To see the other types of publications on this topic, follow the link: Rod Fracture.
Dissertations / Theses on the topic 'Rod Fracture'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 27 dissertations / theses for your research on the topic 'Rod Fracture.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Morris, Mark Ian. "Deformation and flow of highly concentrated rod systems." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.279750.
Full text
2
Nickoletopoulos, Nicholas. "Physical and numerical modeling of steel wire rod fracture during upsetting for cold heading operations." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=37796.
Full textAbstract:
A comprehensive methodology to physically and numerically model upsetting in cold heading was developed.The physical model was a Drop Weight Test with a guided pocket-die set capable of approximating industrial cold heading conditions. The results show that the test is sensitive to the critical parameters for cold heading. These include surface quality, residual element level, nitrogen content, microstructure, decarburization, and specimen geometry. The test is capable of assessing the fracture behavior of cold heading materials.
One goal of the study was to reveal differences in fracture behavior with varying steel sources. Accordingly, the matrix of test materials consisted of grade 1038 steels from three different steel sources.
Material preparation and conditioning of test materials approximated industrial procedures for cold heading materials. These procedures included hot rolling, controlled rod cooling, descaling, straightening, lime coating and lubricating, and wire drawing. Spheroidization of test specimens was performed in an industrial batch furnace using an industrial heat treatment cycle.
A finite element program (FEM) enabled the simulation of upsetting in cold heading. The inputs required to model the cold heading process include flow stress behavior and friction conditions representative of cold heading. These inputs were obtained using the CANMET Cam Plastometer and the Friction Ring Test.
The Cockcroft and Latham fracture constants for an as-rolled and a spheroidize annealed 1038 material were computed by FEM modeling and the critical values were calibrated using the Drop Weight Test. The fracture criterion constant was found to be independent of strain path for upsetting in cold heading and thus is material-related.
3
Seyed, Vosoughi Ardalan. "Mitigating the Biomechanical Complications Following Pedicle Subtraction Osteotomy: A Finite Element Analysis." University of Toledo / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1503598742789914.
Full text
4
ALY, OMAR F. "Modelagem da fratura por corrosão sob tensão nos bocais do mecânismo de acionamento das barras de controle de reator de água pressurizada." reponame:Repositório Institucional do IPEN, 2006. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11418.
Full textAbstract:
Made available in DSpace on 2014-10-09T12:51:41Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:10:25Z (GMT). No. of bitstreams: 0
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
5
Hand, R. J. "Impact and fracture properties of infra-red and optical transmitting materials." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233087.
Full textAbstract:
The liquid impact properties of a range of infra-red and optical transmitting materials have been investigated using the liquid jet impact technique. In particular the effects of temperature and pre-existing stress fields on the liquid impact performance of certain materials have been examined. Consideration of these aspects of liquid impact has been supplemented by measurements of related fracture properties. The correlation between liquid jet impact and liquid drop impact has been re-examined for normal impact by comparing impacts on perspex. This correlation has been extended to consider angled impact. Components that are subjected to liquid impact may simultaneously be subjected to elevated temperatures. A system has been developed to allow experimental investigation of the liquid impact performance of materials at elevated temperatures. Preliminary results were obtained on a polymer (PEEK). The amount of damage resulting from liquid impact increased with temperature. Subsequently two brittle materials (glass and zinc sulphide) were investigated. Thermal shock has been shown to be the dominant failure mechanism for these materials at temperatures of 300oC and greater. Pre-existing stresses in a material can affect not only its static but also its dynamic loading response. The liquid impact performance and some associated fracture properties of toughened glass systems have been investigated. Chemically and thermally toughened systems were compared. There is a small increase in the threshold velocity for the toughened glasses considered compared to soda-lime glass. The toughening stresses distributions led to differences in the behaviour under single and multiple impact. A novel computer simulation of liquid impact onto pre-stressed substrates has been developed. It is based on the interaction of a model Rayleigh surface wave with a flaw distribution. Good agreement with experiment was obtained for a thermal toughening stress distribution.
6
Scott, Jeff E. "Vibratory insertion and extraction of surgical implants." Online access for everyone, 2006. http://www.dissertations.wsu.edu/Thesis/Fall2006/j_scott_120406.pdf.
Full text
7
Leszczynski, Aleksander. "Modélisation de l'arthrodèse thoraco-lombaire avec fixation pelvienne dans les déformations du rachis." Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAD041.
