Diante do moderno paradigma de projeto otimizado de grandes sistemas de engenharia, este trabalho apresenta um ambiente de projeto que inclui uma série de inovações que permitem otimizar problemas multidisciplinares utilizando colaboração remota pela Internet. Muitos trabalhos têm sido desenvolvidos nesse sentido, o que motivou uma parceria internacional entre o Departamento de Engenharia Naval da Universidade de São Paulo e a Ecole Centrale de Nantes. O objetivo desta parceria foi unir a experiência brasileira em projetos de sistemas complexos de engenharia com a experiência francesa em otimização multidisciplinar. Sendo este trabalho fruto de uma colaboração internacional, é importante ter em mente a obrigação existente para que a pesquisa desenvolvida atenda a ambas as expectativas. O objetivo é, a um só tempo, viabilizar a integração de subsistemas conhecidos em um ambiente de projeto que permita a otimização multidisciplinar de sistemas complexos de engenharia e desenvolver contribuições pontuais relevantes no uso de superfícies de resposta, projeto distribuído e no desenvolvimento de estratégias de otimização multidisciplinares. O relatório apresentará uma descrição do problema, seguida da revisão bibliográfica sobre os principais assuntos envolvidos na pesquisa. A descrição do trabalho desenvolvido ocupará os dois próximos capítulos. No primeiro, o trabalho é apresentado privilegiando a visão global do sistema e a integração dos diferentes subsistemas desenvolvidos em um enfoque claramente influenciado pela tradicional visão sistêmica da Engenharia Naval. No capítulo seguinte as principais contribuições pontuais desenvolvidas são detalhadas ao estilo Francês. Por fim é apresentada a aplicação deste trabalho em diversos problemas matemáticos e de engenharia. / Facing the modern paradigm of optimized projects of large engineering systems, this research work presents a project environment that includes a series of innovations that allow the optimization of multidisciplinary problems using remote collaboration through the internet. Many research works have been done around this subject, which have motivated an international partnership between the Departamento de Engenharia Naval da Universidade de Sao Paulo and Ecole Centrale de Nantes. The objective of this partnership was mix the Brazilian expertise in design of engineering systems with the French expertise in multidisciplinary optimization. Being the result of an international collaboration, it is important to keep in mind the existing compromise to fulfill both expectations. The objective is altogether to make the integration of known systems viable in a project environment that allows multidisciplinary optimization of complex engineering systems with the creation of focused contributions that are relevant on the use of response surfaces, design collaborative and on the development of strategies of multidisciplinary optimization. The report will present a description of the problem, followed by a bibliographic revision about the main issues involved in the research. The description of the work is covered on the two following chapters. On the first one, the work approaches a global view of the system and the integration of different developed sub-systems under a perspective clearly influenced by the traditional systemic vision of Naval Engineering. On the next chapter, the main punctual contributions are detailed in the French style. Finally, the application of this work is presented in several mathematical and engineering problems.

