• 제목/요약/키워드: Hydroelastic responses

검색결과 39건 처리시간 0.025초

Comparison of Numerical Analyses and Model Test for Evaluation on Hydroelastic and Higher-order Springing Responses of Fixed Cylindrical Structure

  • Kim, Hyun-Sung;Won, Younguk;Oh, Young Jae;Lee, Kangsu;Kim, Byoung Wan
    • 한국해양공학회지
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    • 제35권3호
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    • pp.191-202
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    • 2021
  • Studies on very large offshore structures are increasing owing to the development of deep sea, large-scale energy generation using ocean resources, and so on. The enlargement of offshore structures makes the hydroelastic effect and low natural frequency related responses important. Numerical analyses and model tests for hydroelastic and higher-order springing responses of fixed cylindrical structures are conducted in this study. The panel methods with and without the hydroelastic effect with shell elements, and the Morison analysis method with beam elements are applied. To observe the hydroelastic effect for structural strength, two structures are considered: bottom-fixed cylindrical structures with high and low bending stiffnesses, respectively. The surge motions at the top of the structure and bending stresses on the structure are observed under regular and irregular wave conditions. The regular wave conditions are generated considering the ratios of the cylindrical outer diameter to the wave lengths, and keeping the wave steepness constant. The model tests are performed in the three-dimensional ocean engineering basin in the KRISO (Korea Research Institute of Ships and Ocean Engineering). From the numerical and experimental results, in which the hydroelastic responses are only observed in the case of the structure with a low bending stiffness, it is confirmed that the hydroelastic responses are highly dependent on the structural stiffness. Additionally, the higher-order phenomenon on the specified wave condition is analyzed by observing the higher-order springing responses when the incident wave frequency or its multiples with the high wave height coincides with the natural frequency of the structure.

초대형 부유식 해양구조물의 유탄성 응답에 대한 해석 방법 (Analysis Methods of Hydroelastic Responses for a Very Large Floating Structure)

  • 이호영
    • 한국해양공학회지
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    • 제14권2호
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    • pp.19-27
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    • 2000
  • In this paper hydroelastic responses of a very large floating structure(VLFS) are studied theoretically. We have been developed the source and dipole distribution method and pressure distribution method to evaluate the hydrodynamic pressures. The problem of vertical structural responses due to waves are calculated by using finite element method(FEM) and modal expansion method of a free-free beam Hydroelastic responses of VLFS in waves are computed by four methods developed in this paper. As a result the theoretical results of motion responses show good agreements with experimental ones.

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시간영역에서 초대형 부유식 해양구조물에 대한 유탄성 응답 해석 (Hydroelastic Responses of a Very Large Floating Structure in Time Domain)

  • 이호영;신현경
    • 한국해양공학회지
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    • 제14권3호
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    • pp.29-34
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    • 2000
  • This paper describes transient responses of a very floating structure subjected to dynamic load induced by waves. A time domain method is applied to the hydroelastic problems for this purpose. The method is based on source-dipole and FEM scheme and on Newmark $\beta$ method to pursuit time step process taking advantage of memory effect. The present procedure is carried out to analyze hydroelastic responses in regular waves and impact responses due to dropping aircraft.

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규칙파중을 항행하는 선박의 유탄성응답해석 (A Hydroelastic Response Analysis of Ships with Forward Speed in Regular Waves)

  • 이승철;배성용
    • 동력기계공학회지
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    • 제14권5호
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    • pp.48-55
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    • 2010
  • When a large ship is advancing in waves, ship undergoes the hydroelastic response, which has influences on structural stability and the fatigue destruction etc. of the ship. Therefore, to predict accurate hydroelastic response, it is necessary to analyze hydroelastic response including fluid-structure interaction. In this research, a ship is divided into many hull elements to calculate the fluid forces and wave exciting forces on each elements using three-dimensional source distribution method. The calculated fluid forces and wave exciting forces are assigned to nodes of hull elements. The neighbor nodes are connected with elastic beam elements. We analyzed hydroelastic responses, and those are formulated by using finite element method. Particularly, to estimate the influence of forward speed on the hydroelastic responses, we use two different methods : Full Hull Rotation Method(FHRM) and Sectional Hull Rotation Method(SHRM).