Full textAbstract:
La scoliose dégénérative et le déséquilibre antérieur sont des problèmes courants chez les personnes âgées. Afin d'améliorer la qualité de vie, il est conseillé à certains patients de subir une correction chirurgicale. La correction chirurgicale de l'équilibre sagittal entraîne diverses complications, parmi lesquelles les ruptures de tiges qui jouent un rôle central, surtout à long terme. Des études de suivi de patients ont montré qu’une rupture du matériel d’ostéosynthèse est observée chez environ 20% d’entre eux. Le cœur de ce travail de thèse a consisté à développer un modèle éléments finis (MEF) complet du rachis sain. La géométrie utilisée pour la création du MEF a été définie à partir de coupes scanner d’un sujet sain de 47 ans. Des propriétés mécaniques issues d’une large revue bibliographique ont été implémentées aux différentes structures. Afin de vérifier la réponse du MEF ainsi développé, deux types de validation ont été réalisées, en termes d’amplitude de mouvement (ROM), ainsi qu’en termes de fréquences propres et déformées modales correspondantes. Pour l’étude du matériel d’ostéosynthèse, quatre configurations d’instrumentations du MEF ont alors été proposées. Nous avons présenté, pour la première fois, la validation d’un MEF d’une colonne flexible instrumentée en termes de ROM, ainsi que en termes des déformations des tiges principales. En outre, d'autres paramètres mécaniques tels que le champ de pression au niveau des disques/cages, de forces dans les têtes des vis et de la distribution des contraintes de type Von Mises dans les tiges principales ont été évalués. Les études des MEF lombaire instrumentés dans les quatre modes de sollicitations (flexion d'extension, inflexion latérale et torsion), a permis de démontrer que le maximum de contrainte de Von Mises (situé dans les tiges principales) est corrélé avec la zone où se produisent la majorité des fractures. La configuration bilatérale à double tiges avec cages intersomatiques permet néanmoins de réduire au mieux les contraintes de Von Mises calculées/exercées sur les fixateurs rachidiens ce qui présente un risque minimal de rupture de tiges. Une étude complémentaire à également été menée consistant à étudier le MEF d’une colonne vertébrale instrumentée de T10 jusqu’au bassin. Nous avons constaté, que lors d’une instrumentation de la partie thoraco-lombaire, les résultats obtenus numériquement étaient plus critique que lors d’une instrumentation de la partie lombaire seule, notamment en termes de contraintes maximales calculées dans les tiges. Le MEF du rachis développé dans le cadre de ce travail de thèse est véritable outil pouvant être désormais utilisé, afin d’évaluer d’autres techniques d’instrumentation chirurgicale par la méthode des éléments finisDegenerative scoliosis and sagittal imbalance are common problems in the older population. In order to improve the quality of life, some patients are recommended to undergo surgical correction. Surgical correction of the sagittal balance can lead to various complications, including rod fractures, which play a central role in the long term. Patient follow-up studies have shown that a rupture of the osteosynthesis material is observed in about 20% of patients. The main focus of the curent work was the development of a complete finite element model (FEM) of the healthy spine. The geometry of the FEM was based on a CT-scan of a healthy 47-year-old volunteer. Mechanical properties were taken from a wide literature review and implemented. In order to ensure the biofidelity, the spinal FEM was widely validated in terms of range of motion (ROM) and modal analysis against multiple experimental studies from the literature. For the study of osteosynthesis material, four instrumented FEMs of the lumbar spine with different configurations were proposed. For the first time, a validation was performed on instrumented flexible spine FEMs against ROM as well as strains in the main rods. In addition, other mechanical parameters such as intradiscale pressure, forces in the screw heads and the distribution of Von Mises stresses in the main rods were calculated to evaluate the studied instrumented configurations. Outcome of the present study of the four instrumented lumbar FEMs in four loading modes (extension flexion, lateral inflection and torsion) indicated that the maximum Von Mises stress (located in the main rods) is correlated with the area of rod fractures reported in patient follow up studies. However, the bi-lateral double rod configuration with interbody cages produced the higher Von Mises stress reduction on spinal fixators which represents a minimal risk of rod failure. A complementary study was also carried out to investigate the FEM of an instrumented spine from T10 to the pelvis. The results showed that an extension of the instrumentation thoracic part, the numerically obtained values were more critical than during an instrumentation of the lumbar part alone, especially in terms of maximum stresses calculated in the principal rods. The developed spinal FEM can be an effective and efficient tool to evaluate other surgical instrumentation techniques using the finite element method
8
Aniruth, Sunildutt. "Maxillofacial fractures in children attending the Red Cross War Memorial Children's Hospital." Thesis, University of the Western Cape, 2005. http://etd.uwc.ac.za/index.php?module=etd&.
Full textAbstract:
The literature shows that maxillofacial fractures in children are uncommon. Although the Department of Oral and Maxillofacial Surgery of the Faculty of Dentistry, of the University of the Western Cape, has been providing a service to the Red Cross Children&rsquos Hospital (RXH) for the past twenty years, no study had been undertaken to determine the age, gender, number of patients per year, aetiology, patterns, and management of maxillofacial fractures at this institution. A retrospective records based study was undertaken to determine these features. This study accessed the records of patients seen at the trauma unit at RXH, from 1994 to 2003 inclusive, and referred for maxillofacial attention.
One-hundred-and-five patient records were obtained and analyzed using the SPSS statistic package. One-hundred-and-twenty-seven fractures were recorded in one hundred and five patients. The age of the patients ranged from one to thirteen. Sixty-five male and forty female patients were seen. Dentoalveolar fractures were the most common fracture seen in both the midface and mandible. Midface fractures were more common than mandibular fractures. Falls, followed by motor vehicle accidents, were the most common cause of facial fractures. Most fractures were successfully managed by closed procedures. At this institution, nasal and frontal fractures have surprisingly little or no input from the Department of Oral and Maxillofacial Surgery.
9
LOUBET, JEAN-GUY. "Luxation traumatique de hanche et avulsion fracture du ligament rond chez l'enfant : a propos de deux observations." Toulouse 3, 1990. http://www.theses.fr/1990TOU31120.
Full text
10
Felfel, Reda. "Manufacture and characterisation of bioresorbable fibre reinforced composite rods and screws for bone fracture fixation applications." Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/14379/.
Full textAbstract:
Bioresorbable implants are an attractive alternative to metallic bone fixation devices and offer potential to eliminate some of the clinical challenges with the latter. This work explores the manufacturing of fully bioresorbable fibre-reinforced composite rods and screws for such applications. Poly lactic acid (PLA) and phosphate glass fibres (PGF) were combined to provide mechanical reinforcement and biocompatibility characteristics. Aligned and randomly reinforced PLA/PGF composites were prepared by compression moulding prior to thermomechanical deformation into rod and screw forms. In vitro degradation and mechanical properties retention were investigated in phosphate buffered saline (PBS) at 37°C. The composite rods and screws exceeded published data for bioresorbable implants in their virgin state and were towards the upper range of cortical bone properties. The properties reduced rapidly in an aqueous medium and this was attributed to matrix plasticisation and fibre/matrix disbonding. The degraded samples maintained strength and stiffness close to the lower limits of the cortical bone. Water uptake and mass loss for composites exceeded equivalent values for PLA alone due to water wicking at the fibre/matrix interface. Ion release tests correlated linearly with mass loss profiles confirming that the dominant degradation mechanism was fibre dissolution. The PLA/PGF composites also exhibited good biocompatibility to human osteosarcoma and human mesenchymal stem cells.