Composite structures can lower the weight of an airliner significantly. Due to the higher process complexity and the high material cost, however, the low weight often comes with a significant increase in production cost. The application of cost-effective design strategies is one mean to meet this challenge. In this thesis, a simplified form of direct operating cost is suggested as a comparative value that in combination with multidisciplinary optimization enables the evaluation of a design solution in terms of cost and weight. The proposed cost optimization framework takes into account the manufacturing cost, the non-destructive testing cost and the lifetime fuel consumption based on the weight of the aircraft, thus using a simplified version of the direct operating cost as the objective function. The manufacturing cost can be estimated by means of different techniques. For the proposed optimization framework, feature-based parametric cost models prove to be most suitable. Paper A contains a parametric study in which a skin/stringer panel is optimized for a series of cost/weight ratios (weight penalties) and material configurations. The weight penalty (defined as the specific lifetime fuel burn) is dependent on the fuel consumption of the aircraft, the fuel price and the viewpoint of the optimizer. It is concluded that the ideal choice of the design solution is neither low-cost nor low-weight but rather a combination thereof. Paper B proposes the inclusion of non-destructive testing cost in the design process of composite components, and the adjustment of the design strength of each laminate according to inspection parameters. Hence, the scan pitch of the ultrasonic testing is regarded as a variable, representing an index for the guaranteed material quality. It is shown that the cost for non-destructive testing can be lowered if the quality level of the laminate is assigned and adjusted in an early design stage. In Paper C and Paper D the parameters of the manufacturing processes are upgraded during the cost optimization of the component. In Paper C, the framework is extended by the cost-efficient adaptation of parameters in order to reflect the situation when machining an aluminum component. For different weight penalties, the spar thickness and stringer geometry of the provided case study vary. In addition, another cutter is chosen with regard to the modified shape of the stringer. In Paper D, the methodology is extended to the draping of composite fabrics, thus optimizing not only the stacking layup, but also the draping strategy itself. As in the previous cases, the design alters for different settings of the weight penalty. In particular, one can see a distinct change in fiber layup between the minimum weight and the minimum cost solution. Paper E summarizes the work proposed in Papers A-D and provides a case study on a C-spar component. Five material systems are used for this case study and compared in terms of cost and weight. The case study shows the impact of the weight penalty, the material cost and the labor rate on the choice of the material system. For low weight penalties, for example, the aluminum spar is the most cost-effective solution. For high weight penalties, the RTM system is favorable. The paper also discusses shortcomings with the presented methodology and thereby opens up for future method developments. / QC 20100723 / European Framework Program 6, project ALCAS, AIP4-CT-2003-516092 / Nationella flygtekniska forskningsprogrammet (NFFP) 4, project kostnadseffektiv kompositstruktur (KEKS)

Diante do moderno paradigma de projeto otimizado de grandes sistemas de engenharia, este trabalho apresenta um ambiente de projeto que inclui uma série de inovações que permitem otimizar problemas multidisciplinares utilizando colaboração remota pela Internet. Muitos trabalhos têm sido desenvolvidos nesse sentido, o que motivou uma parceria internacional entre o Departamento de Engenharia Naval da Universidade de São Paulo e a Ecole Centrale de Nantes. O objetivo desta parceria foi unir a experiência brasileira em projetos de sistemas complexos de engenharia com a experiência francesa em otimização multidisciplinar. Sendo este trabalho fruto de uma colaboração internacional, é importante ter em mente a obrigação existente para que a pesquisa desenvolvida atenda a ambas as expectativas. O objetivo é, a um só tempo, viabilizar a integração de subsistemas conhecidos em um ambiente de projeto que permita a otimização multidisciplinar de sistemas complexos de engenharia e desenvolver contribuições pontuais relevantes no uso de superfícies de resposta, projeto distribuído e no desenvolvimento de estratégias de otimização multidisciplinares. O relatório apresentará uma descrição do problema, seguida da revisão bibliográfica sobre os principais assuntos envolvidos na pesquisa. A descrição do trabalho desenvolvido ocupará os dois próximos capítulos. No primeiro, o trabalho é apresentado privilegiando a visão global do sistema e a integração dos diferentes subsistemas desenvolvidos em um enfoque claramente influenciado pela tradicional visão sistêmica da Engenharia Naval. No capítulo seguinte as principais contribuições pontuais desenvolvidas são detalhadas ao estilo Francês. Por fim é apresentada a aplicação deste trabalho em diversos problemas matemáticos e de engenharia. / Facing the modern paradigm of optimized projects of large engineering systems, this research work presents a project environment that includes a series of innovations that allow the optimization of multidisciplinary problems using remote collaboration through the internet. Many research works have been done around this subject, which have motivated an international partnership between the Departamento de Engenharia Naval da Universidade de Sao Paulo and Ecole Centrale de Nantes. The objective of this partnership was mix the Brazilian expertise in design of engineering systems with the French expertise in multidisciplinary optimization. Being the result of an international collaboration, it is important to keep in mind the existing compromise to fulfill both expectations. The objective is altogether to make the integration of known systems viable in a project environment that allows multidisciplinary optimization of complex engineering systems with the creation of focused contributions that are relevant on the use of response surfaces, design collaborative and on the development of strategies of multidisciplinary optimization. The report will present a description of the problem, followed by a bibliographic revision about the main issues involved in the research. The description of the work is covered on the two following chapters. On the first one, the work approaches a global view of the system and the integration of different developed sub-systems under a perspective clearly influenced by the traditional systemic vision of Naval Engineering. On the next chapter, the main punctual contributions are detailed in the French style. Finally, the application of this work is presented in several mathematical and engineering problems.