반잠수식 초대형 해양구조물의 파랑중 탄성응답특성 (Hydroelastic Response Characteristics of a Very Large Offshore Structures of Somisubmersible Type in waves)

  • 구자삼;김경태;홍봉기
    • 한국해양공학회지
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    • 제13권4호통권35호
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    • pp.19-27
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    • 1999
  • To design a very large floating structure, such as a floating airport, we have to estimate the hydroelastic responses of a very large floating structure (VLFS) exactly. We developed the numerical method for estimating the hydroelastic responses of the VLFS. The developed numerical approach is based on a combination of the three-dimensional source distribution method, the wave interaction theory and the finite element method for structurally treating the space frame elements. The Numerical results of the hydroelastic responses and steady drift forces of a somisubmersible type offshore structure, which is supported by the 33(3 by 11) floating bodies, with various bending rigidities are illustrated.

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Numerical and experimental analysis of hydroelastic responses of a high-speed trimaran in oblique irregular waves

  • Chen, Zhanyang;Gui, Hongbin;Dong, Pingsha;Yu, Changli
    • International Journal of Naval Architecture and Ocean Engineering
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    • 제11권1호
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    • pp.409-421
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    • 2019
  • Investigation of hydroelastic responses of high-speed vessels in irregular sea state is of major interest in naval applications. A three dimensional nonlinear time-domain hydroelastic method in oblique irregular waves is developed, in which the nonlinear hydrostatic restoring force caused by instantaneous wetted surface and slamming force are considered. In order to solve the two technical problems caused by irregular sea state, the time-domain retardation function and Proportional, Integral and Derivative (PID) autopilot model are applied respectively. Besides, segmented model tests of a high-speed trimaran in oblique waves are performed. An oblique wave testing system for trimarans is designed and assembled. The measured results of main hull and cross-decks are analyzed, and the differences in distribution of load responses between trimarans and monohull ships are discussed. Finally, from the comparisons, it is confirmed that the present concept for dealing with nonlinear hydroelastic responses of ships in oblique irregular waves is reliable and accurate.

강성분포의 변화가 초대형 부유식 구조물의 유탄성응답에 미치는 영향 고찰 (Influences of Stiffness Distributions on Hydroelastic Responses of Very Large floating Structures)

  • 김병완;경조현;홍사영;조석규
    • 대한조선학회논문집
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    • 제42권3호
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    • pp.220-232
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    • 2005
  • Influences of stiffness distributions on hydroelastic responses of very large floating structures (VLFS) are studied in this paper. Hydroelastic responses are calculated by direct method employing higher-order boundary element method (HOBEM) for fluid analysis and finite element method (FEM) for structure analysis. In structural analysis using FEM, Mindlin plate elements are used. An 1 km-long VLFS with uniform stiffness and modified VLFS with varying stiffness distributions are considered in numerical analysis. Responses of VLFS increase in flexible parts and decrease in stiff Parts. Reduction degree of displacements of VLFS with stiffened center is larger than that of VLFS with stiffened sides.

다방향불규칙파중 선박의 유탄성응답해석 (A Hydroelastic Response Analysis of Ships in Multi-Directional Irregular Waves)

  • 이승철;이창호;조효제;구자삼
    • 대한조선학회논문집
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    • 제44권4호
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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.

부유식 가두리 양식장의 파랑중 유탄성 응답 해석 (A Hydroelastic Analysis of a Floating Fish Cage in Waves)

  • 최윤락;여환태
    • 한국해양공학회지
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    • 제23권6호
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    • pp.7-11
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    • 2009
  • The dynamic responses and drift forces in waves of a floating circular fish cage are analyzed considering hydroelastic effects. The method of generalized mode is used to calculate the hydroelastic responses of the floater of cage. The elastic mode shapes, generalized mass, and stiffness in dry mode are evaluated by using a structural analysis code. The higher-order boundary element method is adopted to analyze the interaction between fluid and deformable structure. Some results of vertical motions and drift forces are shown and compared with those for a rigid body.

드릴쉽의 유탄성 응답해석 (A Hydroelastic Response Analysis of Drillships in Waves)

  • 구자삼;조효제
    • 동력기계공학회지
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    • 제8권4호
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    • pp.49-56
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    • 2004
  • To design very large ships, such as very large drillships, we have to estimate the hydroelastic responses of the very large ships in waves. A numerical procedure is described for estimating the hydroelastic responses of very large ships advancing with slow speed in waves. The developed numerical approach is based on a combination of the three-dimensional source distribution method and the finite element method, including fluid-structure interaction by regarding a very large ship as many hull elements connected with elastic beam elements. Numerical results are compared with experimental and numerical ones obtained in the literature. The results of comparison confirmed the validity of the proposed approach.

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