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Dissertations / Theses on the topic 'Fracture'

Author: Grafiati

Published: 4 June 2021

Last updated: 26 October 2024

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1

Fatahi, Hassan. "Simulation of Hydraulic Fracture Propagation Interacted with Natural Fractures." Thesis, Curtin University, 2016. http://hdl.handle.net/20.500.11937/51882.

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This study developed an advance understanding of the mechanisms of hydraulic fracture initiation, propagation, and natural fractures interaction based-on thorough investigation of effects of various parameters associated with hydraulic and natural fractures through numerical modelling, simulation and laboratory experiments. Thesis progressively demonstrates different steps of the development of numerical modelling, simulation and experimental validation. Factors influencing the initiation and propagation of hydraulic fracture, and natural fractures interactions are thoroughly discussed based upon comprehensive sensitivity studies.

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2

Selle, Andrew. "Fracture." Bowling Green State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1427153464.

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3

Gross, Matthew Edward. "Discrete fracture modeling for fractured reservoirs using Voronoi grid blocks." Texas A&M University, 2003. http://hdl.handle.net/1969.1/5777.

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Fractured reservoirs are commonly simulated using the Dual Porosity model, but for many major fields, the model does not match field results. For these cases, it is necessary to perform a more complex simulation including either individual fractures or pseudofracture groups modeled in their own grid blocks. Discrete Fracture Modeling (DFN) is still a relatively new field, and most research on it up to this point has been done with Delaunay tessellations. This research investigates an alternative approach using Voronoi diagrams, yet applying the same DFN principles outlined in previous works. Through the careful positioning of node points, a grid of Voronoi polygons can be produced so that block boundaries fall along the fractures, allowing us to use the DFN simulation methods as proposed in the literature. Using Voronoi diagrams allows us to use far fewer polygons than the Delaunay approach, and also allows us to perfectly align flow so as to eliminate grid alignment errors that plagued previous static systems. The nature of the Voronoi polygon further allows us to simplify permeability calculations due to orthogonality and, by extension, is more accurate than the commonly used cornerpoint formulation for non-square grid blocks.

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4

Kim, Tae Hyung. "Fracture characterization and estimation of fracture porosity of naturally fractured reservoirs with no matrix porosity using stochastic fractal models." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-2570.

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5

Marchais, Jean-Philippe. "La fracture des corps caverneux." Bordeaux 2, 1993. http://www.theses.fr/1993BOR2M109.

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6

Lolon, Elyezer P. "Evaluation of the relationship between fracture conductivity, fracture fluid production, and effective fracture length." Texas A&M University, 2004. http://hdl.handle.net/1969.1/3050.

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Low-permeability gas wells often produce less than predicted after a fracture treatment. One of the reasons for this is that fracture lengths calculated after stimulation are often less than designed lengths. While actual fracture lengths may be shorter due to fracture growth out of zone, improper proppant settling, or proppant flowback, short calculated fracture lengths can also result from incorrect analysis techniques. It is known that fracturing fluid that remains in the fracture and formation after a hydraulic fracture treatment can decrease the productivity of a gas well by reducing the relative permeability to gas in the region invaded by this fluid. However, the relationships between fracture fluid cleanup, effective fracture length, and well productivity are not fully understood. In this work I used reservoir simulation to determine the relationship between fracture conductivity, fracture fluid production, effective fracture length, and well productivity. I simulated water saturation and pressure profiles around a propped fracture, tracked gas production along the length of the propped fracture, and quantified the effective fracture length (i.e., the fracture length under single-phase flow conditions that gives similar performance as for multiphase flow conditions), the "cleanup" fracture length (i.e., the fracture length corresponding to 90% cumulative gas flow rate into the fracture), and the "apparent" fracture length (i.e., the fracture length where the ratio of multiphase to single-phase gas entry rate profiles is unity). This study shows that the proppant pack is generally cleaned up and the cleanup lengths are close to designed lengths in relatively short times. Although gas is entering along entire fracture, fracturing fluid remains in the formation near the fracture. The water saturation distribution affects the gas entry rate profile, which determines the effective fracture length. Subtle changes in the gas rate entry profile can result in significant changes in effective fracture length. The results I derived from this work are consistent with prior work, namely that greater fracture conductivity results in more effective well cleanup and longer effective fracture lengths versus time. This study provides better explanation of mechanisms that affect fracturing fluid cleanup, effective fracture length, and well productivity than previous work.

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7

Chung, Wai-Nang. "Fracture toughness and creep fracture studies of polyethylenes." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46720.

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8

Daming, Duan. "Fracture toughness and term fracture behaviour of polyethylenes." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243909.

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9

Helden, Svenhjalmar van. "Looking beyond the fracture prevention in fracture care /." [Maastricht] : Maastricht : [Maastricht University] ; University Library, Universiteit Maastricht [host], 2008. http://arno.unimaas.nl/show.cgi?fid=13442.

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10

Wang, Mingyu. "Discrete fracture fluid flow modeling and field applications in fractured rocks." Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/284182.