A procedure for generating a customized weight function for wing bending material weight of a High Speed Civil Transport (HSCT) is described. The weight function is based on HSCT configuration parameters. A response surface methodology is used to fit a quadratic polynomial to data gathered from a large number of structural optimizations. To reduce the time of performing a large number of structural optimizations, coarse-grained parallelization with a master-slave processor assignment on an Intel Paragon computer is used. The results of the structural optimization are noisy. Noise reduction in the structural optimization results is discussed. It is shown that the response surface filters out this noise. A statistical design of experiments technique is used to minimize the number of required structural optimizations and to maintain accuracy. Simple analysis techniques are used to find regions of the design space where reasonable HSCT designs could occur, thus customizing the weight function to the design requirements of the HSCT, while the response surface itself is created employing detailed analysis methods. Analysis of variance is used to reduce the number of polynomial terms in the response surface model function. Linear and constant corrections based on a small number of high fidelity results are employed to improve the accuracy of the response surface model. Configuration optimization of the HSCT employing a customized weight function is compared to the configuration optimization of the HSCT with a general weight function. / Ph. D.

Multidisciplinary Design Optimization (MDO) is an area in engineering design which has been growing rapidly in terms of applications in the last few decades, aircraft design being no exception to that. The application of MDO to aircraft and more specifically, wing design, presents many challenges, since disciplines like aerodynamics and structures have to be combined and interact. The level to which this interaction is implemented depends only on how much one is willing to pay in terms of computational cost. The objective of the current work is therefore to develop a simplified MDO tool, suitable for the preliminary design of aircraft wings. At the same time, versatility in the definition of optimization problems (in terms of design variables, constraints and objective function) is given great attention. At the same time, modularity will ensure that this framework is upgradeable with higher-fidelity and/or more capable modules. The disciplines that were chosen for interaction were aerodynamics and structures/ aeroelasticity, though more data can be extracted from their results in order to perform other types of analyses. The aerodynamics module employs a Vortex Lattice code developed specifically for the current implementation of the tool. The structural module is based on Equivalent Plate model theory. The fluid structure interaction is simply one-way, wherein the aerodynamics loads are passed on to the structural analyzer for computation of the static deformation. Semi-empirical relations are then used to estimate the flutter speed. The optimizer, which controls the activity of the other modules, makes use of a gradient based algorithm (Sequential Quadratic Programming) to search for a local minimum of a user defined objective function. Among the myriad of MDO strategies available, two are chosen to exemplify the modularity of the tool developed: Multidiscipline Feasible (MDF) and Sequential Optimization (SO), and their results are compared. Several case studies are analyzed to cover a broad spectrum of the capabilities of the framework. Because user interaction is of prime concern in design optimization, a graphical interface (GUI) of the tool is presented. Its advantages in terms of the set up of optimization problems and post-processing of results are made clear. In conclusion, some topics for future work regarding the expansion and improvement of the features of the application are noted.

