On the non-linear hydroelastic response in irregular head waves of a structural optimized container ship

2013 ◽  
pp. 79-90
Keyword(s):  
Container Ship ◽  
Head Waves ◽  
Non Linear ◽  
Hydroelastic Response

A Novel Solution to Compute Stress Time Series in Nonlinear Hydro-Structure Simulations

2015 ◽  
Author(s):  
Fabien Bigot ◽  
François-Xavier Sireta ◽  
Eric Baudin ◽  
Quentin Derbanne ◽  
Etienne Tiphine ◽  
...  
Keyword(s):  
Time Series ◽  
Frequency Domain ◽  
Time Domain ◽  
Hot Spot ◽  
Structural Response ◽  
Container Ship ◽  
Time Step ◽  
Computation Cost ◽  
Hull Girder ◽  
Non Linear

Ship transport is growing up rapidly, leading to ships size increase, and particularly for container ships. The last generation of Container Ship is now called Ultra Large Container Ship (ULCS). Due to their increasing sizes they are more flexible and more prone to wave induced vibrations of their hull girder: springing and whipping. The subsequent increase of the structure fatigue damage needs to be evaluated at the design stage, thus pushing the development of hydro-elastic simulation models. Spectral fatigue analysis including the first order springing can be done at a reasonable computational cost since the coupling between the sea-keeping and the Finite Element Method (FEM) structural analysis is performed in frequency domain. On the opposite, the simulation of non-linear phenomena (Non linear springing, whipping) has to be done in time domain, which dramatically increases the computation cost. In the context of ULCS, because of hull girder torsion and structural discontinuities, the hot spot stress time series that are required for fatigue analysis cannot be simply obtained from the hull girder loads in way of the detail. On the other hand, the computation cost to perform a FEM analysis at each time step is too high, so alternative solutions are necessary. In this paper a new solution is proposed, that is derived from a method for the efficient conversion of full scale strain measurements into internal loads. In this context, the process is reversed so that the stresses in the structural details are derived from the internal loads computed by the sea-keeping program. First, a base of distortion modes is built using a structural model of the ship. An original method to build this base using the structural response to wave loading is proposed. Then a conversion matrix is used to project the computed internal loads values on the distortion modes base, and the hot spot stresses are obtained by recombination of their modal values. The Moore-Penrose pseudo-inverse is used to minimize the error. In a first step, the conversion procedure is established and validated using the frequency domain hydro-structure model of a ULCS. Then the method is applied to a non-linear time domain simulation for which the structural response has actually been computed at each time step in order to have a reference stress signal, in order to prove its efficiency.

scholarly journals Impact of trim on added resistance of KRISO container ship (KCS) in head waves: An experimental and numerical study

2020 ◽  
Vol 211 ◽  
pp. 107594
Author(s):  
Emil Shivachev ◽  
Mahdi Khorasanchi ◽  
Sandy Day ◽  
Osman Turan
Keyword(s):  
Numerical Study ◽  
Container Ship ◽  
Added Resistance ◽  
Head Waves

Parametric Rolling in Regular Head Waves of the KRISO Container Ship: Numerical and Experimental Investigation in Shallow Water

2019 ◽  
Author(s):  
Manases Tello Ruiz ◽  
Jose Villagomez ◽  
Guillaume Delefortrie ◽  
Evert Lataire ◽  
Marc Vantorre
Keyword(s):  
Shallow Water ◽  
Water Depth ◽  
Water Waves ◽  
Failure Modes ◽  
Container Ship ◽  
Parametric Roll ◽  
Parametric Rolling ◽  
Wave Characteristics ◽  
Intact Stability ◽  
Head Waves

Abstract The IMO Intact Stability Code considers the parametric rolling phenomenon as one of the stability failure modes because of the larger roll angles attained. This hazardous condition of roll resonance can lead to loss of cargo, passenger discomfort, and even (in the extreme cases) the ship’s capsize. Studies as such are mostly conducted considering wave characteristics corresponding to wave lengths around one ship length (λ ≈ LPP) and wave amplitudes varying from moderate to rough values. These wave characteristics, recognised as main contributors to parametric rolling, are frequently encountered in deep water. Waves with lengths of such magnitudes are also met by modern container ships in areas in close proximity to ports, but with less significant wave amplitudes. In such areas, due to the limited water depth and the relatively large draft of the ships, shallow water effects influence the overall ship behaviour as well. Studies dedicated to parametric rolling occurrence in shallow water are scarce in literature. In spite of no accidents being yet reported in such scenarios, its occurrence and methods for its prediction require further attention; this in order to prevent any hazardous conditions. The present work investigates the parametric roll phenomenon numerically and experimentally in shallow water. The study is carried out with the KRISO container ship (KCS) hull. The numerical investigation uses methods available in literature to study the susceptibility and severity of parametric rolling. Their applicability to investigate this phenomenon in shallow water is also discussed. The experimental analysis was carried out at the Towing Tank for Manoeuvres in Confined Water at Flanders Hydraulics Research (in co-operation with Ghent University). Model tests comprised a variation of different forward speeds, wave amplitudes and wave lengths (around one LPP). The water depth was fixed to a condition equivalent to a gross under keel clearance (UKC) of 100% of the ship’s draft.