11
Heisser, Ronald Henry. "Design, development, and characterization of an experimental device to test torsion-controlled fracture of thin brittle rods." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/105705.
Full textAbstract:
Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (page 40).
As research continues to uncover the many different physical properties of meso- and microscale materials, it becomes more evident that these materials often behave in counterintuitive ways. Characterizing unique phenomena not only provides analogies in nature which inspire innovation at all levels of research and design but also presents new possibilities for future technological development. The discussion presented herein explores the design and development of a low-cost, manual device intended to test a hypothesis rooted in the behavior of breaking pasta that intrigued even Richard Feynman. While the mechanism for why spaghetti breaks into three or more pieces has been described, the experimental discussion presented here focuses on the effect that added torsion has on the fracture bent spaghetti. Specifically, it is possible that twisting the spaghetti a critical angle and bending it will cause it to fracture into only one piece. The idea of torsion being used to exhibit some control over how a material fractures has not been well-investigated; the results which come from this experiment may prove useful for applications even beyond the scope of thin brittle materials. With this said, the sensitivity in quantifying breaking from torsion and bending together requires that the experimental device prevent systematic error stress from negatively impacting the accuracy of the experiment. Thus much time is devoted to explanation and rationale behind the analysis of the experimental device. Alongside the device's characterization this thesis serves to be a reflection of the design process taken while creating this device. Lessons learned from this project are included in all aspects of the discussion and a section in the Appendix is devoted to a more detailed account of the design and fabrication of one device component.
by Ronald Henry Heisser.
S.B.
12
Geary, Elizabeth A. "The fatigue and fracture behaviour of quenched and tempered medium to high carbon steels for road breaker applications." Thesis, University of Nottingham, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334975.
Full text
13
Sterckx, Arnaud. "Étude des facteurs influençant le rendement des puits d'alimentation de particuliers qui exploitent le roc fracturé en Outaouais, Québec, Canada." Thesis, Université Laval, 2013. http://www.theses.ulaval.ca/2013/30313/30313.pdf.
Full textAbstract:
La région de l’Outaouais (13760 km²), au Québec, connait une forte croissance démographique et les eaux souterraines sont davantage sollicitées. La perméabilité du socle rocheux, essentiellement cristallin, est contrôlée par des fractures entrecroisées et donc hétérogène. Pour identifier des zones-cibles de forage, nous avons confronté des données de capacité spécifique du Système d’Information Hydrogéologique du Québec, validés à l’aide d’essais de pompage réalisés par l’Université Laval, avec des caractéristiques du roc, parmi lesquelles la lithologie, l’épaisseur de roc exploitée par les puits et la présence de linéaments. Il apparait que la texture et la minéralogie des roches ont une influence sur le développement de fractures perméables. On constate aussi que ces fractures se raréfient en profondeur et qu’il n’est donc pas toujours opportun de forer des puits à des profondeurs importantes (< 80 m). En revanche, aucune corrélation entre la présence de linéaments et le rendement des captage situés à proximité n’a pu être observée.The Outaouais Region (13760 km²) is one of the most rapidly growing communities in Quebec, and where groundwater is increasingly being relied upon as a water supply. The permeability of the mostly crystalline bedrock is controlled by interconnected fractures and then heterogeneous. In order to identify target areas for installing new pumping wells, specific capacity data from the SIH database, which were validated using pumping tests carried out by Université Laval, were compared with rock characteristics including lithology, thickness of rock exploited by each well and proximity to lineaments. The texture and mineralogy of the rock seemed to have an important influence on the development of permeable fractures. We also found that the fracture density decreases with depth and therefore it is not always profitable to drill to deeper depths (> 80 m) to try to increase productivity. In contrast, proximity to lineaments didn’t seem to have any impact on the productivity of wells.
14
Figueiredo, Adriana Valente de. "Estudo biomecânico ex vivo em coluna tóraco-lombar de cães com técnicas de estabilização utilizando Placa Bloqueada, Clamp Rod Internal Fixation, Pino com Cimento Ósseo e Técnica Segmentar Modificada." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/10/10137/tde-20082014-145759/.
Full textAbstract:
Fraturas e luxações vertebrais decorrente de trauma consistem afecção neurológica frequente na prática clínica veterinária, sendo a coluna tóraco-lombar a mais comumente afetada em cães, e em muitos casos o tratamento cirúrgico é de eleição. Existem diversas técnicas propostas a realizar estabilização vertebral, entretanto, estudos em coluna tóraco-lombar não foram realizados para avaliar as propriedades biomecânicas de cada técnica. Baseado nisso, nossa pesquisa teve como objetivo fazer uma avaliação biomecânica comparando a força e rigidez promovidas por cinco diferentes técnicas de estabilização em coluna toracolombar (Pinos com Cimento Ósseo, Técnica Segmentar Modificada, Placa Bloqueada e Clamp Rod Internal Fixation utilizando parafusos monocorticais e bicorticais) frente às forças de compressão e flexão. Foram utilizadas 34 colunas tóraco-lombares de cães, divididas em cinco grupos. Para realização dos testes biomecânicos, foi utilizada a máquina de ensaios Kratos (modelo KE3000MP) e célula de carga de 100 kg. Para cada corpo de prova, três testes biomecânicos foram realizados, o controle, no segmento íntegro, após desarticulação de T13/L1 e após realização de uma das técnicas de estabilização propostas. Os dados foram exportados para análise estatística para o programa Statistical Package for the Social Sciences (SPSS) versão 18.0. Os resultados permitiram concluir que, apesar de não haver diferença estatística significativa, a Placa Bloqueada foi a técnica que promoveu maior rigidez e estabilidade nas vértebras lesionadas, seguida do CRIF bicortical, técnica Segmentar Modificada e Pinos e Cimento Ósseo. Estatisticamente, a Placa Bloqueada e o CRIF com parafusos bicorticais apresentaram maior rigidez e estabilidade em T13/L1 quando comparados com a técnica CRIF monocortical, que por sua vez, não alcançou rigidez necessária para adequada estabilização das vértebras.Spinal fractures and luxations resulting from trauma consist frequent disorder in clinical veterinary practice, being thoracolumbar spine the region that is the most commonly affected in canines, thus in many cases surgical treatment is necessary. There are several proposed techniques of implants to perform spinal stabilization; however, few studies of the thoracolumbar spine were carried out to evaluate the biomechanical properties of each technic. Therefore, the objective of the present study is to analyze biomechanical effects comparing the strength and the stiffness promoted by five different technics of stabilization in the thoracolumbar spine (pin with bone cement, modified segmental stabilization, locking plate and clamp rod internal fixation) under compression and bending forces. In the study, thirty four thoracolumbar dog spines were used, dividing the specimens in five groups. In order to perform the biomechanical tests, it was used a Kratos testing machine (model KE3000MP) and loading cell of 100 Kg. Each body of proof was submitted to three biomechanical tests, the control, in the segment intact, after disarticulation of the T13/L1 and after the realization of one of the proposed technics. Data were exported to statistical analyses to the Statistical Package for the Social Sciences (SPSS) version 18.0. The results led to the conclusion that despite there was no statistically significant difference between the techniques, the Locking Plate was the technique that promoted greater rigidity and stability in the injured vertebrae, followed by the Clamp Rod Internal Fixation bicortical, Modified Segmental Instrumentation and Pins with Bone Cement. Statistically, the locking plate and the Clamp Rod Internal Fixation with bicortical pins showed more stiffness and stability in T13/L1 when compared to the Clamp Rod Internal Fixation monocortical, which did not achieved the adequate rigidity for the stabilization of the vertebrae.
