Orientador: Luis Roberto Marcondes Martins / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-13T11:40:25Z (GMT). No. of bitstreams: 1 SantosFilho_PauloCesardeFreitas_D.pdf: 10660151 bytes, checksum: bd3f67697b369623400074dcf22ec01c (MD5) Previous issue date: 2009 / Resumo: O objetivo deste estudo foi desenvolver protocolo de modelagem tridimensional para incisivo central superior com aplicabilidade ao método de elementos finitos e avaliar o comportamento biomecânico de incisivo superior tratado endodonticamente e restaurado com retentores e coroa cerâmica por meio de análise por elementos finitos comparado ao dente hígido. Para geração do modelo 3D foi selecionado incisivo central superior hígido. Esmalte e dentina foram degradados em diferentes fases com ácido clorídrico-10%, e mapeados com scanner de contato 3D (Modela, Roland). Para o mapeamento do volume pulpar, a dentina foi seccionada longitudinalmente no sentido mesio-distal e realizado o escaneamento do espaço negativo referente à polpa. Os arquivos *.STL foram exportados para programa Bio-CAD (Rhinoceros-3D). Volumes de cada estrutura dental e técnicas restauradoras foram gerados por meio da associação de superfícies NURBS. Os modelos foram exportados para o programa de elementos finitos (FEMAP-NeiNastran), onde foi realizado o processo de malhagem, inserção das propriedades mecânicas e condições de contorno. Foram gerados 17 modelos, sendo um do dente hígido e 16 modelos de acordo com os 4 fatores em estudo: tipo de retentor em dois níveis: pino de fibra de vidro (PFV) e núcleo moldado fundido (NMF), extensão do retentor em dois níveis: 7,0mm (7,0) e 12,0mm (12,0), remanescente coronário em dois níveis: remanescente de 2,0mm (RE) e ausência de remanescente (ARE), enfraquecimento do canal radicular em dois níveis: ausência de enfraquecimento (AENF) e presença de enfraquecimento (ENF). Foi simulada aplicação de pressão constante no valor de 100N perpendicularmente à superfície palatina do incisivo. Os resultados foram analisados pelo critério de von Mises e tensão máxima principal. Os resultados obtidos mostraram que o modelo geométrico 3D desenvolvido é adequado para a análise por elementos finitos. Concluiu-se que o PFV apresenta distribuição homogênea das tensões mais semelhante ao dente hígido, enquanto o NMF apresentou grande concentração de tensão no interior do canal radicular. O fator extensão do retentor intra-radicular influenciou isoladamente apenas a distribuição de tensões do NMF. A presença de remanescente coronário sempre melhorou a distribuição de tensões. O enfraquecimento do canal radicular teve maior impacto na distribuição de tensões. / Abstract: The aim of this study was develop 3D model generation protocol for upper anterior teeth for finite element analysis and evaluate biomechanical behavior of endodontically treated incisor with finite element analysis compared to sound teeth. It was selected intact upper central incisor. Enamel and dentin were treated in different steps with cloridric acid 2% and scanned with 3D-contact scanner. The stereolithographics archives were exported to Bio CAD program. The volums of each dental structure and restorative techniques were generated by association of NURBS surfaces. The models were exported for finite element software, where were realized the meshed process, mechanical properties insertion and bondary conditions. It were generated 17 models, one was a sound incisor model and 16 models according to 4 studied factors: post type: glass fiber post (GFP) and cast post and core (CPC), post length: 7,0mm (7,0) e 12,0mm (12,0), ferrule: 2,0mm ferrule (FE) and absence of ferrule (AFE), weakness of root canal: absence of weakness (AWR) and weakened root (WR). It was simulated 100N loading application on the palatal surface with 135° angulation. The results were analised by Von Mises criteria and principal maximum tension. Obtained results showed that geometric model developed is appropriated for finite element analysis. It can be concluded that GFP showed homogeneous stress distribution like the sound incisor, while CPC showed stress concentration into root canal. The post length influenced only the CPC stress distribution. The ferrule always showed better stress distribution. The weakness of root showed the highest impact in stress distribution. / Doutorado / Dentística / Doutor em Clínica Odontológica