scholarly journals Investigation of Non-Linear Ship Hydroelasticity by CFD-FEM Coupling Method

2021 ◽  
Vol 9 (5) ◽  
pp. 511
Author(s):  
Zhe Sun ◽  
Guang-Jun Liu ◽  
Li Zou ◽  
Hao Zheng ◽  
K. Djidjeli
Keyword(s):  
Natural Frequency ◽  
Wave Length ◽  
Body Motion ◽  
Wave Frequency ◽  
Length Ratio ◽  
Frequency Wave ◽  
Frequency Structure ◽  
Hull Structure ◽  
Non Linear ◽  
Hydroelastic Response

With the increase of ship size, the stiffness of the hull structure becomes smaller. This means that the frequency of wave excitation tends to be closer to the natural frequency of the hull vibration, which in turn makes the hydroelastic responses more significant. An accurate assessment of the wave loads and motion responses of hulls is the key to ship design and safety assessment. In this paper, the coupled CFD (Computational Fluid Dynamics)-FEM (Finite Element Method) method is used to investigate the non-linear hydroelasticity effect of a 6750-TEU (Twenty-foot Equivalent Unit) container ship. First, by comparing the heave, pitch, and vertical bending moment at midship section (VBM4) against experimental results reported in the literature, the validity of the numerical method in this paper is illustrated. Secondly, the ship responses under different wave length–ship length ratio, wave frequency-structure natural frequency, wave steepness, and ship speeds are studied. It is found that the wave length–ship length ratio has a more important influence on the hydroelastic response than that from wave frequency-structure natural frequency ratio, and the effect of wave non-linearity will behave differently under different wave length–ship length ratio. The increase of rigid body motion caused by forward speed will not correspondingly increase the non-linearity of the hydroelastic response.

Numerical Simulations of KCS Parametric Rolling in Head Waves

2019 ◽  
Author(s):  
Shuang Wang ◽  
Junkai Wei ◽  
Xuanshu Chen ◽  
Liwei Liu ◽  
Zhiguo Zhang
Keyword(s):  
Failure Modes ◽  
Coupling Effect ◽  
Simulation Method ◽  
Rolling Motion ◽  
Stochastic Dynamic ◽  
Container Ship ◽  
Parametric Rolling ◽  
Ship Model ◽  
Head Waves ◽  
Wetted Area

Abstract As a type of the ship stability failure modes, parametric rolling has attracted more attention from many researchers in recent years because of a series of accidents due to ship instability, especially the instability of container ship. Parametric rolling is a complex nonlinear stochastic dynamic problem, which is often accompanied by large amplitude vertical motions of ships. At present, there are many difficulties in the research of ship parameter rolling, mainly including the nonlinearity of parameter rolling motion, the random variation of wetted area of the hull surface up to the incident wave waterline and the coupling effect of rolling, pitching and heaving. Nowadays, the potential flow theory is a common method to predict parametric rolling, but this method may generate results with low accuracy in some conditions. This paper describes a numerical simulation method based on in-house CFD code HUST-Ship to analyze parametric rolling motion of KCS (KRISO Container Ship) container ship model. The paper studies the occurring conditions of parametric rolling motion of KCS model and reveals the mechanism of parametric rolling.

Full-Scale Measurements on Hull Response of a Large-Container Ship in Service

2006 ◽  
Author(s):  
Kenichiro Miyahara ◽  
Ryuju Miyake ◽  
Norikazu Abe ◽  
Atsushi Kumano ◽  
Masanobu Toyoda ◽  
...  
Keyword(s):  
High Harmonic ◽  
Bending Moment ◽  
Full Scale ◽  
Linear Wave ◽  
Container Ship ◽  
Wave Loads ◽  
Non Linear ◽  
Large Container ◽  
Probability Density Distributions

In order to investigate hull responses of post-Panamax container ships in the actual sea, full-scale measurements on hull responses of a post-Panamax container ship in service were conducted. In linear wave domain, the probability density distributions of hull responses obtained by full-scale measurements were compared with the Rayleigh distributions to check on the range of the applicability, and comparisons with the long-term distributions of the longitudinal stress obtained by full-scale measurements and the direct structural analyses based on the wave loads analyzed by using the linear 3D Rankine source method were made to verify the accuracy. In non-linear wave domain, the measured longitudinal stresses showed the asymmetry of vertical bending moment. The long-term distributions of hull responses, which have the high harmonic components, obtained by full-scale measurements were compared with the numerical results analyzed by using non-linear methods to investigate the non-linearity on hull responses of container ship.

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