Discrete Event Production Simulation and Optimization of Ship Block Erection Process
Nowadays, shipyards are making every effort to efficiently manage equipments and resources such as labourers, gantry cranes, transporters, steel and block stock yards, etc. The block erection scheduling of a gantry crane has thus far been manually performed by a manager of a shipyard. Such a scenario leads to undesirably long times for producing scheduling results. In addition, the quality of the scheduling results may not be optimal. To improve the overall process, block erection discrete event simulations have been developed in this study by using techniques of optimization.
modeFRONTIER has been selected for this study. The logic of the optimization loop has been set up in a graphical way, building up the workflow structure presented in section 3.2 by means of interconnected nodes. Lead time of the block erection process has been defined as objective function. Two design variables have been defined respectively the first erected block and the erection rule (by layer, by slice or by pyramidal propagation). No constraints have been added in the optimization workflow because the constraints are already included in the sequence generator algorithm. Simplex algorithm and a genetic algorithm have been tested during the optimization process.