In this thesis, an application program is made to simulate the behavior of a ship block under various crane works and to generate data of lug reactions and wire tensions. The program is based on a CAD program, Pro/ENGINEER.
A ship is composed of more than 100 ship blocks. In order to lift, move, turn, or put a ship block at a convenient location for assembling, workers in a shipyard use cranes, wires, and lugs temporarily attached to the block. In the procedure of lifting and turning a ship block with a crane, it is important to find suitable lug points and wires to do the handling efficiently and prevent accidents. Evaluation of forces in lugs and wires is necessary, but the problem is rather complex due to nonlinearity and nonuniqueness.
In the present development, the nonlinear system of equations for quasi-static equilibriums is derived and a Newton type solution method is adopted to solve the system. The importance of initial estimates to the solution is illustrated and two approaches are utilized and compared.
With the program developed in this thesis, users can assign lug points on the CAD model by mouse and choose various linking devices at each crane point. Users can try to simulate the motion for any prescribed conditions, compare the motion of the block and the reactions and choose appropriate lug points and the type of wires and lugs. The results can be animated and displayed frame by frame. Several cases are shown. A lifting procedure by a goliath crane, and a turnover procedure by a jib crane are examples. Based on the history of reactions at each lug point and wire tensions, analysis can be next made. Optimization of lug positions is still left as a topic of future work.