An Optimization Model for Shell Plate Seam Landing Using Minimum Manufacturing Cost and a Solution by Genetic Algorithm

Abstract

At present, the landing of seams and butts on the ship hull surface, which plays the important role in the shipbuilding process, is still carried out based on the designers’ skill and experience. In this paper, a new optimization model and its solution method for the landing of seams and butts (for convenience, seam and butt are simply called seam) on the ship hull surface are proposed in order to improve the shipbuilding efficiency. The minimum manufacturing cost of ship hull shell plates (SHSPs) is the objective function, the rules and requirements for the seam position and the size of a single shell plate are the constraints, and the position and shape of the seam are the design variables. The manufacturing cost consists of the costs of cutting, face cutting, bending, and welding, which are calculated for a seam landing, and the strip method is applied to develop the curved shell plate in the bending cost calculation. We consider a shape optimization problem that the optimal solution is searched among the possible alternatives when the position and shape of the seams are changed and apply the genetic algorithm to the solution of this shape optimization problem. The proposed method is applied to a 4200 DWT bulk carrier and a fishing vessel to find the optimal solutions, and compared with the existing seam landings of the ships and the optimum solutions by Taguchi method. The calculation shows that the manufacturing cost by the proposed method for 4200 DWT bulk carrier is reduced by 5.8% and 4.5%, respectively, compared to the existing seam landing and Taguchi method, and by 6.6% and 4.8% for the fishing vessel, respectively. This shows that the proposed method is more effective than the designers’ experience and Taguchi method.