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Fluid flow modeling in fractured rocks is a complicated and important research and application topic in many fields such as geological, hydrogeological, environmental and petroleum engineering. Commonly used methods based on equivalent continuum assumption for fluid flow modeling can generally be applied directly to the porous geological media, but have limited applicability when the geological medium is dominated by fractures. It often happens that only limited time, cost, hydrogeological data and computer resources are available in solving a practical problem of the fluid flow modeling in fractured rocks. Therefore, it is a challenge, but necessary, to investigate the hydraulic behaviors and propose new approaches, procedures, and methodologies to build a reliable fluid flow model for fractured rocks with limited available related data. The general concepts on fluid flow modeling in fractured rocks are introduced firstly and the different ways to treat major and minor fractures in 2-D and 3-D discrete fracture fluid flow modeling are propounded. The author has investigated the relations between the hydraulic behaviors and fracture geometry parameters and found out the effect of fracture parameters on the Representative Elementary Volume (REV) for the fracture systems with statistically distributed fracture geometry parameters including the size, orientation and location. Further, a systemic procedure for fluid flow modeling in fractured rocks in two-dimensional domain is suggested and demonstrated through a 2-D case study for groundwater resources evaluation. Six 3-D conceptual linear pipe discrete fracture fluid flow models which focus on the utilization of fracture information are proposed to simulate packer or pumping tests conducted in fractured rock masses. These models can reflect channel flow in fractures, simplify and minimize the complexity of fluid flow in fractures, save computer resources and increase the possibility to solve a field problem at large scales, and implement a discrete fracture fluid flow model easily. Finally, the author has developed a practicable systemic approach to determine the REV for hydraulic properties and then the hydraulic conductivity tensor for the REV in fractured rocks using single well packer test results. These procedures are illustrated through a 3-D case study by implementing the proposed fluid flow models.

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11

Akisanya, Alfred Rotimi. "Interfacial fracture." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334108.

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12

Bonnard, Olivier. "Les fractures du calcaneum de l'adulte : à propos d'une série de 135 cas : travail du service d'orthopédie traumatologie du professeur Bousquet, CHRU Saint-Etienne." Saint-Etienne, 1990. http://www.theses.fr/1990STET6415.

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13

Cariou, Luc. "La fracture Tear drop." Bordeaux 2, 1996. http://www.theses.fr/1996BOR23048.

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14

Samsami, Shabnam [Verfasser], and Peter [Akademischer Betreuer] Müller. "Fracture fixation of complex tibial plateau fractures / Shabnam Samsami ; Betreuer: Peter Müller." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2021. http://d-nb.info/1234389134/34.

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15

何柏康 and Pak-hong Henry Ho. "A new implant for distal radius fracture fixation: from design to testing." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31226061.

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16

Stehn, Lars. "Tensile fracture of ice : test methods and fracture mechanics analysis." Doctoral thesis, Luleå tekniska universitet, Byggkonstruktion och -produktion, 1993. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-18394.

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This thesis is concerned with several aspects of fracture of both brackish (low salinity) sea ice and freshwater ice. The tests and analyses are confined to tensile, or in fracture mechanics language, Mode I, fracture. A large part of this thesis is dedicated to demonstrate that Linear Elastic Fracture Mechanics (LEFM) can be applicable on ice by laboratory and in-situ tests of defined specimens. All interpretations are made using the dicipline of LEFM.First, the development of a field test equipment called FIFT ( a Field Instrument for Fracture toughness Tests on ice) is described. The FIFT is used in both field and laboratory fracture toughness tests on brackish sea ice from the Gulf of Bothnia to describe porosity effects on the apparent fracture toughness, KQ, and estimate crack velocities. An appropriate speciment size, in terms of notch sensitivity, is then provided valid for grain sizes ranging from 1.6 to nearly 100 mm.An augmented use of the FIFT is then described where fracture toughness tests are performed on S1 type freshwater ice to investigate if similarities exist in the local KI fields for three different fracture geometries. The results indicate that, under comparable conditions, KQ is similar for all of the geometries. However, the type of specimen, has a marked influence on the character of the fracture surface.Then, the influence of structural anisotropy on the fracture toughness of S1 ice is investigated by fabricating and testing three different fracture geometries from a single ice core. This approach is suitable for both field and, as in this work, laboratory studies. There is a wide scatter in the KQ values. Possible explanations to the results are discussed in terms of the microstructural influences and specimen size effects.Finally, crack growth resistance measurements on large grained S1 ice is conducted. A new fracture geometry is used which is found to be extremely favorable of promoting stable, stick-slip, crack growth over a large portion of the uncracked ligament. Now a complete characterization of the fracture resistance curve is therefore possible, A negative fracture resistance KR-curve is evaluated for the S1 ice at -16°C.
Godkänd; 1993; 20070426 (ysko)

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17

Al-Mahruqi, Salim Ali Salim. "Fracture patterns and fracture propagation as a function of lithology." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249556.

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18

AlDajani, Omar AbdulFattah. "Fracture and hydraulic fracture initiation, propagation and coalescence in shale." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/109646.

