• Journal of Aerospace System Engineering
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• v.12 no.5
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• pp.24-31
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• 2018

The objectives of this study is to carry out Bird strike analysis and tests of a blade antenna of aircraft. FEMs (Finite Element Models) were created for the analysis, while dummy and real antennas were used for the bird strike tests. In the analysis, birds were modeled with SPH (Smooth Particle Hydrodynamics) method, and the behaviors of the bird, antenna, and joint structure between antenna and aircraft fuselage were simulated with the FSI (Fluid-Structure Interaction) method. After the bird strike test was performed, the results of the analysis and test showed that they had a positive relationship. The damage of antenna and bolted joint was checked, and the structural integrity of the airframe was proved.

• Journal of Ocean Engineering and Technology
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• v.27 no.2
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• pp.53-58
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• 2013

Recently, some fluid-structure interaction (FSI) problems involving the fluid impact loads interacting with structures, such as sloshing, slamming, green-water, etc., have been considered, especially in the ocean engineering field. The governing equations for both an elastic solid model and flow model were originally derived from similar continuum mechanics principles. In this study, an elastic model based on a particle method, the MPS method, was developed for simulating the FSI problems. The developed model was first applied to a simple cantilever deflection problem for verification. Then, the model was coupled with the fluid flow model, the PNU (Pusan National University modified)-MPS method, and applied to the numerical investigation of the coupling effects between a cantilever and a mass of water, which has variable density, free-falling to the end of the cantilever.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.1
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• pp.71-78
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• 2015

The reliable sloshing assessment methods for LNG CCS(cargo containment system) are important to satisfy the structural strength of the systems. Multiphase fluid flow of LNG and Gas Compressibility may have a large effect on excited pressures and structural response. Impinging jet model has been introduced to simulate the impact of the LNG sloshing and analyze structural response of LNG CCS as a practical FSI(fluid structure interaction) method. The practical method based on fluid structure interaction analysis is employed in order to evaluate the structural strength in actual scale for Mark III CCS. The numerical model is based on an Euler model that employs the CVFEM(control volume based finite element method). It includes the particle motion of gas to simulate not only the interphase interaction between LNG liquid and gas and the impact load on the LNG insulation box. The analysis results by proposed method are evaluated and discussed for an effectiveness of FSI analysis method.

• Journal of the Society of Naval Architects of Korea
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• v.35 no.3
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• pp.71-78
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• 1998

Recently, modern long-stroke diesel engines with small number of cylinders have been installed for energy saving and simpler maintenance. These kinds of low speed diesel engine produce large torsional vibration in the shafting, which induces the excessive vibratory stresses in the shafting and large propeller thrust variation. This thrust variation excites vibrations of the shafting and superstructure in the longitudinal direction. Up to now the deteriministic analysis of coupled vibration of marine shafting system has been performed. In this paper probabilistic analysis method of the marine diesel propulsion shafting system under coupled axial and torsional vibrations is presented. For the purpose of this work, the torsional and axial vibration excitations of engine and propeller are assumed to be probabilistic while the lateral excitation is assumed to be deterministic. The probabilistic analysis is based on a response surface and Monte-Carlo simulation. Numerical results based on the proposed method are compared with results calculated using the conventional deterministic analysis method. The results obtained make it clear that the proposed method gives a substantial increase in information about shafting behaviour as compared with the deterministic method.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.5
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• pp.361-366
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• 2017

As the recent development of computing architecture and application software technology, real world simulation, which is the ultimate destination of computer simulation, is emerging as a practical issue in several research sectors. In this paper, metal plate motion in a square shock tube for small time interval was calculated using a supercomputing-based fluid-structure-combustion multi-physics simulation tool called Illinois Rocstar, developed in a US national R amp; D program at the University of Illinois. Afterwards, the simulation results were compared with those from experiments. The coupled solvers for unsteady compressible fluid dynamics and for structural analysis were based on the finite volume structured grid system and the large deformation linear elastic model, respectively. In addition, a strong correlation between calculation and experiment was shown, probably because of the predictor-corrector time-integration scheme framework. In the future, additional validation studies and code improvements for higher accuracy will be conducted to obtain a reliable open-source software research tool.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.6
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• pp.796-802
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• 2018

