No description available.

No description available.

As the field service life of retroreflective raised pavement marker (RRPM) is much shorter than expected, it is necessary to identify the causes and thus improve the RRPM structural design to mitigate the main failure modes, such as poor retention from pavements, structural damage, and loss of retroreflectivity. One strategy for extending RRPM service life is to enhance RRPM geometric characteristics to decrease critical stresses in markers. The main purpose of this thesis is to analyze the relationship between stresses, failure modes, and RRPM profiles. Based on this research, some measures are suggested in order to avoid corresponding failure modes by optimizing RRPM profiles.

The Bogie frame is an important and integral member of bogie. In Indian Railways, LHB (Linke Hofmann Busch) coaches are used as passenger coaches. They are equipped with FIAT bogie frames. Inorder to overcome the limitations of the existing FIAT bogie frame structure, a new bogie frame structure namely New CASNUB Bogie Frame is designed to equip with LHB coach. The New CASNUB Bogie Frame design is validated by conducting Stress analysis using ANSYS Mechanical APDL software. The stresses induced in both the frame structures are compared. Stresses induced in the New CASNUB Bogie frame are lesser than in the FIAT Bogie frame and are within the allowable stress limits of material used. New CASNUB Bogie Frame can be used as an alternative for LHB coaches in Indian Railways.

O estudo comparativo da distribuição de tensões de von Mises em dente endodonticamente tratado, com dois formatos de retentores intra-radiculares, pré-fabricado cilíndrico/escalonado e fundido cônico, foi realizado pelo método dos elementos finitos em modelos tridimensionais de caninos superiores com geometria axi-simétrica e restaurados com coroas metalocerâmicas, aplicando-se uma carga oblíqua de 100N com 45 º de inclinação em relação ao seu longo eixo. Os resultados indicaram uma discreta diferença nos dois modelos (formatos) de retentores. O pino escalonado neutralizou mais as cargas no sentido corono-apical e no pino cônico ficou evidenciado o efeito de cunha. / The aim of this study was to compare the von Mises stress distribution on a human canine teeth endodontically treated and restored with two types of post and core. The analysis was made using the three dimensional Finite Element Analysis method. For the analysis was created and axy-simetric structure of the teeth, including a porcelain fused to metal crown, a cement layer, and the periodontal structures. The model was analyzed when a 100N load was applied on the surface of the crown with 45º angulation with the long axis of the teeth. The results showed that both models exhibit little difference, the “stair shape" post system neutralized the axial loads, and the conical shape post showed a wedge effect on the apical third of the root.

No description available.

Steel Catenary Riser (SCR) is a popular solution for a floating production facility in the deep and ultra-deep ocean. In the analysis of SCR, the behavioral characteristics are investigated to check the failure modes by assessing the magnitude and the frequency of the stress and strain which SCR goes through in time series. SCR is affected by the motions of connected floating production facility and exciting environmental loads. The driven force and motion of SCR has an interaction with seabed soil which represents the stiffness and friction force where SCR touches the seabed. Dynamic response of SCR is primarily caused by the coupled motion of floating structure. The displacement of floating structure is often large and fast enough to cause short cycles of negative and positive tension on SCR. The interaction between SCR and seabed is concentrated at the touchdown zone resulting into the compression and corresponding deformation of pipeline at the position. This paper presents models of floating production facilities and connected mooring lines and SCRs in 100-year hurricane environmental loads and seabed, focusing on the motional characteristics of SCR at the touchdown zone. In time series simulation, the model of SCR is first analyzed as a pipeline with indefinite elasticity so that the SCR does not fail even if the exciting loads exceed the property limit of SCR. Then the SCR design is manually checked using criteria for each failure mode to estimate the integrity.