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Thesis: S.M., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2017.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 152-154).
Even though hydraulic fracturing has been in use for more than six decades to extract oil and natural gas, the fundamental mechanism to initiate and propagate these fractures remains unclear. Moreover, it is unknown how the propagating fracture interacts with other fractures in the Earth. The objective of this research is to gain a fundamental understanding of the hydraulic fracturing process in shales through controlled laboratory experiments where the underlying mechanisms behind the fracture initiation, -propagation, and -coalescence are visually captured and analyzed. Once these fundamental processes are properly understood, methods that allow one to produce desired fracture geometries can be developed. Two different shales were investigated: the organic-rich Vaca Muerta shale from the Neuquén Basin, Argentina and the clay-rich Opalinus shale from Mont Terri, Switzerland, which were shown to vary in mineralogy and mechanical properties. Specimen preparation techniques were developed to successfully dry cut a variety of shales and produce prismatic specimens with pre-existing artificial fractures (flaws). The Vaca Muerta shale specimens were subjected to a uniaxial load which induces fractures emanating from the flaws. Two geometries were tested: a coplanar flaw geometry (2a-30-0) resulting in indirect coalescence and a stepped flaw geometry (2a-30-30) resulting in direct coalescence. These "dry" fracture experiments were analyzed in detail and corresponded well to the behavior observed in the Opalinus shale. This result shows that the fracture behavior in Opalinus shale can be extended to other shales. A test setup capable of pressurizing an individual flaw in prismatic shale specimens subjected to a constant uniaxial load and producing hydraulic fractures was developed. This setup also allows one to monitor internal flaw pressure throughout the pressurization process, as well as visually capture the processes that occur when the shale is hydraulically fractured. Three fracture geometries in Opalinus shale were tested using this developed setup: single vertical flaw (SF-90) for the proof of concept of the test setup, stepped flaw geometry (2a-30-30) which resulted in no coalescence, and stepped flaw geometry (2a-30-60) which resulted in indirect coalescence. Of particular interest were the observed lag between the crack tip and the liquid front as well as the way the hydraulic fracture propagates across and along bedding planes. A systematic difference was observed when comparing crack interaction behavior for "dry" and hydraulic fracture experiments for various flaw geometries. The result of this thesis will add to fundamental knowledge of how fractures behave and interact under various loading conditions, flaw geometries, and materials serving as a basis for predictive fracture models.
by Omar AbdulFattah AlDajani.
S.M.

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19

Skoglund, Björn. "Following the mevalonate pathway to bone heal alley /." Linköping : Department of Clinical and Experimental Medicine, Materials in Medicine, Section of Orthopaedics and Sports Medicine, Faculty of Health Sciences, Linköping University, 2007. http://www.bibl.liu.se/liupubl/disp/disp2007/med1033s.pdf.

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20

Wade, Roger. "Defining fracture union." Thesis, Keele University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249450.

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21

Sandberg, Olof. "Metaphyseal Fracture Healing." Doctoral thesis, Linköpings universitet, Avdelningen för kliniska vetenskaper, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-126148.

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Most of what is known about fracture healing comes from studies of shaft fractures in long bones. In contrast, patients more often have fractures closer to the ends (metaphyses). Here most bone tissue has a spongy, cancellous structure different from the compact bone of the shaft. There is an increasing awareness that metaphyseal fractures heal differently. However, the more easily studied shaft healing has usually been considered as good enough representative for fracture healing in general. My work shows that the biology of metaphyseal healing is more different from shaft healing than was previously known and that this has implications on the effect of various commonly prescribed drugs. First we studied biopsies of healing cancellous bone collected from human donors. We found that the most abundant new bone formation occurred freely in the marrow rather than on the surface of old trabeculae, as described in most literature. There was little cartilage, indicating that the dominant bone formation process is mostly membranous in nature. This is a contrast to the ample cartilage formation commonly found in the well-characterized shaft fracture models. Next we characterized a model that allows for mechanical quantification of regenerating cancellous bone. By contrasting this cancellous healing model with the standard shaft healing model we could demonstrate that the NSAID indomethacin, the glucocorticoid dexamethasone, and the bisphosphonate alendronate all had different effects on the mechanical quality of bone regeneration in shaft and metaphysis; while anti-inflammatory drugs strongly impaired shaft healing, metaphyseal healing was not similarly affected. Alendronate had a positive effect on both models, though the effect was strongest in the metaphyseal model. Taken together these differences shed some light as to the differences in healing biology. The last step (within the boundaries of this thesis) was a characterization of how healing in cortical and cancellous bone differs in terms of immune cell involvement. We could find little difference between the two bone types day 3. However, day 5 an increase in the number of granulocytes could be noted in the cancellous bone while the cortical bone had a higher number of lymphocytes. To conclude, this work furthers our understanding of how metaphyseal healing differs from shaft healing. It has clinical implications as it motivates an increased attention to the site of fracture while contemplating treatment. I hope this thesis can be read as an argument for increased interest in metaphyseal fracture healing.

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22

Dias, Joseph Joaquim. "Scaphoid fracture union." Thesis, University of Leicester, 1989. http://hdl.handle.net/2381/34325.