15
Hansson, Klas. "Water and Heat Transport in Road Structures : Development of Mechanistic Models." Doctoral thesis, Uppsala University, Department of Earth Sciences, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4822.
Full textAbstract:
The coupled transport of water and heat, involving freezing and thawing, in the road structure and its immediate environment is important to consider for optimal design and maintenance of roads and when assessing solute transport, of e.g. de-icing salt, from roads. The objective of this study was to develop mechanistic models, and measurement techniques, suitable to describe and understand water flow and heat flux in road structures exposed to a cold climate.
Freezing and thawing was accounted for by implementing new routines in two numerical models (HYDRUS1D/2D). The sensitivity of the model output to changes in parameter values and operational hydrological data was investigated by uncertainty and sensitivity analyses. The effect of rainfall event characteristics and asphalt fractures on the subsurface flow pattern was investigated by scenario modelling. The performance of water content reflectometers (WCR), measuring water content, was evaluated using measurements in two road structure materials. A numerical model was used to simulate WCR sensor response. The freezing/thawing routines were stable and provided results in agreement with laboratory measurements. Frost depth, thawing period, and freezing-induced water redistribution in a model road was greatly affected by groundwater level and type of subgrade. The simulated subsurface flow patterns corresponded well with published field observations. A new method was successful in enabling the application of time domain reflectometer (TDR) calibration equations to WCR output. The observed distortion in sampling volume for one of the road materials could be explained by the WCR sensor numerical model. Soil physical, hydrological, and hydraulic modules proved successful in simulating the coupled transport of water and heat in and on the road structure. It was demonstrated in this thesis that numerical models can improve the interpretation and explanation of measurements. The HYDRUS model was an accurate and pedagogical tool, clearly useful in road design and management.
16
Delgado, Navarro Betsabé Kelly. "Comparación In Vitro de la resistencia a la tensión diametral de dos resinas tipo Bulk Fill Aura® (SDI) Y Tetric-N-Ceram® (Ivoclar Vivadent) sometidas a dos bebidas energizantes Red Bull® Y Volt." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2018. http://hdl.handle.net/10757/623013.
Full textAbstract:
Objetivo: Comparar in vitro la resistencia a la tensión diametral de dos resinas tipo Bulk Fill Aura® (SDI) y Tetric-N-Ceram® sometidas a dos bebidas energizantes Red Bull® y Volt. Materiales y métodos: El estudio fue experimental in vitro. Se evaluaron 132 cuerpos de resina tipo Bulk Fill, los cuales se dividieron en seis grupos de 22 cuerpos de resina cada uno. Los grupos 1, 2 y 3 se realizaron con la resina Aura® (SDI) y los grupos 4, 5 y 6 con la resina Tetric-N-Ceram®. Los grupos 1 y 4 fueron sumergidos en la bebida energizantes Red Bull® y los grupos 2 y 5 en la bebida Volt por 10 min/ 1 vez al día durante 7 días; por otro lado, los grupos 3 y 6 fueron grupos control, solo sumergidos en agua destilada/7 días. Se evaluó la resistencia a la tensión diametral a través de la máquina de ensayo universal Instron® (velocidad de 0.5mm/min - carga 100 KN), medida en MPa. Para evaluar los resultados de cada una de las variables y realizar el análisis univariado se procedió a obtener medidas de tendencia central y medidas de dispersión. Para evaluar el análisis bivariado se procedió a realizar la prueba de Kruskal Wallis. Resultados: El grupo control de la resina Aura® presentó una media y una D.E de 46.51 + 3.14, mientras que el grupo control de la resina Tetric-N-Ceram® presentó 46.04 + 3.22. Se encontró que la resina Aura® al ser sumergida en la bebida Red Bull®, presentó una media y una D.E de 35.58 + 7.63, mientras que al ser sumergida en la bebida Volt, presentó 35.24 + 5.13. Por otro lado, la resina Tetric-N-Ceram® luego de ser sumergida en la bebida Red Bull® presentó una media y una D.E de 37.46 + 6.18, mientras que al ser sumergida en Volt presentó 36.15 + 6.74. Conclusiones: No existen diferencias estadísticamente significativas al evaluar la resistencia a la tención diametral de las resinas tipo Bulk Fill, sometidas a la bebida energizante Red Bull® (p= 0.796), ni a Volt (p= 0.496).Objective: Compare in vitro diametral tensile strength of two Bulk Fill Aura® (SDI) and Tetric-N-Ceram® type resins subjected to two Red Bull® and Volt energy drinks. Materials and methods: The study was experimental in vitro. 132 Bulk Fill type resin bodies were evaluated, which were divided into six groups of 22 resin bodies each. Groups 1, 2 and 3 were made with Aura® resin (SDI) and groups 4, 5 and 6 with Tetric-N-Ceram® resin. Groups 1 and 4 were submerged in the Red Bull® energy drink and groups 2 and 5 in the Volt energy drink for 10 min / 1 time a day for 7 days. On the other hand, groups 3 and 6 were control groups, only immersed in distilled water for 7 days. The diametral tensile strength was evaluated through the Instron® universal test machine (speed 0.5mm / min - load 100 KN), measured in MPa. To evaluate the results of each of the variables and perform the univariate analysis, we proceeded to obtain measures of central tendency and measures of dispersion. To evaluate the bivariate analysis, the Kruskal Wallis test was carried out. Results: The control group of the Aura® resin presented a mean and a S.D of 46.51 + 3.14, while the control group of the Tetric-N-Ceram® resin presented 46.04 + 3.22. It was found that the Aura® resin when submerged in Red Bull® presented an average and a S.D of 35.58 + 7.63, while when submerged in Volt, it presented 35.24 + 5.13. On the other hand, the Tetric-N-Ceram® resin after being submerged in the Red Bull® presented a mean and a S.D of 37.46 + 6.18, while when submerged in Volt it presented 36.15 + 6.74. Conclusions: There are no statistically significant differences when evaluating the resistance to the diametral tension strength of the Bulk Fill type resins, submitted to the Red Bull® energy drink (p = 0.796), or to Volt (p = 0.496).
