Study on optimal design of hatch cover via a three-stage optimization method involving material selection, size, and plate layout arrangement

The rising prices of materials for ship construction is one of the primary problems faced by global shipbuilding industries. A potential solution is to reduce the material cost through a structure optimization technique. In this study, the plate material and stiffener types, plate thickness, and plate layout are optimized in order to minimize the cost of materials. The genetic algorithm (GA) is a popular optimization technique for determining design variables. However, the GA is not suitable for dealing with continuously changing design variables, such as plate thickness. Hence, this study proposes a three-stage optimization method that consists of the optimization of plate material and stiffener types, plate thickness, and plate layout. The first and second stages are part of an integrated process called the hybrid GA, which starts with the plate material and stiffener-type selections, and then performs plate thickness optimization. The hybrid GA is effective in simultaneously determining design variables with different characteristics, such as the first - and second-stage problems. The last stage is layout optimization in which the plate material and stiffener types handled in the previous stage are considered to have been decided, thereby resulting in minimal effort during this stage.