- Volume 55 Issue 4
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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)
- Received : 2018.11.07
- Accepted : 2018.05.01
- Published : 2018.08.20
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.
Supported by : 서울대학교
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