Orientador: Luís Roberto Marcondes Martins / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-21T16:51:03Z (GMT). No. of bitstreams: 1 Silva_GiseleRodriguesda_D.pdf: 2969310 bytes, checksum: 065fbdffc0e741bd55d3cb562acde2e8 (MD5) Previous issue date: 2012 / Resumo: O objetivo deste estudo foi investigar a influência do retentor intrarradicular, altura do remanescente coronário e tipo de carregamento virtualmente simulado, no comportamento biomecânico de prótese fixa anterior de 3 elementos. Quatro modelos tridimensionais de elementos finitos foram criados comparando-se o tipo de retentor nos dentes pilares (fibra de vidro ou núcleo metálico fundido) e a altura do remanescente coronário (0 e 2 mm). Para simular o tipo de carregamento foram considerados dois níveis de aplicação da força: 1- simulação de contato protrusivo (PRT): 200 N distribuídos nas cristas marginais palatinas dos incisivos superiores, sendo 50 N em cada crista marginal, a 45o do longo eixo do dente e 2- simulação de contato em lateralidade canina (LAT): 200 N aplicados na palatina do canino a 15º. Todos os materiais foram considerados homogêneos, lineares, elásticos e isotrópicos com exceção do pino de fibra de vidro, que foi considerado transversalmente isotrópico. O problema estrutural foi solucionado computacionalmente pelo Método de Elementos Finitos (MEF), em análise estrutural estática. A coerência da simulação foi observada pela análise do deslocamento e pelas tensões de von Mises. O deslocamento foi analisado de forma qualitativa e quantitativa comparando-se a região de deslocamento máximo sofrido pela prótese. Em seguida, foram comparadas as tensões máximas principais ocorridas na região de conexão entre pôntico e dentes pilares, na raiz do incisivo central, do canino e nas interfaces pino-dentina radicular e núcleo de preenchimento-dentina. Concluiu-se que as tensões de tração são concentradas entre pôntico/ pilar e na palatina dos dentes pilares da prótese fixa anterior. Sendo que a protrusão gera maior concentração de tensão máxima principal de tração nos dentes pilares e gera deslocamento duas vezes maior do que a lateralidade. Ademais, a presença de remanescente coronário melhora a distribuição das tensões e o pino de fibra de vidro mostrou-se adequado em prótese fixa anterior de 3 elementos / Abstract: The aim of this study was to investigate the influence of post, load condition and ferule presence in abutment teeth on the stress distribution in the anterior three-unit fixed dental prosthesis (FDP) made of lithium dissilicate. Four three-dimensional finite element (FE) models were created comparing the type of post using on the abutment teeth in two levels (fiberglass post and cast post-and-core) and the coronal remaining in two levels (with or without ferule presence). Two load conditions were applied: 1- 200 N was distributed on palatine marginal ridge of incisive, with 50 N in each ridge, under a 45o angle with the long axis of the tooth, simulating the protrusive contact or 2- 200N was applied on palatine of canine at 15o. All materials were considered homogeneous, linear elastic, and isotropic, with the exception of the glass fiber post, which was considered transversally isotropic. Analysis by Finite Elements Method (FEM), was performed structural analysis. The displacement and Von Mises stress was applied to analyze the coherence o simulation. The displacement was analyzed by quality and quantity resuts in region of maximum prostheses displacement. Maximum principal stress was used as a criterion to compare the study factors. The stress distribution was compared in a descriptive way in the area of the connector, along the interface post/dentin and core/dentin and on abutment dentin teeth. In conclusion, the highest tensile stress was observed in the connector areas and on palatine abutments roots surfaces. The protrusion causes higher stress and displacement than canine guide. The ferrule presence in the abutment teeth reduced the maximum principal tensile stresses on tooth-restoration complex and the fiberglass post seems to improve the stress distribution on anterior 3-unit fixed-dental prostheses / Doutorado / Dentística / Doutora em Clínica Odontológica