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Scaphoid fracture union depends upon early diagnosis and adequate management and is considered to be adversely influenced by proximal scaphoid avascularity and carpal instability. There is, however, controversy on various aspects in the diagnosis and management of this injury. Studies investigating some of these aspects are reported in this thesis. With regard to the initial diagnosis of this fracture this thesis demonstrated that the fracture was usually visible on the 'Ziter' or the posterio-anterior radiographic view while radiographic evaluation of soft tissue swelling was of less value than that suggested by current literature. Moreover, the second week radiograph did not provide reliable evidence of a fracture in those suspected on clinical examination alone. Normal lines in an intact scaphoid could be mis-interpreted as a fracture. With regard to management, the fracture healed equally well in a Colles' cast: thumb immobilisation did not appear to be neccessary. The incidence of non-union was around 12% and most were symptomatic. A further 25%, in whom the fracture site was easily identified but appeared to have healed, formed a distinct clinical group and many had symptoms. The reliability and reproducibility of radiographic signs of union were poor. Therefore, a real time ultrasonographic method of demonstrating movement at the scaphoid fracture site was developed. Proximal avascularity was more common than that suggested by radiographic appearances alone while carpal instability was uncommon within two years of injury. Based on these observations a rational approach to management of scaphoid fractures was proposed.

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23

Gerde, Eric Stendahl. "Fracture and friction /." Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3008334.

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24

Zwart, Salmerón Marta. "Estudis de cohorts per validar un model de categorització del risc de fractura per fragilitat en població femenina espanyola en base a l’algoritme FRAX ® de la OMS. Les cohorts FRIDEX i FROCAT." Doctoral thesis, Universitat Autònoma de Barcelona, 2016. http://hdl.handle.net/10803/399848.

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Estudis internacionals han demostrat la utilitat de l'eina FRAX de l’Organització Mundial de la Salut (OMS) per a l'estimació del risc absolut de fractura osteoporòtica a 10 anys. S’ha evidenciat que a població femenina espanyola l'eina té una bona capacitat de discriminació per detectar dones que patiran una fractura per fragilitat de les que no, i que millora el model tradicional basat en la densitometria òssia (T-score ≤ -2.5 desviacions estandars (DE)). No obstant això, l’algoritme mostra una manca de concordança global entre la probabilitat estimada de fractura i la incidència de fractura observada individual a 10 anys, amb una tendència a infraestimar el risc. Per millorar la capacitat predictiva de fractura osteoporòtica principal s’ha desenvolupat el model FRIDEX, amb 3 categories de risc FRAX (calculat sense T-score de coll femoral) per població femenina espanyola (<5%; ≥5 a <7,5%; ≥7,5%) que iclouen la incidència de fractures observades en la cohort, les quals estaven, al seu torn, respectivament dins els nivells tradicionalment considerats com de risc baix (<10%), intermig (10-20%) i alt (> 20%) en altres estudis epidemiològics. L’objectiu d’aquesta tesi doctoral va ser validar aquest model FRIDEX de calibració del risc de fractura per fragilitat en població femenina espanyola en base a l’algoritme FRAX en la cohort ampliada FRIDEX i en la població general (cohort FROCAT). En primer lloc els resultats del treball validen les interpretacions de la capacitat discriminativa i predictiva de l’eina FRAX obtingudes en les primeres anàlisi de la cohort FRIDEX i, és important perquè d’aquests casos es va desenvolupar la proposta per categoritzar el risc de fractura en dones espanyoles. En segon lloc, validen externament el model FRIDEX de discriminació del risc de fractura principal a 10 anys en una cohort de dones de base poblacional i diferent de la cohort que ha servit per establir-lo.
The usefulness of the FRAX tool from the World Health Organization to evaluate the 10-year fracture risk of patients has been shown in many international studies. In the Spanish female population it has been demonstrated that the tool has a a good discriminative ability to detect women who will suffer from a fragility fracture and it is at least equivalent to, if not slightly higher than the bone mineral density (BMD) model (T-score ≤ -2.5 standard deviations). However, it displays weaknesses in the overall concordance between predicted fracture probability and observed fracture incidence, with a tendency to underestimate the risk. To improve the main osteoporotic fracture risk predictive capability, some FRAX thresholds have been developped to identify people with risk of osteoporotic fracture in Spain, based on the stratification from the female FRIDEX cohort into 3 levels of FRAX risk ( without femoral neck (FN) T-score) (low risk <5%, intermediate ≥5 to <7.5% and high ≥7.5%) according to the fracture incidence observed in the cohort, which in turn are related with risk ranges traditionally considered to be low (<10%), intermediate (10-20%) and high risk (> 20%) in other epidemiological studies. The aim of this thesis was to validate the FRIDEX model in the Spanish female population using the FRAX main osteoporotic fracture risk thresholds to 10-year in the updated results of the FRIDEX cohort and in the general population (FROCAT cohort). Firstly, the work validates the discriminatory and predictive ability of the FRAX tool obtained in the preliminary analysis of the FRIDEX cohort, and this is important because from these cases the categorization in the three risk groups was developed. Secondly, it externally validates the FRIDEX model to discriminate fracture risk in women from the general population.

