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Origami-based mechanisms have unique characteristics that make them attractive for engineering applications. However, origami-based design is still a developing area of design. Continued work to increase general understanding of key design parameters specific to origami-based mechanisms will increase the ability of designers to capture the potential benefits of origami-based mechanisms. This thesis presents a fundamental study of origami to assist designers in gaining a stronger understanding of the key parameters and capabilities of origami-based mechanisms. As a starting point a study of fundamental motions in action origami models (those that exhibit motions in their folded state) is presented to explore fundamental motions and actuation in origami-based mechanisms. Eleven fundamental motions are outlined and defined with the associated actuation forces that drive them. Additionally, considerations for ensuring necessary performance and force transfer characteristics in origami mechanisms are presented. This is done by exploring the effect of surrogate hinge selections, fold pattern modification, and actuation inputs on the final mechanism. A model of mechanical advantage in origami models consisting of N, degree-4, vertices (where N = 1,2,3,...) is developed and explored. From the exploration of the parameters of the mechanical advantage model it is shown that hinge selection can greatly affect the performance of an origami mechanism by determining its range of motion, precision, and mechanical advantage. Therefore, in order to better understand this important design decision, specific considerations for surrogate hinge selection are presented. These considerations discuss methods to increase performance and reduce hinge imprint, as well as develop surrogate hinges in metals. The key design parameters and considerations presented herein as well as study of origami motions serve to lay the groundwork toward the development of analysis tools and design guidelines specifically suited to origami based design.

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<p>In this thesis I examine the concept of certainty in the work of Ludwig Wittgenstein, with a focus on the collection of remarks entitled <em>On Certainty.</em> In the first part I examine two essays of G.E. Moore that initiated Wittgenstein’s discussion of certainty and critique of Moore’s two essays. As I show, Wittgenstein believes that Moore misunderstood the use of the expression of I know in relation to the propositions of common sense. Instead, Wittgenstein believes that the common sense propositions stand for a certainty that belongs to the language-game itself, a certainty that stands fast for everyone who participates in the language-game, like hinges on which the rest of our knowledge and doubt turn. The rest of my thesis is spent examining three different interpretations of this notion of hinge certainty. The first is hinges as presuppositions to combat skeptical arguments, offered by the philosophers Crispin Wright and H.J. Glock. The second is that hinges are Wittgenstein’s version of foundationalism, serving as the foundational framework of human language, a notion primarily advocated by the philosophers Avrum Stroll and Danièle Moyal-Sharrock. I then examine the interpretation of hinges as learned norms of judging and acting that we must display certainty in if we are to learn a language. This is the interpretation of Rush Rhees and Meredith Williams, and is the position that I support. Finally, I show that contrary to some the remarks in <em>On Certainty </em>express a unified theme, rather than a series of disjointed and contradictory ideas.</p> / Master of Philosophy (MA)

Origami-inspired and deployable technology has become increasingly common in a variety of applications including satellite and antenna designs for space applications. The drive to utilize ultra-thin materials in the design of these deployable space structures has led to the development of membrane hinges. Membrane hinges show promise as an effective surrogate fold because of their potential advantages including requiring minimal volume and mass, allowing for small bending radii, and functioning without lubricant. Two challenges associated with membrane hinges include reliability after repeated cyclic loading and predictability of a large deployable with radially-unconstrained membrane hinges. The research presented includes the cyclic testing and a design analysis of membrane hinges in deployable systems. Additionally, demonstrations of membrane hinges in a variety of applications are included.