En réponse à des contraintes écologiques et économiques de plus en plus forte dans l’industrie, la problématique de réduction et de maîtrise de la consommation énergétique est aujourd’hui prise en considération dans le domaine de la machine-outil. Cette thèse s’inscrit dans le cadre du projet Green HSM porté par l’entreprise PCI-SCEMM ayant pour but de réduire la consommation énergétique d’une machine-outil de 30%. L’étude s’est focalisée sur le thème spécifique de l’allègement de structure. L’objectif est de concevoir des structures de machines-outils avec des masses mobiles les plus faibles possibles tout en gardant une rigidité fonctionnelle.Deux méthodes d’allègement de structures sont proposées dans le cadre de cette thèse. La première présente une méthode d’optimisation de structure de machines-outils par analyse de contraintes. Cette méthode a permis un allègement de deux pièces principales de la structure de 6,5% et 9% pour une réduction globale de la consommation énergétique de 3%.Une autre méthode pour concevoir une structure de machines-outils plus légère utilisant l’optimisation topologique est proposée. La méthode s’appuie sur deux paramètres spécifiques : l’espace de conception et DISCRETE. Cette méthode est présentée dans l’optimisation d’un cas simple de poutre encastrée soumise à un effort de flexion et donne de bons résultats. L’utilisation de la méthode sur le chariot X d’une machine-outil met en évidence les limitations de l’optimisation topologique dans le cas d’étude de structures complexes et l’influence du choix de la solution initiale. / In response to the increase of environmental and economic constraints in industry, the issue of reducing and controlling energy consumption is highlighted in machine tool context. This thesis is part of the Green HSM project carried out by the PCI-SCEMM company with the aim of reducing the energy consumption of a machine tool by 30%. The study focused on the specific topic of lightweight design. The objective is to design machine tool structures with the smallest mass while maintaining functional rigidity.Two methods of lightening structures are proposed in the framework of this thesis. The first one presents a method for optimizing the structure of machine tools by stress analysis. This method allows reducing the mass of two main parts of the structure of 6.5% and 9% for an overall reduction in energy consumption of 3%. Another method for designing a lighter machine structure using topological optimization is proposed. The method is based on two specific parameters: the space design and DISCRETE. This method is presented in the optimization of a simple case of embedded beam subjected to a bending effort and gives good results. The use of the method on the X-axis carriage of a machine tool highlights the limitations of topological optimization in the case of complex structure studies and the influence of the initial solution choice.

This master thesis analyses hook loader NKH 8A340. For calculation of load states was used the dynamic simulation in program MSC.ADAMS. This results were used like a input data to solve the construction with finished element method. After evaluation of results were made design changes of hook loader. Part of this thesis contains drawings of modified parts of hook loader.

Main purpose of the thesis is to carry out a design and a check up of an auxiliary chassis for swap bodies with king pin. The thesis contains pictures of auxiliary chassis made by different producers, followed by my own design. The design contains my own concept of the chassis with purchased parts included. The design of a frame of the auxiliary chassis has been taken in for stress analysis during a number of test loads. Last part of the thesis contains results of stress analysis. Drawings of selected parts are also included. The thesis has been made in cooperation with ZDT Nové Veseli s.r.o.

This thesis deals with the conceptual solution of self-loading container on straw bales. It is the issue of these machines' distribution according to specified criteria at the beginning. Research part follows with describing the individual components cosequently included in the conceptual design. The third point is the design of the solution itself and its rationale. There are itemized individual structural components and visualization. The last part contains strength calculations for structural nodes.