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25

Mdlalose, Lindubuhle. "Immediate versus delayed surgical management of septic mandibular fractures." Thesis, University of the Western Cape, 2015. http://hdl.handle.net/11394/4611.

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Magister Scientiae Dentium - MSc(Dent)
Aim: The aim of the study was to compare immediate and delayed surgical management of septic mandibular fractures. Introduction: Infected mandible fractures can be treated via diverse protocols. Two recognized protocols are the so-called delayed approached and the immediate approach. In the delayed approach, sepsis is resolved first, followed by surgery. With the immediate approach, the sepsis is first drained, followed by open reduction and internal fixation of the jaw fracture in one continuous surgical procedure. Material and methods: 20 clinical cases where included in the study. Patients were randomly selected and assigned to the two treatment protocol groups. Pain, vital signs, fracture union, fracture stability, surgical time, hospital time, follow-up visits and patients’ demographics were recorded. Results: No statistically significant findings were made in the analysis of the demographic data and clinical parameters relating to the sepsis. The only significant data were related to the surgical time and hospital time. It was found that the advantages of the immediate approach versus the delayed approach related only to shorter surgical time and less days spent in hospital for the immediate approach. Conclusion: Septic mandibular fractures can be managed either by an immediate or a delayed approach. The immediate surgical approach seems to have an advantage over the delayed approach regarding the surgical time and hospital admission days.

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26

Stankewich, Charles J. "The hip fracture epidemic : prevention and treatment strategies /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/8088.

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27

Cheng, Yuqing. "A Mathematical Model to Predict Fracture Complexity Development and Fracture Length." Thesis, University of Louisiana at Lafayette, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10246182.

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Hydraulic fracturing is a commonly used practice in stimulation treatment, especially in low-permeability formation. The fracture complexity usually took place in relation to the interaction between fractures and natural rock fabrics. Despite many studies regarding the production simulation, diagnostic methods, and mathematical models about fracture complexity, research about the local complexity development is still needed for optimized stimulation design. Aiming to predict the local complexity development and stimulation performance, a hierarchy model is designed to make the problem more tractable, and a corresponding mathematical model is developed for numerical simulation. A case study is provided, and the comparison with the result of micro-seismic mapping indicates much discrepancy between field data and simulated result. Considering the many limitations of the model, the discrepancy is tolerable and acceptable. According to the sensitivity analysis, a high injection rate could serve to increase fracture complexity while reducing the maximum length of fractures. The sensitivity analyses regarding bottom-hole net pressure show a weak relationship between the fracture complexity and the bottom-hole net pressure, but a high injection pressure or low in-situ stress can serve to enhance the stimulation performance by increasing the maximum length of fractures. Sensitivity analyses for fluid properties indicate that using the high-viscosity fracturing fluid can add to the local complexity of fractures and reduce the maximum length of fractures, while fluid density has little to do with the fracture complexity and stimulation performance. The parametric study regarding rock surface energy indicates little effect of surface energy of different shale rocks on changing the local fracture complexity and stimulation performance.

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28

Dang, Hong Lam. "Modélisation du comportement hydromécanique des réservoirs fracturés à double porosité et double perméabilité." Thesis, Orléans, 2018. http://www.theses.fr/2018ORLE2001/document.

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La modélisation des massifs rocheux fracturés est un problèmes important dans de nombreux secteurs industriels, y compris, mais sans s'y limiter à l'exploitation pétrolière et gazière. Dans la littérature, les roches fracturées sont reconnues comme des milieux à double porosité et double perméabilité dans lesquels le réseau de fractures fournit la perméabilité primaire et la matrice rocheuse la perméabilité secondaire. L'idée de la dissociation de l'écoulement à l'intérieur du réseau de fractures et de la matrice,la double perméabilité, est toujours contestée pour les réservoirs fracturés. De nombreuses contributions sur cette question ont été présentées dans la littérature et les méthodes utilisées pourraient être classées dans deux approches principales : approches continues et discontinues. Chaque approche a ses avantages et ses limites. Pour surmonter les limites en gardant les avantages de ces deux approches, une approche nommée Embedded Fracture Continumm Approach (EFCA) qui emprunte le concept du modèle continu et intègre également l'effet des fractures explicites est considérée dans cette thèse. L'idée principale de cette approche repose sur le concept de la « cellule fracturée » représentant un milieu poreux qui a ses propres propriétés calculées à partir des propriétés de la matrice poreuse et des fractures qui la traversent. Le code de calcul développé dans le cadre de ce travail est basé sur la bibliothèque source DEAL.II. L'exactitude de l'EFCA a été étudiée à travers de différents tests. Plusieurs applications traitées dans ce travail comme la détermination des propriétés hydro-mécaniques effectives d'un site réel, estimation de la production de puits dans laquelle les fractures sont modélisées explicitement, démontrent la performance de l'EFCA dans la modélisation des roches fracturées ainsi que l'effet de la double porosité et de la double perméabilité aux comportements des réservoirs fracturés
Fractured rock masses modeling is a challenge issue in many field of industry including but not limited to oiland gas exploitation. In the literature, fractured rock masse are in many cases recognized as double permeability medium in which fracture network provides the primary permeability and rock matrix plays asthe second one. The idea of dissociation of flow inside the fracture network and the matrix, the double permeability, is still challenged for fractured reservoirs. Numerous contributions on this issue have been presented in the past could be cast in two main approaches: continuum media approach and discontinuous approach. Each approach has its advantages and limitations. To overcome the limitation and to take advantage of these two approaches, the Embedded Fractured Continuum Approach (EFCA) which borrows the concept of continuum models and also incorporates the effect of explicit fractures is considered in this thesis. The principal idea of this approach lies on the concept of fracture cell representing a porous medium that has their own properties calculated from the properties of porous matrix and fractures intersecting it.The development in this work was conducted by using the library source code DEAL.II. The accuracy of EFCA was investigated through different verifications. Through some applications: determination of effective hydro-mechanical properties of an actual site, estimation of well production in which necessary fractures are modeled explicitly, we demonstrate the performance of the EFCA in the modeling fracture drock masses as well as the effect of double porosity and double permeability on behaviours of fractured reservoirs

