Study On The Midship Section Structure Optimization Of Yangtze River Multi-purpose Vessel Based On Genetic Algorithm And Particle Swarm Optimization

The Yangtze River runs through seven provinces and two municipalities in China.Yangtze River Shipping undertakes the transport of major bulk cargoes along the Yangtze River basin.The development of the Yangtze River Shipping plays an important role in the construction and development of the Yangtze River Economic Belt.The green development of the golden waterway of the Yangtze River is an important support for the sustainable development of the Yangtze River Shipping.Reducing ship pollution to the basin’s environment and transporting more cargoes with less fuel consumption are the basic requirements for ships which Sailing on the Yangtze River.Therefore,It is necessary to optimize the Yangtze River standard ship structural with some structural optimization techniques such as the weight loss or excellent material,and introduce the green gene into the ship structure,so that the ship structure product achieves the energy saving,material reduction,and safety design goals.As one of the three main ship types in the Yangtze River,it has important engineering application significance for getting the optimal structure of multi-purpose standard vessel.This article selects a Yangtze River-37(I)multipurpose vessel as the research object,combines the structural characteristics of the ship and the structure optimization theory,then,selects the midship section structure as the optimization object,and try to reduce the weight of multi-purpose cargo hold structure with some means.In order to improve the algorithm fast convergence and local search performance,this paper combines the genetic algorithm and the particle swarm algorithm,Then the improved genetic particle swarm algorithm and the double population genetic particle swarm algorithm are applied to solving the structural optimization problem of the multi-purpose ship.Finally,Using Patran&Nastran software to build the finite element model of cargo hold to calculate the structure stress,to check the strength of the optimized structure and verify the effectiveness of the optimization results.The main research content of this article is as follows:(1)Based on the basic theory and characteristics of genetic algorithm and particle swarm optimization algorithm,then the genetic algorithm and the improved two-population genetic algorithm are combined with the particle swarm optimization algorithm,finally,a Genetic Particle Swarm Optimization and Double Population Genetic Particle Swarm Optimization which with better optimization performancehave been proposed;(2)Established a mathematical model for the optimization of the mid-section structure size of the Yangtze River Waterline-37(I)Multipurpose Vessel,with the lightest weight per unit length of the cargo hold as the optimization goal and the cross-sectional area and plate thickness of the longitudinal aggregate in the middle section as the design variables,and combined with the "steel inland watercraft construction code" to establish the constraints of the optimization model,then the genetic algorithm,the genetic particle swarm optimization algorithm,and the double population genetic particle swarm optimization algorithm were used to optimize the ship structure.The three optimization algorithms respectively reduced the objective function by 5.11%.,5.90% and 6.70%.According to the optimization results of the three algorithms,the the double population genetic particle swarm optimization algorithm has better convergence performance in the process of ship structural optimization,and the genetic particle swarm algorithm is the second one.(3)According to the relevant specifications,using the MSC.PATRAN and MSC.NASTRAN software to build the the multipurpose vessel entire cargo hold finite element,determine its boundary conditions and working conditions,before the optimization of cargo tank and the improved double population genetic particle swarm optimization algorithm optimized cabin strength.The results show that the structural strength of the optimized cargo tank satisfies the requirements of the specification,indicating the adaptability and effectiveness of the double population genetic particle swarm optimization algorithm for solving the ship structural optimization problems.