[pt] Apresentam-se as implementações em um programa tridimensional não-linear pelo método dos elementos finitos de análise mecanística de pavimentos flexíveis através do método racional de dimensionamento. Os materiais geotécnicos das diversas camadas que compõem a estrutura do pavimento estão caracterizados através de módulos resilientes, dependentes do estado de tensões atuantes. A influência do carregamento gerado por rodas múltiplas nos campos de tensão e deslocamentos são investigados. Comparações são feitas entre os resultados obtidos nas análises tridimensionais, lineares e não-lineares, com aqueles determinados através de diversos programas computacionais baseados em geral nas hipóteses de axissimetria (carregamento por roda única) e linearidade do meio elástico. Uma aplicação prática é apresentada, considerando-se o pré-dimensionamento de trecho da estrada peruana Iquitos-Nauta. Para determinação de algumas propriedades dos materiais deste pavimento, ensaios específicos foram realizados no Laboratório de Mecânica dos Pavimentos da COPPE/UFRJ. / [en] This work presents the implementation of a non-linear three- dimensional finite element program for the analysis of flexible pavement (highway and runway pavements) through a mechanistic design method. Geotechnical materials of each pavement layer are modeled considering the variable resilient formulation dependent on the actual stress state. The influence of multiple wheel loadings on the displacement and stress fields are also considered and fully investigated. Three-dimensional results of both linear and non-linear analysis are compared with those obtained through several computer programs considering the usual hypotheses of traditional pavement design such as axissymetric loadings (one wheel), linearity of elastic media, etc. An illustrative example is also presented, considering the preliminary design of the Peruvian road between Iquitos-Nauta through the mechanistic method herein introduced. Some of the soil properties related to this application have been determined through specific tests carried out at the COPPE/UFRJ Pavement Laboratory. / [es] Se presentan la implementación del análisis mecánico de pavimentos flexibles a través del método racional de dimensionamento. La implementación fue efectuada a través de un programa tridimensional no lineal por el método de los elementos finitos. Los materiales geotécnicos de los diversos estratos que componen la extructura del pavimento están caracterizados a través de módulos resilientes, dependientes del estado de tensiones actuantes. Se investigan la influencia de la carga generada por ruedas múltiples en los campos de tensión y los desplazamientos, comparando los resultados obtenidos en el análisis tridimensional, lineal y no lineal, con los determinados a través de diversos programas computacionales basados en en las hipóteses de axisimetría (carga por rueda única) y linealidad del medio elástico. Se presenta una aplicación práctica, considerando el predimensionamento de un trecho de la carretera peruana Iquitos-Nauta. Para la determinación de algunas propriedades de los materiales de este pavimento, se realizaron ensayos específicos en el Laboratorio de Mecánica de los Pavimentos de la COPPE/UFRJ.

L'objectif de la thèse est d'analyser le comportement mécanique de matériaux granulaires composites bidimensionels en terme de textures granulaires en utilisant deux approches : étude expérimentale par "thermoelastic stress analysis" et étude numérique par dynamique moléculaire. Les systèmes granulaires composites sont préparés à l'aide de cylindres en polyoxyméthylène (POM) et polyéthylène haute densité (PEHD), présentant un rapport de rigidité de 4 entre eux. Différents rapports de diamètres et de nombres de particules sont considérés. Les résultats expérimentaux et numériques sont en bon accord à l'échelle macroscopique. En particulier, le réseau fort (qui est ici caractérisé par des contraintes hydrostatiques supérieures à la valeur moyenne) contient moins de 50% des particules, et présente une distribution décroissance exponentielle quel que soit le type de particules considéré pour l'analyse (particules souples, particules rigides, toutes les particules). De plus, la distribution des contacts entre particules rigides (contacts POM-POM) est anisotrope et tend à s'organiser dans le sens de la direction du chargement extérieur appliqué, tandis que les autres types de contact agissent principalement pour maintenir le système en équilibre. / The main objective of our dissertation is to analyze the mechanical behavior of two-dimensional composite granular materials through the granular textures. Thermoelatic stress analysis experiments and molecular dynamics simulations are used for this purpose. The composite granular systems are prepared from polyoxymethylene (POM) and high-density polyethylene (HDPE) cylinders with a stiffness ratio of about 4 between them. Different configurations in terms of ratios of diameter size and ratio of particle numbers are systematically investigated. Experimental and numerical results are good correlated at the macroscopic scale. In particular the strong network, which is here characterized by hydrostatic stresses higher than the mean value, consists of less than 50% of all particles, and exhibits an exponential decay whatever the type of particles considered for the analysis (soft, stiff, or both types). In addition, the contact distributions between stiff particles (POM-POM contacts) is anisotropic with an effort to arrange parallel to the direction of the external applied load, whereas the other types of contacts just act to sustain the granular system in equilibrium.

