Research On The Midship Section Structure Optimization Of River-to-sea Ships Based On Ultimate Strength

Because of its advantages in business cycles and economic, the research on thestructure optimization of river-to-sea ships is becoming a hot issue. Based ondiscussion and review of ultimate strength of ship hulls and optimization mechanismand implementation method of hull structures, this paper takes the weight of midshipsection structure of a river-to-sea ship as the optimization goal. In accordance with‘River-to-Sea Construction Specifications’, optimization strategy and implementationapplied for the structure optimization of river-to-sea ships is studied with presentmature optimization design platform which is based on the ultimate strength. Themain contents and results are as follows:(1)By means of the study of ultimate strength calculation methods, this paperuses simplified and nonlinear finite element method as the ultimate strengthcalculation method, and introduces the calculation process of simplified method indetail. According to the characteristics of ship structures and existing researchachievements of structure optimization, simulated annealing algorithm is selected asoptimization algorithm. The calculation and analysis of optimization model iscompleted by optimization design platform Isight.(2)Based on the principle of simplified calculation method of ultimate strength,the simplified program is wrote using Fortran language. This article completes thefactors analysis of the grillage structure unit using the simplified program in advance.Through the comparison of theory and results of different methods of design ofexperiments, Optimal Latin hypercube design is chosen for sampling and sensitivitystudy. The structure elements of midship section of river-to-sea ships are analyzed.Taking the result of factors research of grillage structure unit into consideration, thedesign variables, constraints and objective of the optimization of midship sectionstructures are confirmed. Then, the sensitivities of midship section structures arecalculated. According to the sensitivity results, this paper eliminates some variablesand makes the preliminary optimization calculation.(3)Based on the parametric thought, this article establishes the model ofparametric finite element modeling and calculation for the midship section structures of river-to-sea ships using the secondary development scripting interface of thenonlinear finite element software Abaqus which is compiled by Python language.Combining with the above research results, this paper uses the optimization strategythat applying the approximation model, which is obtained through design ofexperiments, to complete the optimization calculation. It builds and calculates theoptimization model of midship section structures based on approximation model.Through the organization and verification of optimization results, the optimal midshipsection structure of river-to-sea ship based on ultimate strength is determined finally.