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

The Korean Society of Marine Environment and safety (해양환경안전학회)
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A Study on the Structural Stability and Effectiveness of Rope Cutter for Ship's Propeller

선박추진기용 로프절단장치의 구조 안정성 및 효용성에 관한 연구

  • Kim, Jun-Soo (Korea Institute of Maritime and Fisheries Technology) ;
  • Seul, Youngyoon (Spursmtech. Inc) ;
  • Lee, Du-Yong (Korea Marine Equipment Research Institute) ;
  • Park, Kitae (Korea Institute of Maritime and Fisheries Technology) ;
  • Kim, Tae Hun (Korea Institute of Maritime and Fisheries Technology) ;
  • Choi, Jae-Hyuk (Division of Marine System Engineering, Korea Maritime and Ocean University) ;
  • Lee, Won-Ju (Division of Marine System Engineering, Korea Maritime and Ocean University)
  • 김준수 (한국해양수산연수원) ;
  • 설영윤 (스펄스엠텍) ;
  • 이두용 (한국조선해양기자재연구원) ;
  • 박기태 (한국해양수산연수원) ;
  • 김태훈 (한국해양수산연수원) ;
  • 최재혁 (한국해양대학교 기관시스템공학부) ;
  • 이원주 (한국해양대학교 기관시스템공학부)
  • Received : 2021.05.14
  • Accepted : 2021.06.28
  • Published : 2021.06.30
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Abstract

The scissor-type rope cutter is the most widely used amongst all kinds of commercially available rope cutters in Korea. In this study, we performed finite element analysis on the scissor-type rope cutter. We determined the structure of the cutter that would ensure its stable operation in various situations involving rope entanglement, and verified its effectiveness by testing it in the lab and in an actual ship. These investigations revealed that when the propeller shaft was not rotated by rope entanglement, the constant torque generated by the engine resulted in the torsion of the rope cutter and maximum deformation in the lower blade, which was not restricted by finite element analysis. With increasing blade thickness, the maximum values of deformation and equivalent stress decreased, resulting in a rise in the safety factor. At the constant blade thickness, the effect of the torque variations on the maximum equivalent stress and the maximum deformation is independent of the position of the external force of the rope cutter and decreases in direct proportion. The results of this study confirmed that the rope-cutter structure determined by analysis could lead to a hassle-free removal of ropes and fishing nets under all conditions and environments.

본 연구에서는 상용화된 로프절단장치 타입 중 국내에 가장 많이 도입되어있는 Scissor type을 대상으로 유한요소해석을 수행하여 다양한 로프 걸림 상황에서 안정성이 확보되는 적합한 구조 형태를 평가하였으며, 수조 실험 및 실선 실험을 통해 효용성을 검증하였다. 연구 결과, 로프 걸림에 의하여 프로펠러축이 회전하지 않을 경우 엔진에서 발생하는 지속적인 토크로 인하여 로프절단장치에 비틀림이 발생하고 유한요소 해석상 자유도가 구속되어 있지 않은 하부의 블레이드에서 가장 높은 변형이 발생하는 것을 확인하였다. 블레이드의 두께가 증가할수록 최대변형량은 줄어들고 최대응력은 낮아져 안전율이 증가하는 결과가 나타났으며, 동일한 블레이드 두께에서 토크의 변화량이 최대응력과 최대변형량에 미치는 영향은 로프절단장치의 외력이 미치는 위치와 무관하며 정비례하게 감소하는 것으로 나타났다. 해석 결과를 토대로 실시한 수조실험 및 실선실험 결과, 모든 조건과 환경에서 로프 및 어망이 원활하게 제거되는 것을 확인하였다.

Keywords

Acknowledgement

본 연구는 연구개발특구진흥재단의 지원을 받아 수행된 연구임.(2020-BS-RD-0134-01-202)

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