17
Gutermann, Marc. "Ein Beitrag zur experimentell gestützten Tragsicherheitsbewertung von Massivbrücken." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2003. http://nbn-resolving.de/urn:nbn:de:swb:14-1062059931515-51848.
Full textAbstract:
In September 2000 the DAfStb issued a technical recommendation for the experimental assessment of structural safety and usability of concrete structures. By now, the influence of pavement or floor layers and of other factors on the load carrying capacity is not known exactly. In this thesis, it has been investigated how road pavements, the geometry and bridge caps reduce the actions on concrete bridge structures and how these influences should be taken into account in the experimental evaluation of the bending capacity by an additional test load increment. In co-operation with a local authority in Stralsund, Germany, comprehensive loading test could be performed at an abandoned concrete bridge with prefabricated girders. Between loading cycles, the pavement has been stepwise disassembled. In addition, the ultimate load of the structure as well as of an individual girder has been determined in fracture tests. By means of a hybrid analysis, i.e. a numerical simulation supported by experimental data, the influences of the pavement layers have been determined. These results were verified by experimental observations obtained in past bridge tests. The influence of the pavement layers on the load carrying capacity appeared to be as high as 28% at the maximum for the bridges investigated. Since the loading vehicle BELFA has been completed in March 2001, test loads can be applied now self-securing to bridges in the so-called large load circuit, i.e. the structure is loaded including supports and foundation. The technical concept, the principle and possible applications of the BELFA are described. The results presented will allow to determine the additional test load increment for compensating the influence of pavement layers, structural geometry and bridge caps in future experimental safety evaluations. For this analysis, the exact geometry of the structure, the thickness of the pavement layers as well as their material properties, especially the modulus of elasticity, have to be known. Guidelines for the analysis procedure as well as for simplifying assumptions are givenExperimentelle Nachweise der Tragsicherheit und Gebrauchstauglichkeit von Betonbauwerken sind seit September 2000 in einer DAfStb-Richtlinie geregelt. Der Einfluss mittragender Aufbauschichten und anderer Faktoren war bisher quantitativ unbekannt. In der vorliegenden Arbeit wurde untersucht, wie Straßenbeläge, Bauwerksgeometrie und Kappen die Beanspruchung der Tragkonstruktion von Massivbrücken mindern und im experimentellen Nachweis der Biegetragsicherheit durch eine Überlast zu berücksichtigen sind. In Zusammenarbeit mit dem Straßenbauamt Stralsund konnten an einer Fertigteilträgerbrücke Belastungsversuche mit sukzessivem Rückbau des Fahrbahnaufbaus sowie Bruchversuche am Gesamtsystem und an ausgebauten Fertigteilträgern mit Ortbetonergänzung erfolgen. Mit Hilfe der hybriden Statik, also der Modifikation und Evaluation von Rechnungen anhand experimentell erlangter Messwerte, wurden die Einflüsse der Aufbauschichten quantifiziert und durch Auswertung weiterer Brückenbelastungsversuche verifiziert. Der Einfluss der Aufbauschichten betrug bei den untersuchten Brücken bis zu 28%. Seit der Inbetriebnahme des Belastungsfahrzeuges BELFA im März 2001 können Versuchlasten auch im großen Kräftekreislauf, d.h. am Gesamtsystem einschließlich Auflager- und Gründungssituation, selbstsichernd aufgebracht werden. Die Entwicklung des BELFA, seine Funktionsweise und seine Einsatzmöglichkeiten werden erläutert. Mit den Ergebnissen dieser Arbeit ist es zukünftig möglich, die notwendige Überlast bei Belastungsversuchen zur Kompensation der Einflüsse aus Straßenbelag, Bauwerksgeometrie und Kappen mit genauem Aufmaß der Bauwerksgeometrie und der Schichtdicken sowie mit ingenieurmäßigem Abschätzen der Materialkennwerte (E-Moduli) hinreichend genau zu bestimmen. Handlungsempfehlungen geben Hinweise zur generellen Vorgehensweise sowie für vereinfachte Rechenannahmen
18
Gutermann, Marc. "Ein Beitrag zur experimentell gestützten Tragsicherheitsbewertung von Massivbrücken." Doctoral thesis, Technische Universität Dresden, 2002. https://tud.qucosa.de/id/qucosa%3A24260.