Os mecanismos flexíveis são dispositivos capazes de transmitir força e movimento através da deformação elástica. Têm grande importância a uma série de aplicações nas quais os mecanismos de corpos rígidos não seriam viáveis, como por exemplo, os sistemas microeletromecânicos. Existem várias maneiras pelas quais os mecanismos flexíveis podem ser projetados, sendo a otimização topológica um método bastante difundido por ser de aplicação sistemática, ou seja, não requer do projetista qualquer ação analítica durante a etapa de projeto. Na maioria dos casos, o método da otimização topológica combina o método dos elementos finitos com um método de programação matemática. Logo, faz-se necessário discretizar a região do espaço na qual o material disponível será distribuído para determinar o mecanismo flexível adequado à aplicação desejada. Freqüentemente, o mecanismo projetado apresenta duas regiões sólidas unidas por um único nó pertencente à malha de elementos finitos. Durante a transmissão do movimento, este nó age como uma dobradiça conectada às duas regiões. Trata-se de um efeito indesejado, pois compromete a modelagem e a fabricação do componente mecânico. Assim, neste trabalho, foram estudadas técnicas destinadas à redução da ocorrência das \"dobradiças\" no projeto de mecanismos flexíveis por otimização topológica. Foi implementado em linguagem C um código que permite projetar mecanismos flexíveis submetidos a um único carregamento ou múltiplos carregamentos (mecanismos multi-flexíveis). Com o objetivo de analisar e explorar outros aspectos da formulação implementada no código, investigou-se também a sua utilização no projeto de estruturas rígidas. Como resultado, é mostrada a influência dos diversos parâmetros de otimização no projeto de mecanismos flexíveis sem dobradiças, permitindo analisar a eficácia da formulação implementada. / Compliant mechanisms are devices capable of transmitting force and displacement through elastic deformation. They are extremely important for a number of applications in which the mechanisms of rigid bodies would not be feasible, such as microelectromechanical systems. There are several ways through which compliant mechanisms can be designed, being topology optimization a highly diffused method because of its systematic application, once, it does not require from the designer any analytical action during the stage of the project. In most cases, topology optimization method combines the finite element method with a mathematical program method. Therefore, it is necessary to discretize the region of the space in which the available material will be distributed to determine the appropriate compliant mechanism for the desired application. However, the mechanism designed often presents two solid regions united by one single node. During movement transmission, this node acts as a hinge connected to both regions. This is an undesired effect, as it compromises the modeling and manufacturing of the mechanical component. Thus, this work covers techniques aiming at reducing the occurrence of hinges in the design of compliant mechanisms through topology optimization. A code in C language was implemented, which allows the design of compliant mechanisms subjected to one single load or multiple loads (multi-compliant mechanisms). With the purpose of analyzing and exploring other aspects of the formulation implemented in the code, its use in the design of rigid structures was also investigated. As a result, the influence of several optimization parameters in the design of compliant mechanisms without hinges is shown. This allows to analyze the efficiency of the formulation implemented.

Os mecanismos flexíveis são dispositivos capazes de transmitir força e movimento através da deformação elástica. Têm grande importância a uma série de aplicações nas quais os mecanismos de corpos rígidos não seriam viáveis, como por exemplo, os sistemas microeletromecânicos. Existem várias maneiras pelas quais os mecanismos flexíveis podem ser projetados, sendo a otimização topológica um método bastante difundido por ser de aplicação sistemática, ou seja, não requer do projetista qualquer ação analítica durante a etapa de projeto. Na maioria dos casos, o método da otimização topológica combina o método dos elementos finitos com um método de programação matemática. Logo, faz-se necessário discretizar a região do espaço na qual o material disponível será distribuído para determinar o mecanismo flexível adequado à aplicação desejada. Freqüentemente, o mecanismo projetado apresenta duas regiões sólidas unidas por um único nó pertencente à malha de elementos finitos. Durante a transmissão do movimento, este nó age como uma dobradiça conectada às duas regiões. Trata-se de um efeito indesejado, pois compromete a modelagem e a fabricação do componente mecânico. Assim, neste trabalho, foram estudadas técnicas destinadas à redução da ocorrência das \"dobradiças\" no projeto de mecanismos flexíveis por otimização topológica. Foi implementado em linguagem C um código que permite projetar mecanismos flexíveis submetidos a um único carregamento ou múltiplos carregamentos (mecanismos multi-flexíveis). Com o objetivo de analisar e explorar outros aspectos da formulação implementada no código, investigou-se também a sua utilização no projeto de estruturas rígidas. Como resultado, é mostrada a influência dos diversos parâmetros de otimização no projeto de mecanismos flexíveis sem dobradiças, permitindo analisar a eficácia da formulação implementada. / Compliant mechanisms are devices capable of transmitting force and displacement through elastic deformation. They are extremely important for a number of applications in which the mechanisms of rigid bodies would not be feasible, such as microelectromechanical systems. There are several ways through which compliant mechanisms can be designed, being topology optimization a highly diffused method because of its systematic application, once, it does not require from the designer any analytical action during the stage of the project. In most cases, topology optimization method combines the finite element method with a mathematical program method. Therefore, it is necessary to discretize the region of the space in which the available material will be distributed to determine the appropriate compliant mechanism for the desired application. However, the mechanism designed often presents two solid regions united by one single node. During movement transmission, this node acts as a hinge connected to both regions. This is an undesired effect, as it compromises the modeling and manufacturing of the mechanical component. Thus, this work covers techniques aiming at reducing the occurrence of hinges in the design of compliant mechanisms through topology optimization. A code in C language was implemented, which allows the design of compliant mechanisms subjected to one single load or multiple loads (multi-compliant mechanisms). With the purpose of analyzing and exploring other aspects of the formulation implemented in the code, its use in the design of rigid structures was also investigated. As a result, the influence of several optimization parameters in the design of compliant mechanisms without hinges is shown. This allows to analyze the efficiency of the formulation implemented.