Submitted by Viviane Lima da Cunha (viviane@biblioteca.ufpb.br) on 2017-07-20T11:05:50Z No. of bitstreams: 1 arquivototal.pdf: 3752282 bytes, checksum: 05ec02c81a4866e4202382045165f792 (MD5) / Made available in DSpace on 2017-07-20T11:05:50Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 3752282 bytes, checksum: 05ec02c81a4866e4202382045165f792 (MD5) Previous issue date: 2015-09-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Pressure drawdown in oil producing fields can lead to reservoir compaction, surface subsidence and cementation/casing failure. The study and understanding of these effects can imply financial and environmental risks reduction. In order to analyze and predict these problems some models were built using the finite element software ABAQUS due to its flexibility in treatment of geometry and topological heterogeneity, use of external routines and plugins. This study describes, through axisymmetric models, the influence of 'depletion' and "coefficient of friction" on reservoir compaction, surface subsidence, von Mises stresses in the casing and slip between cement/casing was analyzed. A central composite rotatable design (CCRD) 22 with four axial points and a center point was made to analyze the significance of the variables through the response surface method. In addition to the quantitative variables, as indicated, it was also analyzed the influence of qualitative variable type of reservoir rock. It was concluded that depletion is a significant variable for the answers "Mises stress", "reservoir compaction" and "subsidence" while the variable coefficient of friction is significant for the answers "Mises stress" and "slip." The type of reservoir rock influences directly the Mises stress, compaction and subsidence. For the same depletion more rigid is the rock, less is the von Mises stress, compaction and subsidence. Also to realize a reduction in the maximum active tension in the coating, for the same level of depletion, friction coefficient and type of reservoir rock when concentric coatings run, due to increased structural capacity. Also was realize, for the same level of depletion, friction coefficient and type of reservoir rock, a reduction in the maximum active stress in the casing, when was used concentric casings, due to increased structural capacity. / Em reservatórios subterrâneos de petróleo, a diminuição da pressão de poros devido à produção pode ocasionar a compactação do reservatório e a consequente subsidência da superfície, além de falhas na cimentação e no revestimento. O estudo e entendimento destes efeitos implicam na redução dos riscos econômicos e ambientais dos projetos de exploração. A fim de analisar e prever estes problemas foram construídos alguns modelos através do simulador de elementos finitos ABAQUS, devido à sua flexibilidade no tratamento da geometria e heterogeneidade topológica, uso de rotinas externas e plugins. Este estudo descreve, através de modelos axissimétricos, a influência das variáveis quantitativas depleção e coeficiente de atrito entre a formação rochosa e a pasta de cimento nas seguintes respostas: compactação do reservatório, subsidência da superfície, estado de tensões de von Mises no revestimento e deslizamento/abertura (falha adesiva) na interface formação rochosa-pasta cimentícia. Com o objetivo de tratar estatisticamente as respostas, foi realizado um delineamento composto central rotacional (DCCR) 22 com quatro pontos axiais e um ponto central, que possibilitou analisar a significância das variáveis através de superfícies de respostas. Além das variáveis quantitativas, já indicadas, foi analisada também a influência da variável qualitativa tipo de rocha reservatório. Concluiu-se que a depleção é uma variável significativa para as respostas tensão de Mises, compactação e subsidência, enquanto a variável coeficiente de atrito é significativa para as respostas tensão de Mises e deslizamento. O tipo de rocha reservatório influencia diretamente nas respostas tensão de Mises, compactação e subsidência. Quanto mais rígida a rocha, menor as tensões atuantes, compactação e subsidência para uma mesma depleção. Percebeu-se, também, uma redução na tensão máxima atuante no revestimento, para um mesmo nível de depleção, coeficiente de atrito e tipo de rocha reservatório, quando são executados revestimentos concêntricos, devido o aumento da capacidade estrutural.

O estudo comparativo da distribuição de tensões de von Mises em dente endodonticamente tratado, com dois formatos de retentores intra-radiculares, pré-fabricado cilíndrico/escalonado e fundido cônico, foi realizado pelo método dos elementos finitos em modelos tridimensionais de caninos superiores com geometria axi-simétrica e restaurados com coroas metalocerâmicas, aplicando-se uma carga oblíqua de 100N com 45 º de inclinação em relação ao seu longo eixo. Os resultados indicaram uma discreta diferença nos dois modelos (formatos) de retentores. O pino escalonado neutralizou mais as cargas no sentido corono-apical e no pino cônico ficou evidenciado o efeito de cunha. / The aim of this study was to compare the von Mises stress distribution on a human canine teeth endodontically treated and restored with two types of post and core. The analysis was made using the three dimensional Finite Element Analysis method. For the analysis was created and axy-simetric structure of the teeth, including a porcelain fused to metal crown, a cement layer, and the periodontal structures. The model was analyzed when a 100N load was applied on the surface of the crown with 45º angulation with the long axis of the teeth. The results showed that both models exhibit little difference, the “stair shape” post system neutralized the axial loads, and the conical shape post showed a wedge effect on the apical third of the root.

Total ankle replacement (TAR) implants are an effective option to restore the range of motion of the ankle joint for arthritic patients. An effective tool for analyzing these implants’ mechanical performance and longevity in-silico is finite element analysis (FEA). ABAQUS FEA was used to statically analyze the von Mises stress and contact pressure on the articulating surface of the bearing component in two newly installed fixed-bearing total ankle replacement implants (the Wright Medical INBONE II and the Exactech Vantage). This bearing component rotates on the talar component to induce primary ankle joint motion of plantarflexion and dorsiflexion. The stress response was analyzed on this bearing component since it is made of the least strong material in the implant assembly (ultra-high molecular weight polyethylene (UHMWPE). This bearing component commonly fails and is the cause for surgeon revisions. Six different FEA models for various gait percentages during stance (10%, 20%, 30%, 40%, 50%, and 60%) were created. They varied in magnitude of the compressive load and the ankle dorsiflexion/plantarflexion angle. This study captured the variation in stress magnitudes based on the portion of the stance phase. The results indicated that the stress distribution on the articulating surface increased as compressive load increased, and the largest magnitudes occurred at high dorsiflexion angles (15-30°). The von Mises stress and contact pressure tended to occur in regions where the thickness of the bearing was the least. Additionally, high contact pressures were examined in areas near the talar component's edge or at the bearing's edges. To the author’s knowledge, this is the first study available to the research community that analyzes the Vantage implant with FEA. This study lays an essential foundation for future researchers in presenting a thorough literature review of TAR and for a simple model setup to capture the stress distributions of two TAR implants. This study provides valuable information that can be beneficial to medical company designers and orthopedic surgeons in understanding the stress response of TAR patients.