Full textAbstract:
In September 2000 the DAfStb issued a technical recommendation for the experimental assessment of structural safety and usability of concrete structures. By now, the influence of pavement or floor layers and of other factors on the load carrying capacity is not known exactly. In this thesis, it has been investigated how road pavements, the geometry and bridge caps reduce the actions on concrete bridge structures and how these influences should be taken into account in the experimental evaluation of the bending capacity by an additional test load increment. In co-operation with a local authority in Stralsund, Germany, comprehensive loading test could be performed at an abandoned concrete bridge with prefabricated girders. Between loading cycles, the pavement has been stepwise disassembled. In addition, the ultimate load of the structure as well as of an individual girder has been determined in fracture tests. By means of a hybrid analysis, i.e. a numerical simulation supported by experimental data, the influences of the pavement layers have been determined. These results were verified by experimental observations obtained in past bridge tests. The influence of the pavement layers on the load carrying capacity appeared to be as high as 28% at the maximum for the bridges investigated. Since the loading vehicle BELFA has been completed in March 2001, test loads can be applied now self-securing to bridges in the so-called large load circuit, i.e. the structure is loaded including supports and foundation. The technical concept, the principle and possible applications of the BELFA are described. The results presented will allow to determine the additional test load increment for compensating the influence of pavement layers, structural geometry and bridge caps in future experimental safety evaluations. For this analysis, the exact geometry of the structure, the thickness of the pavement layers as well as their material properties, especially the modulus of elasticity, have to be known. Guidelines for the analysis procedure as well as for simplifying assumptions are given.Experimentelle Nachweise der Tragsicherheit und Gebrauchstauglichkeit von Betonbauwerken sind seit September 2000 in einer DAfStb-Richtlinie geregelt. Der Einfluss mittragender Aufbauschichten und anderer Faktoren war bisher quantitativ unbekannt. In der vorliegenden Arbeit wurde untersucht, wie Straßenbeläge, Bauwerksgeometrie und Kappen die Beanspruchung der Tragkonstruktion von Massivbrücken mindern und im experimentellen Nachweis der Biegetragsicherheit durch eine Überlast zu berücksichtigen sind. In Zusammenarbeit mit dem Straßenbauamt Stralsund konnten an einer Fertigteilträgerbrücke Belastungsversuche mit sukzessivem Rückbau des Fahrbahnaufbaus sowie Bruchversuche am Gesamtsystem und an ausgebauten Fertigteilträgern mit Ortbetonergänzung erfolgen. Mit Hilfe der hybriden Statik, also der Modifikation und Evaluation von Rechnungen anhand experimentell erlangter Messwerte, wurden die Einflüsse der Aufbauschichten quantifiziert und durch Auswertung weiterer Brückenbelastungsversuche verifiziert. Der Einfluss der Aufbauschichten betrug bei den untersuchten Brücken bis zu 28%. Seit der Inbetriebnahme des Belastungsfahrzeuges BELFA im März 2001 können Versuchlasten auch im großen Kräftekreislauf, d.h. am Gesamtsystem einschließlich Auflager- und Gründungssituation, selbstsichernd aufgebracht werden. Die Entwicklung des BELFA, seine Funktionsweise und seine Einsatzmöglichkeiten werden erläutert. Mit den Ergebnissen dieser Arbeit ist es zukünftig möglich, die notwendige Überlast bei Belastungsversuchen zur Kompensation der Einflüsse aus Straßenbelag, Bauwerksgeometrie und Kappen mit genauem Aufmaß der Bauwerksgeometrie und der Schichtdicken sowie mit ingenieurmäßigem Abschätzen der Materialkennwerte (E-Moduli) hinreichend genau zu bestimmen. Handlungsempfehlungen geben Hinweise zur generellen Vorgehensweise sowie für vereinfachte Rechenannahmen.
19
Di, Nella Hélène. "Structure et cinématique de l'univers local." Université Joseph Fourier (Grenoble), 1995. http://www.theses.fr/1995GRE10220.
Full textAbstract:
Partie a, nous examinons les diverses procedures permettant de s'assurer de la completude d'un echantillon. Les echantillons extraits de la base de donnees leda nous permettent de re-identifier le plan hypergalactique qui regroupe 50% des galaxies de l'univers local dont les principaux superamas. Deux redshift surveys avec le spectro multifibre flair sont presentes. Nous trouvons une extension sud de la chaine de persee-poissons atteignant maintenant 150mpc et posant la question de la signification physique de la longueur de correlation de 5mpc des galaxies. Nous montrons que la longueur de correlation mesuree par la fonction de correlation a 2 points croit avec le rayon de l'echantillon. Nous expliquons ces resultats avec de nouveaux outils statistiques nous permettant de deriver une dimension fractale de 2 pour la distribution observee des galaxies. Partie b, nous proposons deux nouvelles methodes de calibration de l'echelle des distances des elliptiques. Les observations permettant de deriver le champ des vitesses propres sont presentees. Nous examinons ce champ de vitesses dans le plan hypergalactique. Partie c, nous presentons des simulations de la formation des grandes structures avec des conditions initiales homogenes ou fractales. Nous montrons qu'une distribution primordiale homogene pourrait evoluer vers une distribution fractale de dimension d=2
20
Lartigau, Julie. "Caractérisation du comportement des assemblages par goujons collés dans les structures bois." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2013. http://tel.archives-ouvertes.fr/tel-00922998.