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29

Kitshoff, Adriaan Mynhardt. "Comparative biomechanics of two non-invasive mandibular fracture repair techniques in dogs." Diss., University of Pretoria, 2012. http://hdl.handle.net/2263/30897.

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30

Jrad, Rami. "Etude rétrospective d'un an de fractures des membres chez les enfants de moins de seize ans au C. H. G. De Perpignan." Montpellier 1, 1996. http://www.theses.fr/1996MON11024.

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Kasturi, Krishna Kumar. "Microcracking Fracture Toughness for Graphite Epoxy Composite Laminates Using Finite Fracture Mechanics." ScholarWorks@UNO, 2006. http://scholarworks.uno.edu/td/427.

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Graphite/epoxy composite laminates are widely used in the aerospace industry. However the industry cannot take full advantage of the superior strength and stiffness of composite materials until their failure mechanisms can be thoroughly understood by engineers. Recognizing the importance of such understanding, the current study was undertaken to determine the microcracking fracture toughness in composite laminates using the energy release rate criteria. Three materials of specific interest in the aerospace industry – IM7/977-2, IM7/5555 and IM7/5276-1 – were analyzed. To evaluate the microcracking fracture toughness, displacement controlled static tensile tests were performed. Microcrack density (the number of microcracks per unit length) was measured as a function of applied stress. The data were analyzed to obtain the microcracking fracture toughness (Gm) for each material system. The value of Gm can be used to predict the microcracking behavior of composite laminates made from the corresponding material.

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32

To, Theany. "Fracture toughness and fracture surface energy of inorganic and non-metallic glasses." Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1S013/document.

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La ténacité et l’énergie de surface de fracture de verres, de vitrocéramiques et de composites à matrice en verre ont été étudiées. Tout d'abord, un test de flexion bi-axiale (configuration anneau/anneau) a été réalisé sur des verres de silice et des verre-à-vitres avec différentes conditions de surface afin d’identifier la relation entre le défaut de surface, la résistance et la ténacité du verre. Ensuite, trois méthodes d’expérimentation ont été mises en œuvre, principalement la méthode de poutre de flexion à pré-entaille droit (SEPB), la méthode de la poutre entaillée en chevron (CNB) et la méthode de la poutre avec indentations Vickers (VIF), afin de déterminer la ténacité de quatre verres produits industriellement et de déterminer les avantages et les inconvénients des différents méthodes sélectionnées. La méthode qui est apparue la plus fiable et auto-cohérente, la méthode SEPB (Single Edge Precrack Beam), a été appliquée à la détermination de la ténacité de nombreux verres et vitrocéramiques, afin d’étudier l’influence de la composition et de la microstructure sur les caractéristiques de fissuration (KIC et énergie de fissuration, γ). Enfin, l’influence de la température et de l'environnement sur la ténacité a été étudiée à l'aide de la méthode SEPB. Deux verres d'oxyde ont été testés à des températures élevées et avec une vitesse de charge de 10 MPa∙√m/s, une température de transition de 1,11Tg a été trouvée. Quatre autres verres d'oxyde ont été testés en environnement inerte et les mêmes valeurs de ténacité ont été obtenues à partir de deux vitesses de charge (100 fois) différentes
Fracture toughness and fracture surface energy of commercial and laboratory glasses, glass-ceramics and glass matrix composites have been studied. First, bi-axial bending test (RoR configuration) was performed on fused silica and window float glasses with different surface conditions to identify the relationship between the surface flaw, the strength and fracture toughness. After, three experiment methods, mainly single-edge precracked beam (SEPB), chevron-notched beam (CNB) and Vickers indentation fracture (VIF) were performed to determine the fracture toughness of four commercial known glasses and to determine the advantages and inconveniences of the different selected methods. The method that is appeared as the most reliable and self-consistent, the SEPB (Single Edge Precrack Beam) method, was applied to determine the toughness of the large amount of glasses and glass-ceramics, to study the influence of the composition and the microstructure on the characteristics of cracking (KIC and fracture energy, γ). Last but not least, the influence of the temperature and environment on the fracture toughness was studied by means of the SEPB method. Two oxide glasses were tested in elevated temperatures and with the loading rate of 10 MPa∙√m/s, a transition temperature of 1.11Tg was found. Four other oxide glasses were tested in the inert environment and the same fracture toughness values were obtained from (100 times) two different cross-head speeds

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Debertrand, Louis. "Fracture of dual-crosslink dynamic hydrogels : from molecular interactions to fracture energy." Electronic Thesis or Diss., Université Paris sciences et lettres, 2020. http://www.theses.fr/2020UPSLS027.

