sense and a dynamic analysis is needed instead (Nakajima et al, 1982;Natarajan and Ganapathy, 1995).…”

Section: Mooring Analysesmentioning

confidence: 99%

A Review of Ship Mooring Systems

Villa

Carral²,

Fraguela

et al. 2017

brod

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The physical principle that governs how ships are moored to a port has changed little over the years. Nevertheless, in recent decades, there have been developments in maritime transport towards increased vessel dimensions and operations in specialist terminals. These trends mean that offshore ports and mooring systems have to face more challenging conditions in terms of the waves, wind and drift current. At the same time, pier side port loading and unloading systems place demands on the mooring system, which must immobilise ships better. In this situation, the mooring system's own equipment, such as lines, deck fittings and mooring winches, must also evolve to work alongside new port devices. It is also necessary to point out that changes in mooring will take place in subsequent years. These innovations in attaching the ship to the pier will be highlighted here as they mark a significant change in mooring and pier components.

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Section: Mooring Analysesmentioning

confidence: 99%

A Review of Ship Mooring Systems

Villa

Carral²,

Fraguela

et al. 2017

brod

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“…By now, several models of seabed mechanics have been proposed [6,[9][10][11] . In this paper, we proposed a new kind of seabed model, which can account for rebound, friction, impact in three dimensions.…”

Section: Seabed Modelmentioning

confidence: 99%

“…Thomas et al [10] described a more detailed model through the use of lumped mass method; their model accounted for both friction and soil suction; the liftoff and grounding of mooring lines were also taken into consideration based on the prior formulations of Nakajima et al [11] and Dutta [12] . Liu et al [13] used numerical simulations to study the effect of friction between the line and sea floor from the time and frequency domains, and concluded that friction due to in-plane motion does contribute to mooring line damping depending on the excitation amplitude.…”

Section: Introductionmentioning

confidence: 99%

A study on dynamic response of cable-seabed interaction

Wang

Huang

Deng

et al. 2009

J. Shanghai Jiaotong Univ. (Sci.)

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A numerical method is developed to investigate the dynamic response of cable-seabed interaction in this paper. The motion of cable is described by the Lumped Parameter Method, while the seabed, unlike the prevailing simplified model of elastic foundation, is modeled as an irregular continuous rigid surface with rebound and friction existing, and the forces exerted by the seabed consist of normal counterforce and isotropic tangential Coulomb friction resistance. To describe the detailed dynamic response, two coefficients are introduced by analogy with the theory of rigid body collision with friction. The cable-seabed kinematic and dynamic contact conditions are formulated subsequently, and are used to incorporate the seabed effect into the cable dynamics to produce a set of ordinary differential governing equations. In this paper, we employ 4th order Runge-Kutta method to solve these equations. Several simulation cases are presented to illustrate the seabed effect. The results show that friction and impact have a prominent influence on the statics and dynamics of the cable.

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“…This approach is only valid for small dynamic motions about the static touchdown point. A second method is the lift-off and grounding approach described by Nakajima et al [66] and Thomas [90]. In this method, the mass of the discrete nodes or elements is reduced to zero as they approach the bottom.…”

Section: Forcing Boundary and Materials Effectsmentioning

confidence: 99%

The dynamics of geometrically compliant mooring systems

Gobat¹

2000

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Geometrically 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-α 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-α 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.

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On the Dynamic Analysis of Multi-Component Mooring Lines

Cited by 32 publications

References 0 publications

A Review of Ship Mooring Systems

A Review of Ship Mooring Systems

A study on dynamic response of cable-seabed interaction

The dynamics of geometrically compliant mooring systems

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