Full textAbstract:
L'utilisation des goujons collés dans les structures bois répond au souci de conservation du bâti et de discrétion de l'intervention. A ce jour, plusieurs procédés de caractérisation et de dimensionnement sont disponibles, sans pour autant donner un socle commun à l'évaluation de la résistance des assemblages collés. L'utilisation des goujons collés suscite des interrogations concernant leur tenue au feu. Bien que le matériau bois entourant les tiges de renforcement soit isolant, il est nécessaire de fournir de plus amples estimations concernant la tenue mécanique des polymères pour différentes températures que l'on pourrait trouver au sein d'une liaison au cours d'un incendie. La présente étude permet de coupler méthodes expérimentales et simulations numériques, afin d'appréhender les mécanismes gouvernant la rupture de ces assemblages. La caractérisation expérimentale permet d'estimer les propriétés mécaniques locales des assemblages suivant divers paramètres (les longueurs de scellement, l'orientation du fil du bois, l'essence de bois, ou encore la température d'exposition), ainsi que les propriétés intrinsèques aux matériaux constitutifs. Cette base de données expérimentale est indispensable pour l'ajustement du modèle aux éléments finis en élasticité linéaire. L'approche numérique met en évidence une présence importante de contraintes normales en tête de collage, avant l'apparition de contraintes de cisaillement. Les outils de la Mécanique Linéaire Élastique de la Rupture équivalente permettent d'établir des courbes de résistance liées à chaque mode de ruine (mode I et mode II). Enfin, afin de décrire précisément le processus complet de rupture de ces assemblages, un critère de rupture en mode mixte (mode I et mode II) est utilisé. Une formulation analytique permettant d'estimer la charge au pic est proposée et permettra la réalisation d'abaques de dimensionnement des assemblages par goujons collés, utilisables en bureau d'études.
21
Lin, Yu-Kai, and 林裕凱. "Criterion of Core Fracture by Deviation-Velocity for Composite Clad Rod in Extrusion." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/99886267284818540944.
Full textAbstract:
碩士國立交通大學
機械工程系
89
The composite clad rod is a rod composed of two or more materials. It is applied extensively in industry because of its outstanding mechanical characteristics. However, when subject to extrusion the composite clad rod tend to develop non-uniform deformation because of these differences in materials’ mechanical properties. In certain cases, core fracture appears. The main object of this thesis is to investigate the criterion of core fracture for composite clad rod in extrusion. Upper-bound method was adopted for the analysis with a kinematically admissible velocity field to simulate the core and the sleeve’s uniform deformation under sound process parameter combinations, while a deviation-velocity field simulates the radial flow of core material. These two velocity fields are combined together with a designed variable applied to the deviation velocity component. When the total minimized power of extrusion indicates an existence of deviation velocity component, the initiation of the core fracture is deemed positive to occur. With this criterion for core fracture established, the extrusion work designed variable combinations is systematically investigated, and the work limit diagram for the composite clad rod in extrusion can be constructed.
22
Baker, Sean Travis. "Mechanical Assessment of Veterinary Orthopedic Implant Technologies: Comparative Studies of Canine Fracture Fixation and Equine Arthrodesis Devices and Techniques." Thesis, 2013. http://hdl.handle.net/1969.1/149599.
Full textAbstract:
The Clamp-Rod Internal Fixator (CRIF) is a fracture fixation implant with growing popularity among veterinarian’s for its versatility and ease of use. Although the CRIF is currently in clinical use, relatively few reports exist describing the biomechanical properties and clinical results of this system. The objective of this study was to determine the in vitro biomechanical properties of a 5mm CRIF/rod construct to a 3.5mm Limited Contact-Dynamic Compression Plate (LC-DCP/rod) construct using a canine femoral gap model.
Paired canine femora were treated with 40mm mid-diaphyseal ostectomies and randomly assigned to CRIF/rod or LC-DCP/rod. Five pairs of constructs were tested in bending and five pairs were evaluated in torsion. Single ramp to failure tests were conducted to evaluate construct stiffness, yield load, and failure mode.
While CRIF/rod and LC-DCP/rod were not significantly different when evaluated in bending, LC-DCP/rod constructs are significantly more rigid than CRIF/rod constructs at higher torsional loads. Below 10degrees of twist, or 4.92Nm torque, the LC-DCP/rod and CRIF/rod were not statistically different in torsion.
Catastrophic injuries of the metacarpophalangeal joint resulting in the disruption of the suspensory apparatus are the most common fatal injuries in thoroughbred racehorses. Fetlock arthrodesis is a procedure designed to mitigate suffering from injury as well as degenerative diseases affecting articulation. The objective of this study is to assess the in vitro biomechanical behavior of techniques for fetlock arthrodesis.
Twelve forelimb pairs were collected from adult horses euthanized for reasons unrelated to disease of the metacarpophalangeal joint (MCP). A 14-16-hole broad 4.5mm Locking Compression Plate (LCP) was compared to a 14-16 hole broad Dynamic Compression Plate (DCP). Both constructs used a two “figure-eight” 1.25mm stainless steel wire tension band. Fatigue tests and to failure tests were conducted.
There were no significant differences in stiffness between groups for fatigue tests. Stiffness increased after the first fatigue cycle for the LCP/wire (80.56+/-52.22%) and DCP/wire (56.58+/-14.85%). Above 3.5mm of axial deformation there was a statistical difference between the stiffness of the LCP/wire (3824.12+/-751.84 N/mm) and the DCP/wire (3009.65+/-718.25 N/mm) (P=0.038).
The LCP/wire showed increased stiffness above 3.5mm compression compared to the DCP/wire. Under fatigue testing conditions the constructs are not statistically different.
23
Chung, Fu-Wen, and 鐘福文. "Criterion for core fracture of Composite Clad Rods in Extrusion." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/97385864517180532344.
Full textAbstract:
碩士國立交通大學
機械工程系
88
Composite clad rods that are composed of two or more different materials being used extensive in the industry because of their excellent mechanical characteristics. However, owing to the different properties of the constituent materials, it is very often encountered various defects during extrusion process. In this study, the fracture of the core of the composite clad rods is our major object. We present a numerical simulation model based on the upper-bound theorem to analyze the core of composite clad rods in extrusion. Beside a normal three-dimensional admissible velocity fields that dictates the normal deformation of core and sleeve, an extra velocity fields depicts the necking of core is superimposed on this normal velocity fields. Both of the normal and the extra velocity fields are derived under the condition of incompressibility of materials or the constant volume flow. One pseudo-parameter was added on the extra velocity fields, while the total energy consumptions are subjected to minimization. If the result shows that a non-extra velocity fields exist, then we concluded core fracture would happen. Use the proposed criterion, combination of working parameters sound extrusion are established.
