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A Study on the Methods for Finding Initial Equilibrium Position of a Lifting Block for the Safe Erection

블록의 탑재 안전성을 위한 초기 평형 자세 탐색 방법 연구

  • Chun, Do-Hyun (Department of Naval Architecture and Ocean Engineering, Seoul National University) ;
  • Roh, Myung-Il (Department of Naval Architecture and Ocean Engineering, and Research Institute of Marine Systems Engineering, Seoul National University) ;
  • Ham, Seung-Ho (Department of Naval Architecture and Ocean Engineering, Seoul National University) ;
  • Lee, Hye-Won (Department of Naval Architecture and Ocean Engineering, Seoul National University)
  • 전도현 (서울대학교 조선해양공학과) ;
  • 노명일 (서울대학교 조선해양공학과 및 해양시스템공학연구소) ;
  • 함승호 (서울대학교 조선해양공학과) ;
  • 이혜원 (서울대학교 조선해양공학과)
  • Received : 2018.11.07
  • Accepted : 2018.05.01
  • Published : 2018.08.20

Abstract

In a shipyard, block lifting is an important process in the production of ships and offshore structures. Block lifting is a sensitive process because lifting blocks have to be erected with exact positions and orientations. If we use a numerical method for the process, it is important to find tensions of wires and positions of equalizers to maintain the initial equilibrium position of the block. At this time, equations of motion of the block should be solved to calculate the initial equilibrium position of the block. Because the solving technique changes according to the number of equalizers, a suitable equation for the corresponding problem is required. In this study, three types of equations are proposed to find the initial equilibrium position of the block according to the number of equalizers. The Newton-Raphson's method is used to solve nonlinear simultaneous equations and the optimization method is used to determine the appropriate solution to the undetermined problem. To evaluate the applicability of the proposed methods, the dynamic simulations are performed using the tensions calculated from the proposed methods, and the results are discussed. The results show that the proposed methods can be effectively used to determine initial equilibrium position of the block for the block lifting.

Acknowledgement

Supported by : 서울대학교

References

  1. Davis, L., 1991. Handbook of genetic algorithms. Van Nostrand-Reinhold: New York, NY, USA.
  2. Deb, K. Pratap, A. Agarwal, S. & Meyarivan, T., 2002. A fast and elitist multiobjective genetic algorithm: NSGA-II. IEEE Transactions on Evolutionary Computation, 6(2), pp.182-197. https://doi.org/10.1109/4235.996017
  3. Goldberg, D.E., 1989. Genetic algorithms in search, optimization, and machine learning. Addison-Wesley: Boston, MA, USA.
  4. Ham, S.H., Roh, M.I., Lee, H.W. & Ha, S., 2015. Multibody dynamic analysis of a heavy load suspended by a floating crane with constraint-based wire rope. Ocean Engineering, 109, pp.145-160 https://doi.org/10.1016/j.oceaneng.2015.08.050
  5. Ham, S.H., Roh, M.I. & Lee, H.W., 2016. Simulation of load lifting with equalizers used in shipyards. Automation in Construction, 61, pp.98-111 https://doi.org/10.1016/j.autcon.2015.10.007
  6. Ham, S.H. et al., 2017. Development and validation of a simulation-based safety evaluation program for a mega floating crane. Advances in Engineering Software, 112, pp.101-116 https://doi.org/10.1016/j.advengsoft.2017.04.009
  7. Jung, D.W., 2016. Dynamic analysis of block lifting simulation with flexible body and development of user interface. Master's Thesis. Mokpo National University.
  8. Lee, H., Roh, M.I. & Ham, S.H., 2016. Block turnover simulation considering the interferences between the block and wire ropes in shipbuilding. Automation in Construction, 67, pp.60-75. https://doi.org/10.1016/j.autcon.2016.03.013
  9. Lee, S.M., Roh, M.I., Kim, K.S. & Ham. S.H., 2018. Optimum design of lug arrangement based on static and dynamic analyses for block lifting. Journal of Ship Production and Design, 34(2), pp.119-133. https://doi.org/10.5957/JSPD.160043
  10. Liu, Y. et al., 2017. Automatic design method and application in complex ship block lifting. Journal of Ship Production and Design, 33(4), pp.283-290. https://doi.org/10.5957/JSPD.150020