Research Of Structural Optimization Design Of River-sea-going Ship Based On Combined Bending And Torsion Analysis

At present,the Yangtze River Economic Belt is one of the three key regional strategies of China.Relying on the development of the "golden waterway",it is conducive to optimizing the strategic layout of the Yangtze River industry,making the economy incline and develop towards the inland,and promoting the coordinated development of the region.As an important part of the Yangtze River shipping,the river-sea-going ship has the characteristics of no transfer and less cargo damage,which effectively improves the transportation efficiency and helps the Yangtze River shipping to maximize the benefits.In order to maintain the ship’s deadweight and meet the characteristics of shallow draught in inland waterways,river-sea-going ships are generally wide,flat and fat ships with large openings.This type of ship design makes the problem of bending and torsional strength of the hull more prominent.Therefore,in the structural optimization design of the river-sea-going ship,the ultimate bearing capacity of bending and torsion has become a problem that cannot be ignored.In order to give full play to the advantages of "large volume and low cost" of the river-ocean direct ship,this paper conducts a research on the structural optimization design of the 1140 TEU river-sea-going ship through the integration of the multidisciplinary optimization platform Isight,which is based on the requirements of design specifications,direct structural calculation requirements and bending-torsional ultimate strength requirements.The main research contents are as follows:(1)Structural optimization of mid-cross section based on design specifications.The influence of MIGA,ASA and PSO on the optimization results was compared and analyzed,and the design variables with high contribution rate to quality were screened through sensitivity analysis,which provided the basis for the selection of design variables in the following sections.(2)Structural optimization of parametric cabin model based on direct structural calculation.Firstly,the necessity analysis is carried out.Then,the ASA and the OLHS method are used for calculation respectively,and the design scheme that satisfies the design specification,the direct calculation of the structure and the lightest mass at the same time is obtained.Finally,the optimization effect and optimization efficiency of the two methods are compared.(3)Structural optimization of parametric cabin model based on ultimate bending and torsional strength.Selecting different bending-torsional combined loads to optimize the cabin model,the "single optimal solution","double optimal solution" and "three optimal solutions" are obtained respectively.Finally,the optimal solution of the optimization problem is determined by using the three optimal solution evaluation coefficient γ.Through the research of this paper,the following conclusions can be drawn:(1)The ultimate bending moment value of the "single optimal solution" obtained by the optimization of the model under M:T=7:3 is smaller than that under M:T=10:0,which is reduced by about 20%.Therefore,in the structural optimization design of the hull,the influence of the ultimate strength of bending and torsion should be considered,so as to ensure the accuracy of the optimization.(2)The optimal solution of the final optimization design scheme is determined by using the three-optimal solution evaluation coefficient γ relative value γ.In this scheme,the mass value is 1237.47 t,which is 5.5% lower than the initial mass.The ultimate bending moment value is 1.43E+12 MPa,which is 5.9% higher than the initial ultimate bending moment value,and the ultimate torque value is 2.75 E +11 MPa,which is 27.9%higher than the initial limit torque value.