Detta projekt gick ut på att undersöka möjligheterna för integrerade gångjärn till köksluckor samt att försöka ta fram en möjlig lösning. Under projektets inledande fas faktainsamlingen undersöktes dagens lösningar, diverse material och tillverkningsmetoder samt tribologi. Kundkrav identifierades som sedan låg till grun-den för funktionsanalysen, dessa funktioner rangordnades. De tre högst prioriterade egenskaperna var dold öppning, monteringsmöjlighet och justeringsmöjlighet. Dessa rangordnade funktionerna användes till idégenereringen och olika koncept togs fram, bland dessa koncept valdes ett som sedan bearbetades i flera iterationer med hjälp av CAD-program och prototyping till ett förfinat koncept som blev projektets resultat. / This project intended purpose was to examine the possibilities with integrated hinges for kitchen cabinet doors and try to develop a plausible solution. The project started with benchmarking and thereafter researching different materials, manufacturing methods and lubricants. Customer demands was also identified and these demands where used for the function analysis. These functions where the backbone of the morphological matrix used in the concept generating process that led to sex different concept ideas, one concept idea was chosen and developed in to one nearly finished product.

Ações sísmicas ocorrem com pouca freqüência e intensidade no Brasil, porém ocorrem em países da América Latina situados na costa do Pacífico e em Portugal, despertando o interesse da engenharia brasileira nesse assunto. Neste trabalho, apresenta-se um modelo numérico para análise de estruturas metálicas aporticadas planas com comportamento elasto-plástico sob excitação aleatória induzida por sismos. Para simular as vibrações aleatórias, utiliza-se uma simulação tipo Monte Carlo fundamentada no ?Vento Sintético?, proposta pelo Prof. Mário Franco. Nessa simulação, combinações de séries de carregamentos harmônicos são geradas com suas amplitudes extraídas de uma Função de Densidade Espectral de Potência (PSDF) das acelerações do solo e com ângulos de fase obtidos por um algoritmo pseudo-aleatório. A PSDF utilizada é um modelo reduzido do modelo Kanai-Tajimi que determina combinações de séries adimensionais, onde seus resultados para o trecho elástico são calibrados com o espectro de resposta elástica sugerido em norma internacional. A integração numérica passo-a-passo no domínio do tempo é feita para cada função de carregamento adotando-se o método de Newmark. O efeito elastoplástico é modelado pelo conceito de rótulas plásticas, assim, a cada passo é verificada a formação da rótula. Se certa seção atingir o momento fletor de plastificação, o valor do momento permanece constante e introduz-se uma rótula nessa seção com rigidez a flexão nula, permitindo rotações finitas livres. Em caso de reversão da direção do momento fletor, a rigidez elástica é integralmente recuperada com a eliminação da rótula do modelo. Ao final desse processo, obtém-se uma grande quantidade de dados de resposta. Faz-se um tratamento estatístico desses resultados de modo a concluir, do ponto de vista da engenharia, a probabilidade de ocorrência dos eventos. Para validar a metodologia proposta, analisou-se um edifício com cinco pavimentos. Os resultados satisfatórios foram obtidos quando comparados com exemplos da literatura, além de apresentarem-se estável com relação a integração no tempo. / Seismic actions occur with low intensity and often in Brazil, however they occur in Latin-American countries on the Pacific Coast and in Portugal, arousing interest in this subject of the Brazilian engineering. In this work, a numerical model is presented for the analysis on the elastic-plastic behavior of steel planar framed structures under random seismic excitation. For random vibrations, a Monte Carlo type simulation is used. This simulation is based on the ?Synthetic Wind?, proposed by Prof. Mario Franco. In this simulation, combinations of series of harmonic loads are generated with their amplitude given by certain provided Power Spectrum Density Functions (PSDF) of ground acceleration and pseudorandomly set phase angles. The used PSDF is reduced model of the Kanai-Tajimi model that determine combinations of non-dimensional series whose results by the behavior elastic are adjusted by international codes Elastic Response Spectra. The step-by-step time integration is performed for each load function using the Newmark method. In order to model, the elastoplastic effect is used the plastic hinge concept. Therefore, at each step the hinge formation is verified. If a certain section reaches its full plastic bending moment, this value of moment is maintained and a hinge in that section is introduced in the model with null stiffness, allowing for free finite rotations. If the rotation in a certain hinged section is reversed, elastic behavior is restored by elimination of the hinge from the model. At the end of this process, a large quantity of response data is obtained. A statistic treatment of these results is performed, in the way that is possible conclude, from the engineering point of view, the probability of occurrence of these events. A statistic treatment based sound engineering conclusions is done for the happened probable events. In order to validate the proposed methodology, a five stories building is analyzed. Satisfactory agreement is obtained when compared to results from the literature, and the results are very stable with respect to the time integration.