La thermographie infrarouge est un moyen d'analyse du comportement mécanique des matériaux. Elle a connu un essor considérable depuis les années 80 avec l'apparition des premiers capteurs. Deux techniques principales ont pu être développées ; la calorimétrie quantitative et l'analyse des contraintes par thermoélasticité (TSA en anglais). Jusqu'à aujourd'hui, la majorité des travaux a été réalisée sur les métaux et les polymères. Le présent manuscrit relève le challenge d'appliquer ces techniques aux matériaux verres, en développant une méthodologie de débruitage des films thermiques, permettant de conserver la résolution spatiale des mesures thermiques. Cela permet de caractériser de forts gradients dans des champs de variations de température de faible intensité. Cette méthodologie a été utilisée pour débruiter des films thermiques d'échantillons de verre soumis à un chargement mécanique cyclique. Dans un premier temps, elle a été appliquée pour étudier la réponse thermique d'une empreinte à l'échelle microscopique. Dans un second temps, elle a été utilisée pour remonter à des champs de contraintes et de sources de chaleur à l'échelle macroscopique. Ce travail ouvre de nouvelles perspectives à l'étude du comportement thermomécanique des matériaux fragiles présentant une faible réponse thermique sous sollicitation mécanique et de forts effets de gradients spatiaux. Les applications visées sont la fissuration et l'identification de paramètres constitutifs. / The infrared thermography is used to analyse the mechanical behavior of materials. Since the 80's, it has rised with the appearance of the first sensors. Two principal techniques has been developed; the quantitative calorimetry and the thermoelastic stress analysis (TSA). Until today, most of the works has been carried out on metals and polymers. This manuscript takes-up the challenge of applying these techniques to glassy materials by developing a methodology to denoise infrared movies, which allows to preserve the spatial resolution of the thermal measurement. It allows to caracterise high gradients of low temperature variation fields. This methodology has been used to denoised thermal movies of glass samples submitted to a cyclic mechanical test. In a first time, it has been applied to study the thermal response of an imprint at the microscopic scale. In a second time, stress and heat sources fields have been determined at the macroscopic scale. This work provides new possibilities to study the thermomechanical behavior of brittle materials which present a low thermal response and high spatial gradients under mechanical loading. The target applications are the cracking phenomenom and the identification of constitutive parameters.

In aerospace applications, use of laminates made of composite materials as face sheets in sandwich panels are on the rise. These composite laminates have low transverse shear and transverse normal moduli compared to the in-plane moduli. It is also seen that the corresponding transverse strength values are very low compared to the in-plane strength leading to delaminations. Further, in sandwich structures, the core is subjected to significant transverse shear stresses. Therefore the interlaminar stresses (i.e., transverse shear and normal) can govern the design of sandwich structures. As a consequence, the first step in achieving efficient designs is to develop the ability to reliably estimate interlaminar stresses. Stress analysis of the composite sandwich structures can be carried out using 3-D finite elements for each layer. Owing to the enormous computational time and resource requirements for such a model, this process of analysis is rendered inefficient. On the other hand, existing plate/shell finite elements, when appropriately chosen, can help quickly predict the 2-D displacements with reasonable accuracy. However, their ability to calculate the thickness-wise distributions of interlaminar shear and normal stresses and 3-D displacements remains as a research goal. Frequently, incremental refinements are offered over existing solutions. In this scenario, an asymptotically correct dimensional reduction from 3-D to 2-D, if possible, would serve to benchmark any ongoing research. The employment of a mathematical technique called the Variational Asymptotic Method (VAM) ensures the asymptotical correctness for this purpose. In plates and sandwich structures, it is typically possible to identify (purely from the defined material distributions and geometry) certain parameters as small compared to others. These characteristics are invoked by VAM to derive an asymptotically correct theory. Hence, the 3-D problem of plates is automatically decomposed into two separate problems (namely 1-D+2-D), which then exchange relevant information between each other in both ways. The through-the-thickness analysis of the plate, which is