The goal of this work was to develop metamodels of the MDO framework piMDO and provide new research in metamodeling strategies. The theory of existing metamodels is presented and implementation details are given. A new trust region scheme --- metamodel trust region optimization (MTRO) --- was developed. This method uses a progressive level of minimum validity in order to reduce the number of sample points required for the optimization process. Higher levels of validity require denser point distributions, but the reducing size of the region during the optimization process mitigates an increase the number of points required. New metamodeling strategies include: inherited optimal latin hypercube sampling, hybrid latin hypercube sampling, and kriging with BFGS. MTRO performs better than traditional trust region methods for single discipline problems and is competitive against other MDO architectures when used with a CSSO algorithm. Advanced metamodeling methods proved to be inefficient in trust region methods.

The goal of this work was to develop metamodels of the MDO framework piMDO and provide new research in metamodeling strategies. The theory of existing metamodels is presented and implementation details are given. A new trust region scheme --- metamodel trust region optimization (MTRO) --- was developed. This method uses a progressive level of minimum validity in order to reduce the number of sample points required for the optimization process. Higher levels of validity require denser point distributions, but the reducing size of the region during the optimization process mitigates an increase the number of points required. New metamodeling strategies include: inherited optimal latin hypercube sampling, hybrid latin hypercube sampling, and kriging with BFGS. MTRO performs better than traditional trust region methods for single discipline problems and is competitive against other MDO architectures when used with a CSSO algorithm. Advanced metamodeling methods proved to be inefficient in trust region methods.

The main objective of this thesis is to introduce the reader to the problematics of air-launch and to a custom design solution applying this concept. The specifics of this method of bringing a payload into orbit are described and explained. Overview of projects which use aircraft to launch spacecraft is included. Determination of primary parameters of a launch vehicle designed to carry a payload of a specified mass is conducted. The required flight performance has been estimated, a computational model has been developed in software MATLAB, and a multidisciplinary optimization of the design parameters has been performed using a genetic algorithm optimization method. Parameters of the designed air-launched rocket are compared with those of a ground-launched rocket. According to the specific criteria, the Airbus A310-300 aircraft was selected as the most suitable transport aircraft to be used for launching the designed launch vehicle. The last part of the thesis is devoted to the proposal of necessary modifications and estimation of the flight performance.

Market globalization and mass customization requirements are forcing companies towards automation of their product development processes. Many task-specific software solutions provide localized automation. Coordinating these local solutions to automate higher-level processes requires significant software maintenance costs due to the incompatibility of the software tools and the dynamic nature of the product development environment. Current automation methods do not provide the required level of flexibility to operate in this dynamic environment. An autonomic product development process automation strategy is proposed in order to provide a flexible, standardized approach to product development process automation and to significantly reduce the software maintenance costs associated with traditional automation methods. Key elements of the strategy include a formal approach to decompose product development processes into services, a method to describe functional and quality attributes of services, a process modeling algorithm to configure processes composed of services, a method to evaluate process utility based on quality metrics and user preferences, and an implementation that allows a user to instantiate the optimal process. Because the framework allows a user to rapidly reconfigure and select optimal processes as new services are introduced or as requirements change, the framework should reduce burdensome software maintenance costs associated with traditional automation methods and provide a more flexible approach.