Integrally moulded hinges and tension bands are important features in packaging components for plastic closures and their function is critically dependent on the flow induced micromorphology in the hinge section. Polymer characteristics and processing of the hinge also have an influence on the hinge properties obtained. This study is aimed at obtaining interrelationships between polymer characteristics, in-cavity flow, microstructure development and hinge properties, to produce hinges with enhanced functional properties. Three different virgin polypropylene (PP) grades were investigated (homopolymer PP-H, random copolymer PP-RC and impact copolymer PP-IC) and injection moulding simulation was carried out using Moldflow software. In-cavity data acquisition has been carried out for different sets of injection moulding conditions, using high performance transducers and a data acquisition system. A comparison between Moldflow simulation and practical injection moulding data suggests that, for thin wall injection moulded components the real time pressure data are in close agreement during the injection stage. During the packing stage there is some disagreement between these data, since the thickness of hinge and tension band sections are 0.4 mm and 0.5 mm respectively, suggesting that these dimensions are extending the capability of the software. An extensive study using a design of experiments (DoE) approach was carried out on both practical and predictive data. Injection velocity and melt temperature were the most influential factors on the component mechanical properties. From the optical micrographs it is observed that PP-RC has a finer micro-structure compared to PP-H and PP-IC and some micrographs confirm Moldflow simulation results in which hesitation effects are evident, as the flow converges into the thin hinge and tension band sections. PP-clay nanocomposites (PP-CN) were prepared using a twin screw compounder. Transmission electron microscopy (TEM) has shown some evidence of dispersion and exfoliation of the clay particles in the PP matrix. However, X-ray diffraction (XRD) results show a reduction in inter-layer spacing of PPCN s possibly due to clay compaction. The addition of nano-clay however has not resulted in any significant improvements in the mechanical properties of hinges and tension bands. The high degree of molecular orientation induced in the hinge and tension-band sections appears to mask any improvements attributed to the addition of nano-clay. From the reprocessed and post consumer recyclate (PCR) study conducted on hinges and tension bands, it is seen that with an increase in both the re-processing and PCR content there is a decrease in the component strength of around 14%, giving scope to potentially use PCR in future packaging applications. Investigations conducted on colour pigments (violet and green) reveal that the onset of crystallisation for green pigmented mouldings is considerably higher (16°C) than for natural and violet mouldings. Optical micrographs also reveal a finer microstructural texture for green components, indicating a high nucleating capability of the green pigment. Irrespective of the colour, both for hinges and tension bands, the yield stress values were around twice as high as the values quoted in the manufacturer s data sheet for isotropic PP, due to the high levels of molecular orientation in the hinge and tension band sections. In order to industrially validate the findings from the DoE study, commercial closures were produced in industry on a production tool then characterised. In the case of tension bands, there was a good agreement between the results obtained from lab scale and industrial study due to the relatively simple geometry. For hinges this agreement is not so clear. Finally a comparison of mechanical properties of the 3 PP grades shows that PP-H has a higher yield stress compared to PP-IC and PP-RC and yield stress is significantly higher (yield strain values are lower) than values quoted by the manufacturer. The PhD study has confirmed the process conditions that are able to optimise all the interactive effects to improve functional properties in high volume parts in the packaging industry.