The effects of inner liquid sloshing on vessel motions are a well-known factor. It was investigated experimentally and numerically. In this regard, the study of many efforts to reduce natural phenomena of vessel motions by adopting special devices especially for roll motions. Among many devices, inserting baffles in the inner liquid tank is very common. In this study, one investigated the vessel motions with inner sloshing tanks with baffles inside. For the numerical simulation, one employed a dynamically coupled program between boundary-element-method-based vessel motion analysis program and a particle-based computational fluid dynamics program. Comparing corresponding experimental results validated the dynamically coupled program. The validated coupled program was used to simulate vessel motions, including sloshing effects with various lengths of inner baffles. The simulation results show that not only the filling ratio of inner liquid, but also the length of clearance due to baffles influenced the vessel motions. The significant point of this study was that the natural frequency of vessel motions can be maintained irrespective of the amount of filling ratio through adjustment of the clearance. In a future study, the effects of various numbers of baffles with various clearances would be conducted to percuss the possibility of vessel motion control with inner liquid sloshing effects.

• Journal of Navigation and Port Research
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• v.44 no.3
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• pp.264-274
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• 2020

The Ro-Ro ferry ship capsized and sank to the bottom of the sea because of the rapid turning for several reasons, such as lack of stability due to the center of gravity rise from the extension and rebuilding of the stern cabin, excessive cargo loading, and shortage ballast, poor lashing, etc. The purpose of this study was to investigate and analyze the cause of the ship's rapid flooding, capsizing, and sinking accident according to rapid turning scientifically and accurately using the Fluid-Structure Interaction( FSI) analysis technique. Several tests were conducted for this cause investigation of the flooding and sinking accident correctly and objectively, such as the realization of the accurate ship posture tracks according to the accident time using several accident movies and photos, the validation of cargo moving track, and sea water inflow amount through the exterior openings and interior paths compared with the ship's posture according to the accident time using the floating simulation and hydrostatic characteristics program calculation, and the performance of a full-scale ship flooding·sinking simulation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.6
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• pp.681-689
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• 2012

In this study, we performed a simulation of the dynamic response of a multibody system to calculate the tension acting on wire ropes connecting floating cranes and a heavy cargo such as a Giga Block weighing over 5000 tons when the cargo is salvaged using parallel connected floating cranes. In this simulation, we supposed that the motion of the floating cranes, barge ship, and heavy cargo has 6 degrees of freedom and that the interaction is determined by constraints among them. In addition, we considered independent hydrostatic and hydrodynamic forces as external forces acting on the floating cranes and barge ship. The simulation result can be a basis for verifying the safety of construction methods in which heavy cargo is salvaged by parallel connected floating cranes, and it can also be used to guide the development of such construction methods.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.1
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• pp.7-13
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• 2008

In this paper, the pumping performance of a piezoelectric valveless micropump is simulated with a commercial finite element analysis software, COMSOL Multiphysics. The micropump developed in the previous work is composed of a 4-layer lightweight piezo-composite actuator (LIPCA), a polydimethylsiloxane (PDMS) pump chamber, and two diffusers. The piezoelectric domain, structural domain and fluid domain are coupled in the simulation. Water flow rates are numerically predicted for geometric parameters of the micropump. Based on this study, the micropump is optimally designed to obtain its highest pumping performance.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.315-318
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• 2006

This paper concerns about coupled dynamic analysis of the deep-seabed mining system in launching operation. The dynamic behavior of mining system consisting of lifting pipe, buffer station, flexible conduit and self-propelled miner is simulated in time domain. The launching operation is divided into four critical phases: (1) deployment of miner and flexible conduit, (2) deployment of lifting pipe, flexible conduit and miner, (3) touch-down of miner, (4) final launching. The dynamic responses of sub-systems - miner, flexible conduit, buffer and lifting pipe - are analyzed in each launching phase. According to the changing periods of forced excitation at the top, the dynamic responses of sub-systems are diverse in their characteristics. It has been shown that the total integrated responses of sub-systems are strongly affected by the design parameters. Especially, the principal dimensions of flexible conduit seem to be significant in determining of the global response. Based on the simulation results, safe operation conditions are investigated.