Stochastic Dynamics of Marine Structures

Næss, Arvid; Moan, Torgeir

doi:10.1017/cbo9781139021364

Cited by 161 publications

(225 citation statements)

References 161 publications

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“…The sea states and their probability of occurrences can be defined from direct measurements or hindcast methods [11]. Significant wave height ( ) and peak spectral periods ( ) are usually sorted in the form of wave scatter tables.…”

Section: Long-term Modeling Of Wave Induced Vibration Of Risermentioning

confidence: 99%

On the selection of boundary conditions for top tensioned risers facing wave induced vibrations

Haghayeghi¹,

Ketabdari²

2018

J. vibroeng.

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Abstract. The severe ocean environment is obviously the source of many uncertain random loads on offshore structures. This harsh environment when acting on the slender top tensioned risers with high aspect ratio (L/D) causes multimodal vibration leading to fatigue failure. Thus, a reliable stress analysis procedure should be applied in the assessment of their long-term behaviors. This research is a study on the effect of boundary conditions on the total and local response of offshore risers due to loads in different sea states. A FEM code is developed for discretization of riser's structural model and was run for the riser of Amirkabir semisubmersible vessel for 87 sea states in the Caspian Sea and four boundary conditions. The results show that the most severe stresses in the riser don't happen essentially in the harshest environment. The comparison of boundary conditions shows that clamped-clamped boundaries lead to lowest stress values while the riser experiences a wider band of stress in the pinned-pinned boundary type. While the riser top end boundary condition highly influences the displacements and stresses even in the lower part of riser.

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Section: Long-term Modeling Of Wave Induced Vibration Of Risermentioning

confidence: 99%

On the selection of boundary conditions for top tensioned risers facing wave induced vibrations

Haghayeghi¹,

Ketabdari²

2018

J. vibroeng.

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“…Coles [110] provides an excellent general introduction to extreme response statistics. Naess and Moan [111] cover the application of extreme response statistics to marine systems.…”

Section: Extreme Response Statisticsmentioning

confidence: 99%

“…Other methods, such as all-peaks Weibull fitting, peaks-over-threshold methods and Weibull tail-fitting, attempt to use less data by focusing more on the tail of the distribution (see, e.g., [110,111]). Naess [112] developed a method that exploits an envelope process of some narrow-banded response.…”

Section: Extreme Response Statisticsmentioning

confidence: 99%

A Survey of WEC Reliability, Survival and Design Practices

Coe

Rij

2017

Energies

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A wave energy converter must be designed to survive and function efficiently, often in highly energetic ocean environments. This represents a challenging engineering problem, comprising systematic failure mode analysis, environmental characterization, modeling, experimental testing, fatigue and extreme response analysis. While, when compared with other ocean systems such as ships and offshore platforms, there is relatively little experience in wave energy converter design, a great deal of recent work has been done within these various areas. This paper summarizes the general stages and workflow for wave energy converter design, relying on supporting articles to provide insight. By surveying published work on wave energy converter survival and design response analyses, this paper seeks to provide the reader with an understanding of the different components of this process and the range of methodologies that can be brought to bear. In this way, the reader is provided with a large set of tools to perform design response analyses on wave energy converters.

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“…Such an uncertainty can be introduced by external stochastic excitations, e.g. energy harvesters or structural systems subjected to ocean waves, wind excitations, earthquakes, and impact loads [1][2][3][4][5][6]. For these cases, deterministic models cannot capture or even describe the essential features of the response and to this end, understanding of the system dynamics and optimization of its parameters for the desired performance is a challenging task.…”

Section: Introductionmentioning

confidence: 99%

A moment-equation-copula-closure method for nonlinear vibrational systems subjected to correlated noise

Joo

Sapsis

2016

Probabilistic Engineering Mechanics

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We develop a moment-equation-copula-closure method for the inexpensive approximation of the steady state statistical structure of strongly nonlinear systems which are subjected to correlated excitations. Our approach relies on the derivation of moment equations that describe the dynamics governing the two-time statistics. These are combined with a non-Gaussian pdf representation for the joint response-excitation statistics, based on copula functions that has i) single time statistical structure consistent with the analytical solutions of the Fokker-Planck equation, and ii) two-time statistical structure with Gaussian characteristics. Through the adopted pdf representation, we derive a closure scheme which we formulate in terms of a consistency condition involving the second order statistics of the response, the closure constraint. A similar condition, the dynamics constraint, is also derived directly through the moment equations. These two constraints are formulated as a low-dimensional minimization problem with respect to the unknown parameters of the representation, the minimization of which imposes an interplay between the dynamics and the adopted closure. The new method allows for the semi-analytical representation of the two-time, non-Gaussian structure of the solution as well as the joint statistical structure of the response-excitation over different time instants. We demonstrate its effectiveness through the application on bistable nonlinear single-degree-offreedom energy harvesters with mechanical and electromagnetic damping, and we show that the results compare favorably with direct Monte-Carlo simulations.

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Stochastic Dynamics of Marine Structures

Cited by 161 publications

References 161 publications

On the selection of boundary conditions for top tensioned risers facing wave induced vibrations

On the selection of boundary conditions for top tensioned risers facing wave induced vibrations

A Survey of WEC Reliability, Survival and Design Practices

A moment-equation-copula-closure method for nonlinear vibrational systems subjected to correlated noise

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