해양환경안전학회지 (Journal of the Korean Society of Marine Environment & Safety)

  • 제24권2호
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  • Pages.140-145
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  • 2018
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  • 1229-3431(pISSN)
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  • 2287-3341(eISSN)
해양환경안전학회 (The Korean Society of Marine Environment and safety)
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선박 계류시스템의 종방향 외력하의 비선형 동적거동 해석

Dynamical Analysis of the Mooring Vessel System Under Surge Excitations

  • 이상도 (한국해양대학교 대학원) ;
  • 유삼상 (한국해양대학교 기계공학부)
  • Lee, Sang-Do (Graduate School of Korea Maritime and Ocean University) ;
  • You, Sam-Sang (Division of Mechanical Engineering, Korea Maritime and Ocean University)
  • 투고 : 2018.02.13
  • 심사 : 2018.04.27
  • 발행 : 2018.04.30
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초록

본 연구는 두점식 선박 계류시스템의 종방향 외력에 대한 비선형 동적거동 해석을 수행하였다. 특정 입력 매개변수에 대한 카오스 운동과 한계주기궤도 등의 비선형 거동의 특성을 연구하였다. 주로 비선형복원력은 계류시스템의 강한 비선형성과 동적거동의 다양성을 제공한다. 계의 운동방정식 시뮬레이션에 사용된 수치 적분기는 4차 룽게쿠타법이다. 외력진폭과 주파수를 변화시킬 때 분기 그림과 동적불안정 현상들을 볼 수 있다. 외력의 주파수(진동수)가 0.4 rad/s인 경우 수많은 혼돈상태 점들 사이에 주기창이라 불리는 안정적인 주기해가 관측된다. 주파수가 0.7 rad/s인 경우는 외력진폭이 1.0을 초과할 때 혼돈 영역이 갑자기 증가한다. 주파수가 1.0 rad/s인 경우는 주파수가 0.4 rad/s 및 0.7 rad/s인 경우와 비교해 볼 때, 혼돈 운동이 약화된다. 아울러, 두점식 계류시스템은 각 매개변수에서 준주기 운동, 한계주기궤도, 대칭성의 깨짐과 같은 다양한 정상상태의 궤적이 관측된다.

This paper deals with the dynamical analysis of a two-point mooring vessel under surge excitations. The characteristics of nonlinear behaviors are investigated completely including bifurcation and limit cycle according to particular input parameter changes. The strong nonlinearity of the mooring system is mainly caused by linear and cubic terms of restoring force. The numerical simulation is performed based on the fourth order Runge-Kutta algorithm. The bifurcation diagram and several instability phenomena are observed clearly by varying amplitudes as well as frequencies of surge excitations. Stable periodic solutions, called the periodic windows, can be obtained in succession between chaotic clouds of dots in case of frequency ${\omega}=0.4rad/s$. In addition, the chaotic region is unexpectedly increased when external forcing amplitude exceeds 1.0 with the angular frequency of ${\omega}=0.7rad/s$. Compared to the cases for ${\omega}=0.4$, 0.7rad/s, the region of chaotic behavior becomes more fragile than in the case of ${\omega}=1.0rad/s$. Finally, various types of steady states including sub-harmonic motion, limit cycle, and symmetry breaking phenomenon are observed in the two-point mooring system at each parameter value.

키워드

참고문헌

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피인용 문헌

  1. Dynamical Rolling Analysis of a Vessel in Regular Beam Seas vol.24, pp.3, 2018, https://doi.org/10.7837/kosomes.2018.24.3.325
  2. Sliding Mode Control with Super-Twisting Algorithm for Surge Oscillation of Mooring Vessel System vol.24, pp.7, 2018, https://doi.org/10.7837/kosomes.2018.24.7.953
  3. Active Stabilization for Surge Motion of Moored Vessel in Irregular Head Waves vol.26, pp.5, 2020, https://doi.org/10.7837/kosomes.2020.26.5.437