24
Wang, Ji. "Plate-Rod Microstructural Modeling for Accurate and Fast Assessment of Bone Strength." Thesis, 2016. https://doi.org/10.7916/D8125SQV.
Full textAbstract:
Progressive bone loss and weakening bone strength associated with aging predispose the elderly population to osteoporosis and millions of costly fragility fractures. Micro finite element (µFE) analysis based on clinical high-resolution skeletal imaging provides an accurate computational solution to assessing the mechanical properties of bone, which can be used as the dominant factors for fracture risk. However, the current µFE analysis technique is impractical for clinical use due to its prohibitive computational costs, which result from the “voxel-to-element” approach of modeling human bone regardless of its microstructural pattern. I developed a novel plate-rod microstructural modeling technique for highly efficient patient-specific µFE analysis and translated it to clinical research for the assessment of bone strength in osteoporosis and fragility fractures.
Trabecular microstructure is composed of interconnected plate-like and rod-like trabeculae. Instead of converting every image voxel directly into an element, the plate-rod modeling approach created mechanical characterization for every individual trabecular plate and rod. The validation studies demonstrated that the PR model was able to reproduce the morphology and mechanical behavior of the original trabecular microstructure, while reducing the size of the µFE model and improving the efficiency of µFE simulations. First, the PR models of trabecular bone were developed based on high-resolution micro computed tomography (µCT), and evaluated in comparison with computational gold standard-voxel µFE models and experimental gold standard-mechanical testing for estimating Young’s modulus and yield strength of human trabecular bone. Results suggested that PR model predictions of the trabecular bone mechanical properties were strongly correlated with voxel models and mechanical testing results. Moreover, the PR models were indistinguishable from the corresponding voxel models constructed from the same images in the prediction of trabecular bone Young’s modulus and yield strength. In addition, PR model nonlinear µFE analyses resulted in over 200-fold reduction in computation time compared with voxel model µFE analyses.
In the effort of studying the heterogeneous bone mineralization in trabecular plates and rods, I developed an individual trabecula mineralization (ITM) analysis technique that allows quantification of the tissue mineral density of each individual trabecular plate and rod. By examining the variation of mineral density with trabecular types and orientations, it was found that trabecular plates were higher mineralized than trabecular rods. Furthermore, trabecular plate mineral density varied with trabecular orientation, increasing from the longitudinal direction to the transverse direction. ITM provided measurement of mineral density of each trabecular plate and rod, which was converted to trabecula-specific tissue modulus and used in the PR models to incorporate mineral heterogeneity in µFE simulations. Results suggested that heterogeneous PR models did not differ from the homogeneous PR models or specimen-specific PR models in their predictions of apparent Young’s modulus and yield strength of the human trabecular bone specimens from non-diseased donors.
Based on the trabecular bone PR model, a whole bone PR model was developed for assessing whole bone mechanical strength at the distal radius and the distal tibia from high-resolution peripheral quantitative computed tomography (HR-pQCT). The accuracy of the whole bone PR model was evaluated on human cadaver radius and tibia specimens which were imaged using HR-pQCT and µCT, respectively, and tested to failure. The whole bone stiffness and yield load of the radius and tibia segments predicted by HR-pQCT PR models were strongly correlated with those predicted by corresponding HR-pQCT voxel models, µCT voxel models, and mechanical testing measurements. The PR models µFE results were indistinguishable from the voxel models constructed from the same HR-pQCT images. Moreover, the PR models significantly reduced the computational time for nonlinear µFE assessment of whole bone strength. After evaluating the accuracy and efficiency of the newly developed whole bone PR model, it was employed in a clinical study aimed at characterizing the abnormalities of trabecular plate and rod microstructure, cortical bone, and whole bone mechanical properties in postmenopausal women with vertebral fractures. Women with vertebral fractures had thinner cortical bone, and larger trabecular area compared to their non-fractured peers. ITS analyses suggested vertebral fracture subjects had deteriorated trabecular microstructure, evidenced by fewer trabecular plates, less axially aligned trabeculae and less trabecular connectivity at both radius and tibia. These microstructural deficits translated into reduced whole bone stiffness and yield load at radius and tibia as predicted by PR model nonlinear µFE simulation. More importantly, logistic regression indicated that whole bone yield load was effective in discriminating the vertebral fracture subjects from the non-fractured controls.
25
林昇立. "A study on core fracture and metal flow during extrusion of bimetal rods." Thesis, 1987. http://ndltd.ncl.edu.tw/handle/17989833980433293088.
Full text
26
Katsikogianni, Maria G., R. E. W. Hancock, D. A. Devine, and David J. Wood. "Cell vs. bacterial viability in the presence of host defence peptides and RGD." 2015. http://hdl.handle.net/10454/11521.
Full textAbstract:
yesMore than 2 million people/year suffer a bone fracture in the UK1. Reconstruction of bone defects represents a major clinical challenge and is addressed using a number of medical devices. Although medical device compositions and applications may differ widely, all attract microorganisms and represent niches for medical device associated infections. For open fractures, the risk of infection can be 55%2. These infections are often resistant to many of the currently available antibiotics and represent a huge and growing financial and healthcare burden. The aim of this study was a fundamental understanding of how the presence of host defence peptides (HDPs)3 and/or RGD can influence the outcome of cell vs. bacterial viability and proliferation.
Presented at the conference: eCM XVI - Bone and Implant Infection June 24-26, 2015, Convention Centre, Davos Platz, Switzerland.
27
Lawson, Joshua Lee. "The importance of geologic setting in developing groundwater from fractured, metamorphic rock aquifers in the vicinity of the Gwinnett County Airport and Collins Hill Road, Gwinnett County, Georgia." 2003. http://purl.galileo.usg.edu/uga%5Fetd/lawson%5Fjoshua%5Fl%5F200305%5Fms.
Full text