The incorporation of inflatable structures into aerospace systems can produce significant advantages in stowed volume to mechanical effectiveness and overall weight. Many applications of these ultra-lightweight systems are designed to precisely control internal or external surfaces, or both, to achieve desired performance. The modeling of these structures becomes complex due to the material nonlinearities inherent to the majority of construction materials used in inflatable structures. Furthermore, accurately modeling the response and behavior of the interfacing boundaries that are common to many inflatable systems will lead to better understanding of the entire class of structures. The research presented involved using nonlinear finite element simulations correlated with photogrammetry testing to develop a procedure for defining material properties for commercially available polyurethane-coated woven nylon fabric, which is representative of coated materials that have been proven materials for use in many inflatable systems. Further, the new material model was used to design and develop an inflatable pathfinder system which employs only internal pressure to control an assembly of internal membranes. This canonical inflatable system will be used for exploration and development of general understanding of efficient design methodology and analysis of future systems. Canonical structures are incorporated into the design of the phased pathfinder system to allow for more universal insight. Nonlinear finite element simulations were performed to evaluate the effect of various boundary conditions, loading configurations, and material orientations on the geometric precision of geometries representing typical internal/external surfaces commonly incorporated into inflatable pathfinder system. The response of the inflatable system to possible damage was also studied using nonlinear finite element simulations. Development of a correlated material model for analysis of the inflatable pathfinder system has improved the efficiency of design and analysis techniques of future inflatable structures.

L'objectif de ce travail est de fournir des modèles et outils pour simplifier la construction des systèmes distribués à base de composants sécurisés, ainsi que la gestion des propriétés de sécurité, en utilisant des outils de haut niveau d'abstraction pour la configuration et la reconfiguration dynamique. En plus des propriétés d'accessibilité et de communications sécurisées classiques, nous focalisons notre travail sur une propriété des systèmes répartis plus générale : la non-interférence. Cette propriété atteste qu'il ne doit pas y avoir de flux d'information entre des parties publiques et privées du système. Ce qui implique le suivi de l'acheminement de l'information entre les différentes composantes du système distribué. Notre objectif principal est donc de proposer un modèle, accompagné d'un ensemble d'outils, garantissant la propriété de la non-interférence à la construction du système, et ce à une plus grosse granularité : celle des composants. Ces outils permettent de (1) configurer les paramètres de sécurité des composants et des liaisons entre eux, (2) vérifier la propriété de non-interférence dans le code d'un composant et entre les différents composants du système et (3) générer automatiquement le code nécessaire pour appliquer ces propriétés de sécurité. D'autre part, nous proposons une architecture permettant de vérifier dynamiquement la propriété de non-interférence dans un système réparti.

Pour demeurer compétitives, de plus en plus d'entreprises sont amenées à collaborer dans le cadre des entreprises étendues ou des réseaux d'entreprises. Ce type d'organisation nécessite l'interconnexion d'une multitude de systèmes d'entreprises, hétérogènes que ce soit par les fonctions qu'ils assurent ou par leurs conceptions (modèles, architectures, ...). Typiquement, ceci renvoie au concept de l'interopérabilité, définie par la capacité des systèmes ou des organisations à fournir ou à accepter des services et à utiliser ces services pour opérer efficacement ensemble. L'échange de l'information et le partage des connaissances (interopérabilité technique) entre les différents systèmes d'information sont désormais des atouts majeurs pour favoriser l'activité collaborative de création de valeur. Le développement de nouvelles technologies et la mise en place de standards a contribué à résoudre (partiellement au moins) ce problème d'interopérabilité technique. Cependant, ce n'est pas suffisant pour garantir l'interopérabilité à un niveau conceptuel : c'est-à-dire garantir que les modèles issus d'une ingénierie peuvent être partagés et compris par rapport à une sémantique commune, et utilisés par les différents systèmes d'entreprise pour réaliser une mission globale. L'approche de gestion du cycle de vie du produit (PLM) est considérée comme une solution essentielle pour faciliter le partage de modèles relatifs à des produits fabriqués. Elle vise à fournir une plate-forme commune qui rassemble les différents systèmes de l'entreprise à chaque étape du cycle de vie du produit dans ou à travers les entreprises. Bien que les principaux éditeurs de logiciels fassent des efforts pour créer des outils offrant un ensemble complet et intégré de modèles, la plupart d'entre eux n'intègrent pas une gestion cohérente des connaissances formalisées dans ces modèles spécifiques à chaque métier. L'hétérogénéité tant syntaxique que sémantique de ces modèles est souvent source d'une interprétation erronée des spécifications produites par chaque environnement de modélisation. L'objectif de cette thèse est ainsi de proposer une méthode, une formalisation et des outils pour prendre en compte, tout au long du cycle de vie d'un produit, l'ensemble des connaissances tacites et explicites sous la forme d'annotations sémantiques formelles qui peuvent favoriser la compréhension partagée ainsi qu'une vérification de cohérence des modèles produits, dans un contexte PLM.

