• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.1 s.118
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• pp.17-23
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• 2007

In this paper, the modified direct method employing beam transformation technique is proposed in order to efficiently calculate hydroelastic responses of floating structure. Since the proposed method expresses the displacements of three-dimensional structure with those of transformed beam which leads to small number of equations of motion, the method is numerically efficient compared to the conventional direct method. To verify the efficiency of the proposed method, a 500 m-long floating structure under wave loads is considered in numerical example. Displacements, bending moments, torsion moments and shear forces are calculated and computing time is examined. The results are also compared with those of the conventional direct method.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.6
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• pp.619-626
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• 2007

This paper presents an experimental study on deformations and force characteristics of flexible plates both in air and water. The focus is on the complicated interaction problem between the fluid and flexible structures. The displacements and forces of free oscillating plates are measured and compared with each others. The effects of several plate coefficients are investigated i.e. plate thickness, aspect ratio, plate area, plate width ratio, bending angle. For the verification of the experimental results, some of them are compared with numerical simulation and show reasonable agreements.

• Journal of the Society of Naval Architects of Korea
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• v.41 no.2
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• pp.55-60
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• 2004

This paper describes the estimation method of hull girder response of ships due to springing. To this aim, nonlinear springing effect on the hull girder is evaluated including vertical, horizontal, and torsional deformation of the hull. The Timoshenko beam model is used to calculate the stress distribution on the hull girder. The quadratic strip method is employed to calculate the hydrodynamic forces and moments on the hull. In order to remove the irregular frequencies, 'rigid lid'is adopted on the hull free surface level and hydrodynamic coefficients are interpolated for asymptotic values. The results of example calculation show a reasonable agreement with previous results for both symmetric and anti-symmetric responses.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.2
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• pp.168-174
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• 2008

To calculate the fluid-structure interaction(FSI) problem rationally, it should be the basic technology to analyse each domain of fluid and structure accurately. In this paper, a new FSI analysis algorithm was introduced using the 3D solid finite element for structural analysis and CFD code based on the HCIB method for viscous flow analysis. The fluid and structural domain were analysed successively and alternatively in time domain. The structural domain was analysed by the Newmark-b direct time integration scheme using the pressure field calculated by the CFD code. The results for example calculation were compared with other research and it was shown that those coincided each other. So we can conclude that the developed algorithm can be applied to the general FSI problems.

• Journal of the Society of Naval Architects of Korea
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• v.38 no.2
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• pp.26-32
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• 2001

In this paper, elastic responses of a floating structure in waves with a breakwater are presented. The method of source-dipole distribution is used to analyze the velocity potentials for the fluid region. The deflections of structure are expanded approximately in terms of natural mode functions of free-free beam. The model for present calculation is a floating plate with an length of 1000m and the hydroelastic responses for a floating structure with a straight breakwater are shown. The effects of distance between breakwater and structure, bending rigidity and relative length of regular waves are examined.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.4
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• pp.360-369
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• 2007

When a large ship is advancing in waves, ship undergoes the hydroelastic response, and this have influence on structural stability and the fatigue destruction etc. of ship. The main objective of this research is to develop an accurate and convenient method on the hydroelastic response analysis of ships on the real sea states. We analyzed hydroelastic responses, which is formulated by finite element method. The numerical approach for the hydroelastic responses is based on the combination of the three dimensional source distribution method, the dynamic response analysis and the spectral analysis method. The calculated results show good agreement with the experimental and calculated ones by Watanabe.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.3
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• pp.306-320
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• 2010

Modern ultra-large container carriers can be exposed to the unprecedented springing excitation from ocean waves due to their relatively low torsional rigidity. Large deck opening on the deck of container carriers tends to cause warping distortion of hull structure under wave-induced excitation, eventually leading to the higher chance of resonance vibration between its torsional response and incoming waves. To handle this problem, a higher-order B-spline Rankine panel method and Vlasov-beam FE model was directly coupled in the time domain, and the coupled equation was solved by using an implicit iterative method. In order to capture the complicated behavior of thin-walled open section girder, a sophisticated beam-based finite element model was developed, which takes into account warping distortion and shear-on-wall effect. Then, the developed beam model was directly coupled with the time-domain Rankine panel method for hydrodynamic problem by using the fixed-point iteration method. The developed computational scheme was validated through the comparison with the frequency-domain solution on the container carrier model in linear springing regime.

• Journal of Ocean Engineering and Technology
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• v.24 no.2
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• pp.34-40
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• 2010

When a large ship is advancing in waves, it undergoes hydroelastic response, which affects the structural stability and the fatigue destruction of the ship. Therefore, to predict an accurate hydroelastic response, it is necessary to conduct a thorough analysis of hydroelastic response, including fluid-structure interactions. In this research, the ship is divided into many hull elements, to calculate the fluid forces and wave exciting forces on each element. Using the three-dimensional source distribution method, the calculated fluid forces and wave exciting forces are assigned to nodes of the hull elements. The neighbor nodes are connected with elastic beam elements. We analyzed hydroelastic responses, using the finite elements method.

• Journal of the Korean Society for Marine Environment & Energy
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• v.1 no.2
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• pp.27-39
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• 1998

The interaction of monochromatic incident waves with a horizontal flexible membrane is investigated in the context of two-dimensional linear hydro-elastic theory. First, analytic diffraction and radiation solutions for a submerged impermeable horizontal membrane are obtained. Second, the theoretical prediction was compared with a series of experiments conducted in a two-dimensional wave tank at Texas A&M University. The measured reflection and transmission coefficients reasonably follow the trend of predicted values. Using the developed computer program, the performance of surface-mounted or submerged horizontal membrane wave barriers is tested with various system parameters and wave characteristics. It is found that the properly designed horizontal flexible membrane can be an effective wave barrier.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.9 no.4
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• pp.182-193
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• 1997

The interaction of monochromatic incident waves with a horizontal flexible membrane is investigated in the context of two-dimensional linear hydro-elastic theory. First, analytic diffraction and radiation solutions for a submerged impermeable horizontal membrane are obtained. Second, the theoretical prediction was compared with a series of experiments conducted in a two-dimensional wave tank at Texas A & M University. The measured reflection and transmission coefficients reasonably follow the trend of predicted values. Using the developed computer program, the performance of surface-mounted or submerged horizontal membrane wave barriers is tested with various system parameters and wave characteristics. It is found that the properly designed horizontal flexible membrane can be an effective wave barrier.