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Ce projet s'insère dans un projet global plus ambitieux dont l'objectif est de comprendre les mécanismes de la propagation d'une fracture au sein d'un matériau mou. Les matériaux étudiés lors de cette thèse seront principalement des hydrogels, "classiques" ou à double réticulation chimique/physique. L'introduction de liens dynamiques permet de retarder la rupture des liens covalents et augmente l'énergie de rupture. A ce jour, il n'existe aucun modèle d'endommagement qui permette de prédire la rupture à partir de la structure moléculaire. L'objectif est donc de combiner différentes techniques pour détecter la rupture à plusieurs échelles. Au niveau macroscopique ce sera la vitesse de propagation d'une fissure et les conditions de son amorçage qui seront étudiées. A l'échelle mésoscopique le champ de déformation en pointe de fissure sera étudié par corrélation d'image ou suivi de particules fluorescentes. A l'échelle moléculaire il sera aussi possible de s'orienter vers l'utilisation de molécules mécanophores, technique déjà appliquée avec succès au sein du laboratoire pour détecter les forces agissant sur les molécules et les ruptures de liaisons
This projects is part of an ambitious global project, which objective is to understand the mechanisms of fracture propagation in a soft material. The materials used during this PhD will mostly be hydrogels, whether with simple or double reticulation (chemical and physical). The introduction of dynamic (physical) bonds allows te delaying of the breaking of covalent (chemical) bonds, and increases the energy of failure. To this day, no model exists that would allow fracture prediction from the molecular structure. The objective of this project is thus to combine different technics to detect breaking at different scales. At macroscopic level, the speed of the fracture propagation and its triggering conditions will be studied. At the mesoscopic scale, the strain field at the fracture tip will be studied by digital image correlation or by the use of fluorescent particles. At the molecular scale, one possibility will be to use mecanophorous molecules, a technique already applied with success within the laboratory to detect the forces acting on molecules and bond breakings

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Cheikh, Fatma. "Identification de fractures dans un milieu poreux." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066417/document.

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Cette thèse est consacrée à l'étude mathématique d'un problème inverse en hydrogéologie : le but est d'identifier des fractures en milieu poreux, connaissant des mesures de l'écoulement dans le sous-sol. Le nombre, la localisation et les paramètres physiques des fractures sont recherchés. Ce problème est formulé comme la minimisation au sens des moindres carrés d'une fonctionnelle évaluant l'écart entre les mesures et les résultats du modèle direct. L'écoulement est celui d'un fluide monophasique incompressible (loi de Darcy). Un modèle traitant les fractures comme des interfaces est utilisé. Le problème direct est le modèle de fracture discrétisé par la méthode des éléments finis mixtes hybrides.Pour résoudre ce problème inverse, un nouvel algorithme itératif a été développé, basé sur l’utilisation d’indicateurs de fractures mis au point pendant la thèse. Ces indicateurs donnent une information au premier ordre concernant l'effet de l'ajout d'une nouvelle fracture. Comme ces indicateurs sont peu coûteux, un grand nombre de configurations de fractures sont testées à chaque itération. L’algorithme a été programmé, validé puis testé numériquement dans des situations variées, en utilisant des mesures synthétiques. Il donne des résultats très satisfaisants, bien que ce problème soit réputé difficile.Enfin, l’étude de l’identifiabilité du problème inverse a été amorcée. Pour un modèle simplifié de fractures (failles très perméables, cas le plus courant dans le sous-sol), on a montré que le problème
This PhD is dedicated to the mathematical study of an inverse problem in hydrogeology: the goal is to identify fractures in porous medium, knowing measurements of the underground flow. The number, the location and the physical parameters of the fracture are looked for. This problem is formulated as the least squares minimization of a function evaluating the misfit between measurements and the result of the direct model. We used a model describing the flow of a monophasic incompressible fluid (Darcy's law), in a porous medium containing some fractures represented by interfaces. The direct problem is the fracture model discretized by the mixed hybrid finite element method. To solve this inverse problem, we developed an iterative algorithm, which is based on the use of fracture indicators that have been developed durig the thesis. These indicators give a first order information concerning the effect of the addition of a new fracture. As these indicators are inexpensive, a large number of configurations of new fractures is tested at each iteration. The algorithm was programmed, validated and tested numerically in various situations, using synthetic measurements. It gives very satisfactory results, although this problem is considered difficult. Finally, an early study of identifiability of the inverse problem of fractures in porous medium has been achieved. It allowed to prove the identifiability for a simplified model (very permeable faults, which is common in the underground). The question of identifiability for the full fracture model remains open

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Cai, Zuansi. "Zero-valent iron fracture reactive barriers for remediating chlorinated solvent contaminants in fractured aquifers." Thesis, University of Sheffield, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425566.

