Traditionally, the "Design Spiral" is used for the design of ships. The design spiral endorses the concept that the design process is sequential and iterative. Though this procedure was very effective over the years, the current trend of engineering demands that more stress be put on the exploration of optimum design. With the advancement of computing technologies, the onus has shifted from finding better calculation schemes to formulating an economically viable design scheme. One of the objects of the FIRST project funded by MARITECH was to develop a computer tool to give the best ship design using optimization techniques. This was entrusted to the Department of Aerospace and Ocean Engineering at Virginia Polytechnic Institute and State University in Blacksburg, Virginia. A container ship was chosen as the test case. The problem was tackled from an owner's point of view. Hence, the required freight rate was chosen as the objective. To achieve that goal, the team developed a package that consists of three modules: optimization, geometric and a performance evaluation module. Though these modules are essentially independent, the user has control over an overall manager. He can change the initial value of design parameters, set bounds and vary constraint bounds as per his needs. Though he does not know what goes on behind the user interface, he still feels secure with the design process because he has overall control. This sense of security breaks down when he has access to limited variables and constraints. A prototype MDO tool is developed based on Microsoft's COM framework using ATL. With this design, the modules can be modified with minimum programming effort. The user interface gives the user flexibility to manipulate relevant parameters that affect the design. A geometric shape manipulation scheme is developed in which the hull form was generated by blending two hull forms. This MDO tool is used to design a container ship with the required freight rate as the objective to be minimized. It is noticed that without a structural constraint, the design tends towards one with maximum length and beam. This led to unreasonably large ratios of B/D and L/D. A B/D constraint is applied to the design to get a better structural design. Results with this constraint enabled have pointed in the direction of adding two other design variables. This constraint increases the depth of the ship. With the increase in depth, the center of gravity of the ship also rises decreasing the GM of the ship. This lowering of GM adversely affects the GM constraint. The number of tiers on deck (NTd) is made a design variable to enable the optimizer to have the flexibility of manipulating the cargo carrying capacity. It was noticed that the ship is unable to have a high NTd because of the violation of the GM constraint. Hence, ballast has also been added as a design variable to reduce the center of gravity of the ship increasing the GM of the ship. This feature enables the optimizer to carry greater cargo on deck improving the objective function. An effort is made to analyze the efficacy of the MDO tool by varying various parameters that affect the design. Technology factors have been introduced which give an insight on effect of key parameters. They also reflect on future design trends. Three evaluation tools: sensitivity analysis, alpha plots and restart option have been incorporated in the design process to gauge the results of optimization. The effect of another structural constraint L/D was also investigated. This constraint tends to bring down the overall length and is inconclusive in its results. Further analysis of this constraint is needed to draw usable conclusions. The linear response surface approximation was eliminated and the original stepwise discontinuous TEU capacity function is employed in the later examples. It was found that the minimum of the required fright rate occurred at the lower limits of length and beam on each TEU capacity platform. A systematic search of TEU plateaus in the vicinity of the primary optimum was necessary to define the secondary optimum / Master of Science

This thesis describes a multidisciplinary design optimization approach to containership design. The method employs widely accepted regression equations for computing resistance, weights, building costs and operating costs. The current regulations governing freeboard and the Coast Guard wind heel criterion are included. The measures of merit used are the required freight rate and the return on investment. The system is flexible enough to allow changes in trade routes, shipyard and port parameters, and fuel costs. The weight-displacement balance is maintained by including draft as a design variable and imposing an equality constraint on weight and displacement rather than introducing an internal loop to calculate draft at each iteration. This speeds up the optimization process. The process takes into account the discrete container stowage issue. The carrying capacity (number of containers) is expressed as a continuous function of the principal dimensions by using a linear response surface fit that in turn makes the objective function continuous. Speed is a design variable. The optimum speed takes into account the compromise required between higher speeds that imply higher revenue and lower speeds that imply lower fuel costs. The optimizer used is the Design Optimization Tools (DOT) program from Vanderplaats Research and Development, Inc. Results employing the three different techniques provided in DOT have been obtained and compared. The optimum ship tends to be the largest ship in terms of length and beam. An optimum speed is identified. The three techniques provided in DOT give fairly consistent results, but once a good optimum point is identified in the design space, the sequential linear programming algorithm is found to be the most consistent method to converge to a local optimum. The objective function is found to be flat in the vicinity of the optimum that indicates that the designer is not confined to a severely restricted design space and has some freedom in designing the optimum ship. / Master of Science

Orientador: Aníbal Tavares de Azevedo / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Aplicadas / Made available in DSpace on 2018-08-27T17:30:28Z (GMT). No. of bitstreams: 1 Junqueira_Catarina_M.pdf: 2614874 bytes, checksum: b29c43ffaf65bf7db65e0296e74da20b (MD5) Previous issue date: 2015 / Resumo: A eficiência de um terminal portuário é essencial para permitir o incremento do fluxo de contêineres em uma cadeia global de suprimentos. Neste trabalho, é proposta a integração do problema de movimentação de contêineres no pátio com o problema do plano de estiva do navio. Na literatura é provado que ambos os problemas são NP-Completos, para tanto, é proposta a adaptação de um método que já foi empregado com sucesso na resolução do problema do plano de estiva: a representação por regras. As regras definem ao longo de n portos, como vai ocorrer a sequência de carregamento e descarregamento de contêineres e tem como objetivo reduzir o número de movimentos desnecessários. A contribuição prática dar-se-á pela redução na quantidade de informações necessárias para se representar a tomada de decisões através de um modelo matemático. Além disso, a representação por regras tem a grande vantagem de utilizar uma representação bastante compacta que assegura a geração de soluções factíveis. São apresentados os resultados obtidos com exemplos numéricos que mostram que, com baixo tempo computacional foi possível obter sequências de movimentos factíveis / Abstract: The efficiency of a port terminal is essential to allow the increase of the flow of containers in a global supply chain. In this work, it is proposed the integration of the problem of moving containers in the yard with the ship stowage plan problem. In literature it is proven that both problems are NP-Complet, therefore, it is proposed to adapt a method that has been successfully employed in solving the problem of the storage plan: the rules representation. The rules define over n ports, how the sequence of loading and unloading containers will occur and aims to reduce the number of unnecessary movements. The practical contribution is given by the reduction in the amount of information needed to represent the decision-making process through a mathematical model. In addition, the rules representation have the advantage of using a very compact representation that ensures the generation of feasible solutions. The results obtained with numerical examples show that with low computational time it has been possible to obtain sequences of feasible movements / Mestrado / Pesquisa Operacional / Mestra em Pesquisa Operacional