Multiple enterprises are usually involved in supply chain network, while almost each enterprise has its own information systems and databases (enterprise legacy systems). There are large quantities of information and data intersecting or even repeating with each other, which calls for system integration. Meanwhile in the cooperative process of supply chain, the whole product line or product family is involved in the enterprise systems, including PDM, ERP, SCM, and CRM et al, which also need interaction and integration. Although many data integration methods and corresponding tools have been applied to the business cooperation in the environment of supply chain, however the interoperability of enterprise information systems is becoming more and more complex, because of the restriction from lots of factors, such as the complexity of enterprise application systems and the diversity of heterogeneous data sources, especially the new application demands of enterprises. In this dissertation, the interoperability method of networked enterprise information systems in the environment of supply chain is studied, from the point of theoretical modeling and application.

With the rise of automation in traditional manufacturing processes, more companies are beginning to integrate computer integrated manufacturing (CIM) cells on their production floors. Through CIM cell integration, companies have the ability to reduce process time and increase production. One of the problems created with CIM cell automation is caused by the dependency the sequential steps have on one another. Dependency created by the previous step increases the probability that a process error could occur due to previous variation. One way to eliminate this dependency is through the use of an in-process measuring device such as a Renishaw spindle probe used in conjunction with a computer numerical control (CNC) milling machine. Western Kentucky University (WKU) utilizes a CIM cell in the Senator Mitch McConnell Advanced Manufacturing and Robotics laboratory. The laboratory is located in the Architectural and Manufacturing Sciences department and gives students the opportunity to learn how automated systems can be integrated. The CIM cell consists of three Mitsubishi six-axis robots, a Haas Mini-mill, a Haas GT-10 lathe, an AXYZ, Inc. CNC router table, 120 watt laser engraver, an Automated Storage and Retrieval System (ASRS), material handling conveyor, and vision station. The CIM cell functions throughout the curriculum as a means for applied learning and research. The researcher used this CIM cell in order to determine if an in-process measuring device, such as the Renishaw spindle probe, had the ability to affect process capability. The researcher conducted the study to see if an in-process measuring device can be integrated into the CIM cell located in the Senator Mitch McConnell Advanced Manufacturing and Robotics laboratory to eliminate compounding variation. The researcher discovered that through the use of a Renishaw 40-2 spindle probe used in conjunction with a CNC Haas Mini Mill, process capability has the potential to be improved in a CIM cell by accounting for compounding variation present in the process.

