Study On Structure Optimization Design Of Liquefied Natural Gas Ship With 174,000m~3

With the current energy situation is increasingly tense,people gradually look from the traditional oil,coal,transferred to clean,efficient,high-quality natural gas.The growth in demand for liquefied natural gas has also further boosted the volume of trade in liquefied natural gas vessels.But with the increase in demand,liquefied natural gas ship ship type is also growing,construction costs are gradually increased.Therefore,in order to reduce the cost of ship construction,to carry out the structure of liquefied natural gas carrier optimization work is of great significance.In this paper,a series of studies were carried out on the structural optimization design method with 174,000m3 LNG carrier.The method of structural optimization design for thin membranefilm liquefied natural gas carriers is selected.On this basis,the genetic algorithm in selection,crossover and mutation,iterative improvement,improved genetic algorithm(GA);using the pheromone updating principle of ant colony algorithm(ACO)is improved,by ant colony system(ACS).Based on the improved genetic algorithm and ant colony system(ACS)algorithm,an improved genetic ant colony system(GA-ACS)algorithm is proposed.The improved genetic algorithm and improved genetic ant colony system algorithm are used to optimize the structure of the liquid cargo tank structure of the thin film liquefied natural gas carrier by using MATLAB software,and the optimization results are obtained.Finally,the reliability improved genetic algorithm-ant colony system for verification,for cargo hold strength before and after optimization optimization are calculated and analyzed by using the finite element software.Liquefied natural gas carriers are the subjects of study,.The main contents of this paper are as follows :(1)Based on the theory knowledge of genetic algorithm,the selection,crossover,mutation and iteration of genetic algorithm are improved,and the improved genetic algorithm is obtained.The structural optimization of thin film liquefied natural gas carriers is calculated by using the improved genetic algorithm.First select the 174,000m3 LNG tanker midship section area,followed by vertical plate minimum as the objective function,finally "membrane type LNG carriers inspection guide" specification establishes constraints for structure optimization calculation of the improved genetic algorithm by using MATLAB software,obtained the optimized reduced cross-sectional area 3.8%.(2)Based on the basic theory and basic flow of Ant ColonyOptimization(ACO),the ant colony algorithm is improved,and the improved Genetic — Ant Colony System Optimization(GA — ACS)is used to analyze the cross.The profile of the profile is optimized,and the optimized cross-sectional area is reduced by 8%,which is better than that used of the improved genetic algorithm.(3)Using MSC.PATRAN software to build the three-dimensional finite element model of cargo hold,by analyzing the characteristics of LNG ship's force,determine its boundary conditions and working conditions,before the optimization of cargo tank and the improved GA—ACS optimized cabin strength The results show that the strength of the optimized cargo tank compartment meets the specification requirements.