Comparison and validation of numerical methods to assess hydrodynamic loads on mechanical coupling of multiple bodies

Ghesmi, Mahdi; Graefe, Alexander von; Shigunov, Vladimir; Friedhoff, Benjamin; Moctar, Ould el

doi:10.1080/09377255.2018.1482100

Cited by 7 publications

(5 citation statements)

References 9 publications

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“…Efficient and sufficiently accurate prediction of motions of coupled bodies and loads on mechanical couplings is an important task in multiple applications. Recently, Ghesmi et al (2018) used contact elements to model hinge joints. This paper extended the application of contact elements for prismatic joints.…”

Section: Nonlinear Effectsmentioning

confidence: 99%

“…Recently, Ghesmi et. al [21] employed contact elements to represent hinge mechanical couplings. Application of contact elements eliminates the necessity to incorporate articulation constraints as in Lagrange multiplier and generalized coordinate methods and does not require system linearity as in mode expansion method.…”

Section: Introductionmentioning

confidence: 99%

“…Forces induced by contact elements can be integrated directly as external forces into motion equations [22]. In the present paper, we extended the application of contact element approach introduced and validated in [21] 1028 river-sea convoy was taken for validation purposes. The hydrodynamic package Ansys Aqwa [23] was used to simulate the convoy in time domain.…”

Section: Introductionmentioning

confidence: 99%

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Application of contact elements to represent prismatic mechanical couplings

Ghesmi

Moctar

2019

MATEC Web Conf.

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Accurate prediction of loads on mechanical couplings is crucial in assessment of loads on coupled structures and in optimization of mechanical coupling design. In this paper, a contact element model is introduced to represent prismatic joints. A twofold pushing convoy in shallow water was taken for time domain numerical simulations in regular waves. The prismatic joints interconnecting the convoy bodies allowed relative heave and pitch motions of the bodies relative to each other. The articulation forces and body motions were compared to model basin measurements to assess the reliability of contact element model. The contact element model could simulate the prismatic joints efficiently and it provided a suitable method to idealize free and suppressed modes at articulation locations.

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Section: Nonlinear Effectsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Application of contact elements to represent prismatic mechanical couplings

Ghesmi

Moctar

2019

MATEC Web Conf.

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“…Peng et al (2020) performed time-domain simulations of a hinged-type wave energy converter (WEC) in regular waves, in which the considered WEC unit consisted of four modules connected by rigid truss structures. For more studies dealing with mechanical connections between multiple bodies, see Diamantoulaki and Angelides (2010); Rogne (2014); Zhu et al (2017); Ghesmi et al (2019).…”

Section: Introductionmentioning

confidence: 99%

Seakeeping criteria of a moored and articulated multibody floating platform in head seas

2023

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Within the Space@Sea project, a multi-use floating concept was proposed by following the analogy of standardization to enlarge a floating platform using a multitude of smaller structures. An operability analysis must be performed to identify its seakeeping criteria and how the criteria limit its functionality. A two-step strategy is proposed to calculate the responses of the target floating concept in head waves, where nonlinearities of the mooring lines and mechanical joints are taken into account. The weakly nonlinear time-domain procedure relies on a diffraction-radiation model in the frequency domain. The motions of floating bodies are solved in the time domain, in which nonlinear Froude-Krylov and hydrostatic forces are estimated under instantaneous incident wave surface. Multibody interactions are resolved under consideration of catenary mooring lines and hinged joints. Wave-induced motions and loads are expressed in terms of transfer function for determining the limiting criteria, including the translational and rotational motions velocities and accelerations; relative motions, velocities and accelerations between module floaters; mooring tensions; as well as hinge forces. Assessments are carried out for various sea conditions against the prescribed values, for the chosen criteria, to address safety issues due to sever platform responses. Different operational requirements for trained workers and untrained passengers of motions and accelerations are taken into consideration. Results show that rotational motions have a significant influence on the platform’s seakeeping performance. Nevertheless, the root mean square (RMS) value of vertical acceleration dominates the comfort of persons onboard, defining the final limiting criterion of the entire platform.

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“…Various articulation techniques, such as hinge, prismatic, cylindrical, and screw joints [19] are possible. Newman [20], for example, treated wave effects on an array of five hinged rigid modules; Ghesmi et al [21], on articulated ships; Rogne [22], on hinged wave energy converters; Diamantoulaki and Angelides [23], on hinged floating breakwaters; and Zhu et al [24], on a floating offshore wind turbine with hinged structures. Reviewing research on MFSs showed that the hydrodynamic sensitivity of articulated multibody offshore structures has hardly been scrutinized, whereas hydrodynamics of multibody interactions and restrictions from mechanically modeled connectors has been considered.…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic Sensitivity of Moored and Articulated Multibody Offshore Structures in Waves

Jiang

Moctar

Schellin

2021

JMSE

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Within the framework of Space@Sea project, an articulated modular floating structurewas developed to serve as building blocks for artificial islands. The modularity was one of the keyelements, intended to provide the desired flexibility of additional deck space at sea. Consequently, the layout of a modular floating concept may change, depending on its functionality and environmental condition. Employing a potential-flow-based numerical model (i.e., weakly nonlinear Green function solver AQWA), this paper studied the hydrodynamic sensitivity of such multibody structures to the number of modules, to the arrangement of these modules, and to the incident wave angle. Results showed that for most wave frequencies, their hydrodynamic characteristics were similar although the floating platforms consisted of a different number of modules. Only translational horizontal motions, i.e., surge and sway, were sensitive to the incident wave angle. The most critical phenomenon occurred at head seas, where waves traveled perpendicularly to the rotation axes of hinged joints, and the hinge forces were largest. Hydrodynamic characteristics of modules attached behind the forth module hardly changed. The highest mooring line tensions arose at low wave frequencies, and they were caused by second-order mean drift forces. First-order forces acting on the mooring lines were relatively small. Apart from the motion responses and mooring tensions, forces acting on the hinge joints governed the system’s design. The associated results contribute to design of optimal configurations of moored and articulated multibody floating islands.

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Comparison and validation of numerical methods to assess hydrodynamic loads on mechanical coupling of multiple bodies

Cited by 7 publications

References 9 publications

Application of contact elements to represent prismatic mechanical couplings

Application of contact elements to represent prismatic mechanical couplings

Seakeeping criteria of a moored and articulated multibody floating platform in head seas

Hydrodynamic Sensitivity of Moored and Articulated Multibody Offshore Structures in Waves

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