Thesis (M.Sc. (Hons)) -- University of Western Sydney, Nepean, 2000. / "Thesis submitted for the degree of Master of Engineering (Hons), School of Mechatronic, Computer & Electrical Engineering, University of Western Sydney, Nepean" Bibliography : leaves 129-141.

Thesis (Ph. D.)--Ohio State University, 2008. / Title from first page of PDF file. Includes bibliographical references (p. 172-177).

Mémoire (M.Sc.A.)-- Université du Québec à Chicoutimi, 1992. / Résumé disponible sur Internet. CaQCU Bibliogr.: f. 158-160, 220-221. Document électronique également accessible en format PDF. CaQCU

Thesis (M.S.)--Rochester Institute of Technology, 2009. / Typescript. Includes bibliographical references (leaves 69-72).

Thesis (M.S.)--University of Michigan, 1959.

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains xviii, 178 p.; also includes graphics (some col.) Includes bibliographical references (p. 173-178). Available online via OhioLINK's ETD Center

Na Odontologia, ao se confeccionar peças restauradoras dentárias, pela técnica indireta, o processo mais rotineiramente empregado utiliza um modelo de gesso, obtido a partir de um molde de elastômero, tomado de um dente preparado. Vários fatores podem influenciar na boa precisão de ajustes destas peças como o escoamento do material de vazamento dentro da moldagem, a compatibilidade do material de vazamento com o da moldagem, o tempo de presa, a estabilidade dimensional, a resistência mecânica do material quando da separação moldagem/modelo, a resistência a abrasão e a fidelidade de reprodução de detalhes. Materiais foram introduzidos na odontologia para utilização na confecção de troquéis no intuito de minimizar as desvantagens do gesso, como baixa resistência a abrasão e ligeira expansão de presa. Dentre eles os troquéis metalizados e as resinas epóxicas, que tem vantagens em relação às propriedades mecânicas, porém o primeiro exige técnica demorada e de alto custo e o segundo apresenta contração. O presente trabalho se propõe a testar uma nova composição de poliéster insaturado com estireno adicionado ao carbonato de cálcio em diferentes proporções (10, 20, 30, 40, 50, 60 e 70%) e compará-la ao gesso tipo IV e a resina epoxídica com óxido de alumínio, através de ensaios mecânicos, de abrasão e de alteração dimensional, para avaliar a possibilidade de sua utilização como material de confecção de troquéis para a construção de restaurações indiretas. Para caracterização dos materiais foram feitas análises de espectrometria no infravermelho, Calorimetria de varredura diferencial, termogravimétrica e Microscopia eletrônica de varredura. O compósito a base de poliéster insaturado com 50% de carbonato de cálcio se mostrou viável para utilização como material para troquel. Quando comparado aos materiais de controle mostrou propriedades mecânicas próximas as da resina epoxídica e bem superiores ao gesso, resistência a abrasão superior ao gesso e inferior a resina epoxídica e alteração dimensional próxima a resina epoxídica e maior ao gesso. Sendo a formulação do poliéster/carbonato de cálcio apenas constituída de polímero, catalisador e carga, é possível melhorar a formulação modificando a carga e/ou acrescentando aditivos visando minimizar a contração de polimerização. / In dentistry, the most commonly used procedure to manufacture indirect dental restorations uses a cast of type IV stone. This cast is made from an elastomeric impression of a prepared tooth. Many factors may influence the accuracy of adaptation of these restorations, such as the flow of the pouring material into the mold, the compatibility between the pouring and the impression materials, the setting time, the dimensional stability, the mechanical strength of the material during the mold / cast separation, the abrasion resistance and fidelity to reproduce details. Materials were introduced for preparing dies in order to minimize the disadvantages of the stone, such as its low resistance to abrasion and slight expansion of setting. These materials include metal-plated dies and epoxy resins, which have advantages concerning mechanical properties. However, the first one has a time-consuming technique and requires high costs while the second material shows shrinkage. This study tested a new composition of unsaturated polyester with styrene added to calcium carbonate in different proportions (10, 20, 30, 40, 50, 60 and 70%) and compared it to the type IV stone and to the epoxy resin with aluminum oxide. This comparison was made by mechanical, abrasion and dimensional changes tests in order to evaluate the possibility of using it as material for dies in the process of construction of indirect restorations. The materials were characterized using the analysis of the infrared spectrometry, differential scanning calorimetry, thermogravimetric and scanning electron microscopy. The composite based on unsaturated polyester with 50% calcium carbonate (P5) was considered viable as material for dies. When it was compared to the control materials the following results were found: a) the mechanical properties of P5 are similar to those ones of the epoxy resin and well above the stone ones; b) the abrasion resistance of this new material is lower in relation to the epoxy resin, but higher than the stone one; c) the values for dimensional changes were similar to the epoxy resin ones and superior to those ones found in stone. As the formulation of polyester / calcium carbonate only consists of a polymer, a catalyst and filler particles, it is possible to improve its composition by modifying the filler particles and / or adding additives to minimize the shrinkage of polymerization.