Os métodos de geração de malhas são essenciais para simulações numéricas de engenharia. Simulações estruturais pelo método dos elementos finitos (MEF) dependem diretamente das malhas que representam as geometrias às quais são impostos os carregamentos e parte importante da precisão dos cálculos é devida à qualidade da malha. Há uma vasta variedade de métodos e algoritmos para gerar malhas computacionais direcionadas à aplicação do MEF, mas nem todos abrangem geometrias genéricas ou irregulares. Figuras irregulares com regiões curvas e vazios internos requerem o uso de algoritmos específicos, ou genéricos o suficiente, de modo que sejam capazes de processar suas particularidades geométricas, gerando elementos de boa qualidade. Este trabalho propõe uma investigação dos métodos geradores de malhas que tratem as geometrias frequentemente apresentadas nas seções transversais dos componentes dos cabos umbilicais e tubos flexíveis, selecionando criteriosamente aquele que mais se adapte às necessidades geradas pela aplicação do MEF nestas geometrias. Foi realizada uma breve revisão do estado da arte dos métodos geradores de malhas bidimensionais partindo das revisões já publicadas e de artigos explicando versões de algoritmos, seguindo os trabalhos encontrados na literatura. São formulados os critérios de seleção de métodos geradores de malha e de trabalhos encontrados baseando-se nas características. Ao final, o Método de Pavimentação foi selecionado e, a partir de sua implementação computacional, foi desenvolvido o GreenMesh, um programa de computador gerador de malhas utilizando figuras dadas como entrada. Foram geradas várias malhas a partir das geometrias típicas dos equipamentos aqui focados e com isso foi verificado o uso do algoritmo para este fim. / Computational mesh generation methods are essential for engineering numerical simulation. Structural simulations by the finite element method (FEM) rely straightly of meshes that represent the geometries on which the loads are imposed. They are very important for the calculus precision because the mesh quality influences the results. There is a vast variety of computational mesh generation methods and algorithms aimed to FEM analysis, but not all handles generic and irregular geometries. Irregular figures formed by curved regions and internal void requires the use of specific algorithms, or sufficiently generic, in a way that they can process geometric particularities, generating good quality elements. This work proposes an investigation of mesh generation methods that handle frequently presented geometries in cross sections of umbilical cable and flexible pipes internal components, selecting judiciously the method that best suits the necessities generated by the application of FEM analysis on theses geometries. A brief survey about the state of the art of bidimensional mesh generation methods was performed, starting from already published reviews and from articles explaining versions of algorithms, accordingly to the material found in the literature. Finally, the Paving Method has been selected and, starting from its computational implementation, it has been developed GreenMesh, a computer program to generate meshes using given figures as input. It has been generated many meshes from typical geometries of the aimed equipments and that verified the use of the algorithm to this purpose.

Microbubble drag reduction (MBDR) is an effective method to improve the efficiency of fluid systems. MBDR is a field that has been extensively studied in the past, and experimental values of up to 80% to 90% drag reduction have been obtained. The effectiveness and simplicity of MBDR makes it a viable method for real world applications, particularly in naval applications where it can reduce the drag between the surface of ships and the surrounding water. A two dimensional single phase model was created in ANSYS Fluent to effectively model the behavior of bubble laden flow over a flat plate. This model was used to analyze the effectiveness of MBDR based on the following factors: Reynolds number, types of gas injected, upstream flow velocity, upstream fluid type, density ratio, flow rate of injected gas, using air as the upstream injected fluid.

The turbulent nature of the wind flow coupled with additional turbulence created by the wind-building interaction result in highly non-uniform, fluctuating wind-loading on building envelopes. This is true even for simple rectangular symmetric buildings. Building codes and standards should reflect the information on which they are based as closely as possible, and this should be achieved without making the building codes too complicated and/or bulky. However, given the complexity of wind loading on low-rise buildings, its codification can be difficult, and it often entails significant inconsistencies. This required the development of alternative design methods, such as the Database-Assisted-Design (DAD) methodology, that can produce more accurate and risk-consistent estimates of wind loads or their effects. In this dissertation, the DAD methodology for rigid-structures has been further developed into a design tool capable of automatically helping to size member cross sections that closely meet codified strength and serviceability requirements. This was achieved by the integration of the wind engineering and structural engineering phases of designing for wind and gravity loads. Results obtained using this method showed DAD’s potential for practical use in structural design. Different methods of synthesizing aerodynamic and climatological data were investigated, and the effects of internal pressure in structural design were also studied in the context of DAD. This dissertation also addressed the issues of (i) insufficiently comprehensive aerodynamic databases for various types of building shapes, and (ii) the large volume (in size) of existing aerodynamic databases, that can significantly affect the extent to which the DAD methodology is used in engineering practice. This research is part of an initiative to renew the way we evaluate wind loads and perform designs. It is transformative insofar as it enables designs that are safe and economical owing to the risk-consistency inherent in DAD, meaning that enough structural muscle is provided to assure safe behavior, while fat is automatically eliminated in the interest of economy and CO2 footprint reduction.