a 1-D analysis, provides asymptotic closed form solutions for the 2-D stiffness as well as the recovery relations (3-D warping field and displacements in terms of standard plate variables). This is followed by a 2-D plate analysis using the results of the 1-D analysis. Finally, the recovery relations regenerate all the required 3-D results. Thus, this method of developing reduced models involves neither ad hoc kinematic assumptions nor any need for shear correction factors as post-processing or curve-fitting measures. The results are most general and can be made as accurate as desired, while the procedure is computationally efficient. In the present work, an asymptotically correct plate theory is formulated for composite sandwich structures. In developing this theory, in addition to the small parameters (such as small strains, small thickness-to-wavelength ratios etc.,) pertaining to the general plate theory, additional small parameters characterizing (and specific to) sandwich structures (viz., smallness of the thickness of facial layers com-pared to that of the core and smallness of elastic material stiffness of the core in relation to that of the facesheets) are used in the formulation. The present approach also satisfies the interlaminar displacement continuity and transverse equilibrium requirements as demanded by the exact 3-D formulation. Based on the derived theory, numerical codes are developed in-house. The results are obtained for a typical sandwich panel subjected to mechanical loading. The 3-D displacements, inter-laminar normal and shear stress distributions are obtained. The results are compared with 3-D elasticity solutions as well as with the results obtained using 3-D finite elements in MSC NASTRAN®. The results show good agreement in spite of the major reduction in computational effort. The formulation is then extended for thermo-elastic deformations of a sandwich panel. This thesis is organized chronologically in terms of the objectives accomplished during the current research. The thesis is organized into six chapters. A brief organization of the thesis is presented below. Chapter-1 briefly reviews the motivation for the stress analysis of sandwich structures with composite facesheets. It provides a literature survey on the stress analysis of composite laminates and sandwich plate structures. The drawbacks of the existing anlaytical approaches as opposed to that of the VAM are brought out. Finally, it concludes by listing the main contributions of this research. Chapter-2 is dedicated to an overview of the 3-D elasticity formulation of composite sandwich structures. It starts with the 3-D description of a material point on a structural plate in the undeformed and deformed configurations. Further, the development of the associated 3-D strain field is also described. It ends with the formulation of the potential energy of the sandwich plate structure. Chapter-3 develops the asymptotically correct theory for composite sandwich plate structure. The mathematical description of VAM and the procedure involved in developing the dimensionally reduciable structural models from 3-D elasticity functional is first described. The 1-D through-the-thickness analysis procedure followed in developing the 2-D plate model of the composite sandwich structure is then presented. Finally, the recovery relations (which are one of the important results from 1-D through-the-thickness analysis) to extract 3-D responses of the structure are obtained. The developed formulation is applied to various problems listed in chapter 4. The first section of this chapter presents the validation study of the present formulation with available 3-D elasticity solutions. Here, composite sandwich plates for various length to depth ratios are correlated with available 3-D elasticity solutions as given in [23]. Lastly, the distributions of 3-D strains, stresses and displacements along the thickness for various loadings of a typical sandwich plate structure are correlated with corresponding solutions using well established 3-D finite elements of MSC NASTRAN® commerical FE software. The developed and validated formulation of composite sandwich structure for mechanical loading is extended for thermo-elastic deformations. The first sections of this chapter describes the seamless inclusion of thermo-elastic strains into the 3-D elasticity formulation. This is followed by the 1-D through-the-thickness analysis in developing the 2-D plate model. Finally, it concludes with the validation of the present formulation for a very general thermal loading (having variation in all the three co-ordinate axes) by correlating the results from the present theory with that of the corresponding solutions of 3-D finite elements of MSC NASTRAN® FE commercial software. Chapter-6 summarises the conclusions of this thesis and recommendations for future work.