Efficient block assembly scheduling is very important for building ships in the shortest possible time with efficient use of the facilities and resources of shipyards. Process planning is usually focused on determining the precedence constraints and weight factors of appropriate assembly units and tasks, but previous studies have mainly dealt with manufacturing processes such as welding.
The hull is a complex structure, so the deformation and stress generated during welding are also complex. The confinement of deformation during welding will increase residual stress, whereas the freedom of deformation will increase residual strain, making it difficult to assemble hull blocks. Therefore, the longitudinal strength of a hull must be taken into account when assembling it.
Ro Un Hyok, a researcher at the Faculty of Shipbuilding and Ocean Engineering, has proposed a process planning method based on the determination of precedence constraints and weighting factors for hull block assembly scheduling, taking into account the longitudinal strength of hulls.
According to the practical situation where precedence constraints and machine constraints exist, he proposed a mathematical model for hull block assembly scheduling, and a solution algorithm based on Lagrangian relaxation.
By addressing the precedence constraints based on assembly sequence and weight factor determination according to welding method in the hull block assembly process, he has laid a theoretical basis for process planning for block assembly scheduling, and he developed mathematical modeling and solution methods for these problems.
The results of the practical examples show that the proposed method provides rapid and effective solutions and it can be applied to the industry.
© 2021 Kim Chaek University of Technology