Shape And Size Coupling Optimization Research On Ore Carrier’s Hatch Corner

Large deck openings often cause severe stress concentrations due to the longitudinal discontinuous of the deck structure and sudden changes in geometry at the corners of the openings.Therefore,the hatch corner must be reasonably strengthened to prevent it from being damaged by excessive stress during voyage.Therefore,the shape and size of the hatch corner structures need to be reasonably optimized.In this paper,the hatch corner of a 250 KDWT ore carrier is used to study the optimization of the stress concentration of hatch corners.First of all,the construction method of sub-model of hatch corners that suitable for optimization is studied.In the optimization process,repeated calculations of the corner stress are needed,so the sub-model method is chosen to reduce the calculation cost.In this paper,the principles and methods for selecting sub-models suitable for optimization are studied,and the hatch corner sub-model is constructed accordingly,which ensures its accuracy in the optimization process and can greatly reduce the calculation cost.Secondly,the screening method of multiple load cases of the ore carrier is studied.In this paper,based on whether the maximum stress that can be achieved by the corner in the optimal design domain exceeds the allowable stress,eight dangerous load cases are selected from 56 standard load cases,which greatly reduced the work while ensuring the optimization effect.Then,aimed at the defects of previous methods that only the shape of the corner bracket is optimized when optimizing the hatch corner,a shape-size coupling hatch corner optimization method is proposed.The shape of hatch corner and the size of surrounding structures are optimized together so the mass distribution is more reasonable,and the maximum stress of the hatch corner is reduced more under the same mass constraints.Finally,the ship structure optimization algorithm is improved.Aiming at the characteristics of artificial bee colony algorithm（ABC）that it converges fast but is easy to fall into local optimum,the simulated annealing algorithm（SA）mechanism is introduced to improve it.The effectiveness of the improved algorithm is verified by mathematical examples,and the algorithm is successfully applied to the hatch corner optimization problem.The optimal solution is achieved in fewer iterations by the improved algorithm,which proved the applicability of the method in the optimization problems of local ship structures.