The structural optimization of a cantilever aircraft wing with curvilinear spars and ribs and stiffeners is described. The design concept of reinforcing the wing structure using curvilinear stiffening members has been explored due to the development of novel manufacturing technologies like electron-beam-free-form-fabrication (EBF3). For the optimization of a complex wing, a common strategy is to divide the optimization procedure into two subsystems: the global wing optimization which optimizes the geometry of spars, ribs and wing skins; and the local panel optimization which optimizes the design variables of local panels bordered by spars and ribs. The stiffeners are placed on the local panels to increase the stiffness and buckling resistance. The panel thickness, size and shape of stiffeners are optimized to minimize the structural weight. The geometry of spars and ribs greatly influences the design of stiffened panels. During the local panel optimization, the stress information is taken from the global model as a displacement boundary condition on the panel edges using the so-called "Global-Local Approach". The aircraft design is characterized by multiple disciplines: structures, aeroelasticity and buckling. Particle swarm optimization is used in the integration of global/local optimization to optimize the SpaRibs. The interaction between the global wing optimization and the local panel optimization is usually computationally expensive. A parallel computing technology has been developed in Python programming to reduce the CPU time. The license cycle-check method and memory self-adjustment method are two approaches that have been applied in the parallel framework in order to optimize the use of the resources by reducing the license and memory limitations and making the code robust. The integrated global-local optimization approach has been applied to subsonic NASA common research model (CRM) wing, which proves the methodology's application scaling with medium fidelity FEM analysis. Both the global wing design variables and local panel design variables are optimized to minimize the wing weight at an acceptable computational cost. The structural weight of the wing has been, therefore, reduced by 40% and the parallel implementation allowed a reduction in the CPU time by 89%. The aforementioned Global-Local Approach is investigated and applied to a composite panel with crack at its center. Because of composite laminates' heterogeneity, an accurate analysis of these requires very high time and storage space. In the presence of structural discontinuities like cracks, delaminations, cutouts etc., the computational complexity increases significantly. A possible alternative to reduce the computational complexity is the global-local analysis which involves an approximate analysis of the whole structure followed by a detailed analysis of a significantly smaller region of interest. We investigate here the performance of the global-local scheme based on the finite element method by comparing it to the traditional finite element method. To do so, we conduct a 2D structural analysis of a composite square plate, with a thin rectangular notch at its center, subjected to a uniform transverse pressure, using the commercial software ABAQUS. We show that the presence of the thin notch affects only the local response of the structure and that the size of the affected area depends on the notch length. We investigate also the effect of the notch shape on the response of the structure. Stiffeners attached to composite panels may significantly increase the overall buckling load of the resultant stiffened structure. Buckling analysis of a composite panel with attached longitudinal stiffeners under compressive loads is performed using Ritz method with trigonometric functions. Results are then compared to those from ABAQUS FEA for different shell elements. The case of composite panel with one, two, and three stiffeners is investigated. The effect of the distance between the stiffeners on the buckling load is also studied. The variation of the buckling load and buckling modes with the stiffeners' height is investigated. It is shown that there is an optimum value of stiffeners' height beyond which the structural response of the stiffened panel is not improved and the buckling load does not increase. Furthermore, there exist different critical values of stiffener's height at which the buckling mode of the structure changes. Next, buckling analysis of a composite panel with two straight stiffeners and a crack at the center is performed. Finally, buckling analysis of a composite panel with curvilinear stiffeners and a crack at the center is also conducted. ABAQUS is used for these two examples and results show that panels with a larger crack have a reduced buckling load. It is shown also that the buckling load decreases slightly when using higher order 2D shell FEM elements. A damage tolerance framework, EBF3PanelOpt, has been developed to design and analyze curvilinearly stiffened panels. The framework is written with the scripting language PYTHON and it interacts with the commercial software MSC. Patran (for geometry and mesh creation), MSC. Nastran (for finite element analysis), and MSC. Marc (for damage tolerance analysis). The crack location is set to the location of the maximum value of the major principal stress while its orientation is set normal to the major principal axis direction. The effective stress intensity factor is calculated using the Virtual Crack Closure Technique and compared to the fracture toughness of the material in order to decide whether the crack will expand or not. The ratio of these two quantities is used as a constraint, along with the buckling factor, Kreisselmeier and Steinhauser criteria, and crippling factor. The EBF3PanelOpt framework is integrated within a two-step Particle Swarm Optimization in order to minimize the weight of the panel while satisfying the aforementioned constraints and using all the shape and thickness parameters as design variables. The result of the PSO is used then as an initial guess for the Gradient Based Optimization using only the thickness parameters as design variables. The GBO is applied using the commercial software VisualDOC. / Ph. D.