Hat sections, single and double, made of steel are frequently encountered in automotive body structural components such as front rails, B-Pillar, and rockers of unitized-body cars. These thin-walled components can play a significant role in terms of crashworthiness and impact energy absorption, through a nonlinear phenomenon called as progressive dynamic buckling. As modern vehicle safety design relies heavily on computer-aided engineering, there is a great need for analysis-based predictions to yield close correlation with test results. Although hat sections subjected to axial loading have been studied widely in the past, there is scanty information in published literature on modeling procedures that can lead to robust prediction of test responses. In the current study, both single-hat and double-hat components made of mild steel are studied extensively experimentally and numerically to quantify statistical variations in test responses such as peak load, mean load and energy absorption, and formulate modeling conditions for capturing elasto-plastic material behavior, strain rate sensitivity, spot-welds, etc. that can lead to robust predictions of force-time and force-displacement histories as well as failure modes. In addition, keeping initial stages of vehicle design in mind, the effectiveness of soft computing techniques based on polynomial regression analysis, radial basis functions and artificial neural networks for quick assessment of the behaviors of steel hat sections has been demonstrated. The study is extended to double-hat sections subjected to eccentric impact loading which has not been previously reported. A lightweight enhancement of load carrying capacity of steel hat section components has been investigated with PU (polyurethane) foam-filled single and double hat sections, and subjecting the same to quasi-static and axial impact loading. Good predictions of load-displacement responses are again obtained and shortening of fold lengths vis-à-vis hollow sections is observed. Finally, the performance of hat sections made of glass fiber-reinforced composites is studied as a potential lightweight substitute to steel hat section components. The challenging task of numerical prediction of the behaviors of the composite hat sections has been undertaken using a consistent modeling and analysis procedure described earlier and by choosing an appropriate constitutive behavior available in the popular explicit contact-impact analysis solver, LS-DYNA.

In this study, a non-linear Finite Element (FE) model was created and analyzed to determine the pressure distribution between the residual limb and the prosthetic socket of a transfemoral amputee. This analysis was performed in an attempt to develop a process allowing healthcare providers and engineers to simulate the fit and comfort of transfemoral prosthetics to reduce the number of re-fittings needed for the amputees. The analysis considered the effects of interference due to insertion of the limb into the prosthesis, referred to as donning, and also the effects due to the body weight of the amputee. A non-linear finite element static implicit analysis method was utilized. This analysis implemented multiple finite element techniques, including geometric non-linearity due to large deflections, non-linear contacts due to friction between the contact surfaces of the residual limb and the socket, and non-linear hyper-elastic material properties for the residual limb’s soft tissue. This non-linear static analysis was carried out in two time-steps. The first step involved solving the interference fit analysis to study the pre-stresses developed due to the effect of donning. The donning process results in soft tissue displacement to accommodate the internal geometry of the prosthesis. In the second load application time-step, an additional load of half the person’s body weight was applied to the femur. The maximum normal stress (contact pressure) of 84 kPa was observed due to the combined effect of the donning procedure and body weight application, comparable to the studies performed by other researchers. The procedure developed through this work can be used by future researchers and prosthetic designers in understanding how to better design transfemoral prosthesis.