O objetivo no presente trabalho foi avaliar a fidelidade dimensional de troqueis de gesso tipo IV (Vel-Mix®), obtidos a partir de moldes de um único elastômero (Impregum® F), utilizando-se duas diferentes técnicas de moldagem (com casquete ou com moldeira de estoque). A fidelidade de cada troquel obtido foi avaliada através de uma coroa-padrão, a qual encaixava-se com alta precisão ao troquelpadrão, o qual era a estrutura original a ser moldada. Assim foram compostos os 4 seguintes grupos, com o aquecimento do molde não tendo sido efetuado apenas no primeiro deles: 1- do casquete de resina, sem contato com a porção cervical do troquel-padrão (Cstsa); 2- do casquete, também sem o referido contato (Cstca) ; 3- novamente do casquete, agora com contato (Cctca) e 4-. da moldeira de estoque perfurada (Mca). Com base nos resultados encontrados nas condições estabelecidas, após o respectivo tratamento estatístico, foi possível concluir que: 1 - o pior desempenho ocorreu com a moldeira perfurada, com um desajuste médio da ordem de 397, 70 micrometros; 2 - o casquete com toque e com aquecimento (desajuste médio de 85,37 micrometros) apresentou desempenho semelhante ao do casquete sem toque e sem aquecimento (desajuste médio de 102,38 micrometros) e 3 - o melhor desempenho ocorreu com o casquete sem toque e com aquecimento, com um desajuste médio de 0, 03 micrometros. / The aim in this study was to evaluate the dimensional accuracy of dies made with a type IV stone (Vel-Mix®) dies, obtained from moulds of a sole elastomer (Impregum® F), by employing 2 different moulding techniques, with a shell or with a perforated stock tray. Stone dies accuracy was measured by means of a standard crown which could be accurately fitted to the standard die, the original structure to be moulded. In this way, the following 4 groups were stablished, with the mould heating not being done only in the first of them: 1- with the acrylic resin shell cervically not contacting the standard die; 2- with the refered shell but without that contact; 3- once more with the shell, again with that contact and 3- with the stock tray. Under the stablished conditions, after statistical treatment of results, the following conclusions could be drawn: 1- worst performance was presented by the stock tray, with a 397,70 µm mean inaccuracy; 2- the shell performance with cervical contact and heated (85,37 µm mean inaccuracy) was similar to that of it without contact and without heating (102,38 µm mean inaccuracy) and 3- better performance was presented by shell without contact and with heating, with a 0,03 µm mean inaccuracy.

The thesis deals with the design of a single-purpose process tool for the production of sheet metal parts. It contains an analysis of the technologies used by the tool, the calculation of important quantities such as shear clearance, bending radius, suspension and more. The topic also deals with the description of important parts of the tool and their functions.

As part of the development process for new stamping dies, in the automotive sheet metal forming (SMF) industry, the majority of all forming operations are simulated with the Finite Element Method (FEM) before the dies are manufactured. Today, these simulations are conducted with rigid tools under the assumption that there are no tool deformations. However, research shows that tool deformations have an influence on the finished product. In real production these deformations are compensated by manual rework during the try-out. Additional reason for simulating with rigid dies is that there are non-existing simulation methods elaborated for elastic stamping dies. Also, simulation of elastic tools requires high computational power.     Since simulations today are performed with rigid stamping dies the purpose of this work is to investigate the conditions of how to conduct SMF-simulations with elastic stamping dies. The object that will be studied is a stamping die for a Volvo XC90 inner door used in a single-action press. This work is part of the development to minimize the manual rework, with the goal to compensate for tool deformations in a virtual environment.    Results for rigid stamping dies in LS-Dyna was compared to currently used AutoForm as a pre-study. A simple model was then created to find a suitable method while using elastic stamping dies. The developed method was used for an industrial size stamping die.     Since there are little amount of research performed on simulations using elastic stamping dies, elasticity and complexity were gradually introduced into the FE-model. As a first step, only the punch was included as an elastic solid. Secondly, the die was added. Finally, the entire die was simulated as elastic together with the hydraulic cushion of the press. When the FE-model worked as expected a suitable method for minimizing the simulation time with acceptable results was studied.     Comparisons of measured- and simulation results show a high correlation. To improve the results from the FE-model factors such as press deformations, advanced friction models, etc. should be included.    Conclusions from this work shows that it is possible to perform SMF-simulations with elastic stamping dies. As the computational time normally is high this work also presents a method first step to reduce the computational time with acceptable results. Comparisons between simulations with rigid and elastic stamping dies proves that there are significant differences in the outcome of the two methods. / Reduced Lead Time through Advanced Die Structure Analysis - Vinnova