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36

Ben-Yamin, Robert. "Les fractures de l'odontoïde : pronostic et traitement, une étude clinique portant sur 71 cas." Bordeaux 2, 1989. http://www.theses.fr/1989BOR25188.

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37

Dupoirieux, Laurent. "Etude critique du traitement des fractures de la mandibule : revue d'une série homogène sur trois ans." Montpellier 1, 1989. http://www.theses.fr/1989MON11161.

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38

Megy, Bernard. "Les fractures de l'extrémité inférieure du fémur : à propos de 139 observations : résultat fonctionnel et séquelles." Montpellier 1, 1988. http://www.theses.fr/1988MON11093.

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39

Martin, Bruno. "Les fractures de l'extrémité inférieure du fémur : à propos de 139 cas : étude générale et proposition d'une stratégie thérapeutique." Montpellier 1, 1988. http://www.theses.fr/1988MON11092.

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40

Garin, Christophe. "Attitude thérapeutique actuelle dans les fractures de la portion non dentée de la mandibule : à propos de 1157 cas." Bordeaux 2, 1991. http://www.theses.fr/1991BOR2M125.

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41

Oates, William Sumner. "Fracture of Ferroelectric Materials." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4769.

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Ferroelectric materials continue to find increasing use in actuator, sensor and transducer design. Questions regarding lifetime and reliability remain a concern due to the inherent low fracture toughness and complex material behavior. The poling procedure required for use in actuator and sensing devices introduces anisotropy in elastic and dielectric coefficients as well as piezoelectric coupling between the mechanical and electrical fields. This introduces complex fracture behavior which necessitates advanced analytical techniques and fracture characterization. In this dissertation, fracture mechanics of ferroelectric materials is evaluated by employing different analytical techniques and experimental methodology. The theoretical work has focused on linear piezoelectric coupling that accounts for the influence of anisotropy and heterogeneity on fracture. A new orthotropic rescaling technique is presented that explicitly solves the anisotropic linear elastic piezoelectric crack problem in terms of material coefficients. The effects of heterogeneities on electric field induced microfracture are analyzed by implementing a crack at the edge of a heterogeneous piezoelectric inclusion. A positive, flaw-localized driving force is realized when permeable crack face boundary conditions are considered. The experimental portion of the work evaluates fracture behavior in the ferroelectric ceramic, lead zirconate titanate (PZT), and the ferroelectric relaxor single crystal PZN-4.5%PT. Relative humidity and electric boundary conditions are shown to have significant effects on crack kinetics in PZT. Fracture anisotropy in single crystal PZN-4.5%PT is characterized using the Single-Edge V-notch Beam (SEVNB) method and Vickers indentations. Scanning electron micrographs are used to determine the crack profile which leads to a prediction of crack tip toughness and local energy release rate. A weak cleavage plane is identified in the single crystal relaxor which contains a significantly lower toughness in comparison to the ferroelectric ceramic PZT.

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42

Johansson-Evegård, Erik. "Artist Friendly Fracture Modelling." Thesis, Linköpings universitet, Institutionen för teknik och naturvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-74477.

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Destruction is one of the key aspects of visual effects. This report describes the work that was done to create a production ready pre-fracture modelling plug-in for Maya. It provides information on what methods that can be used to create a robust plug-in and various techniques for sampling points to create interesting fracture patterns using the Voronoi diagram. It also discusses how this work can be further built on to create an even better plug-in.

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43

Beh, Henry 1970. "Fracture of ductile polymers." Monash University, School of Physics and Materials Engineering, 2001. http://arrow.monash.edu.au/hdl/1959.1/9208.

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44

Cree, Marilyn Wanda. "Outcome following hip fracture." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0024/NQ34752.pdf.

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Khoo, Heng Aik. "Ductile fracture of steel." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0014/NQ59610.pdf.

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46

von, Rosen Michael. "Modelling of bolt fracture." Thesis, Linköpings universitet, Hållfasthetslära, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-107892.

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Computer simulations are widely used in the truck industry in order to provide assistance in the product development. Bolt joints are common in trucks. A bolt fracture usually has a great influence on how a truck structure will behave in a crash. Therefore, when simulating truck crashes it is important to be able to predict when bolt fracture occurs. A material model for 10.9 bolts has been calibrated and validated by using the finite element software LS-DYNA. The material model consists of a failure strain surface, which depends on the triaxiality, Lode parameter and the element size. In this thesis, the calibrated material model is referred to as the bolt model. A good agreement to predict the force at fracture in bolts between simulation model results and physical test results has been obtained. Still, further validation is needed to evaluate the bolt model completely.

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47

Greenfield, Diana. "Risk factors for fracture." Thesis, University of Sheffield, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301599.

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48

Thrusabanjong, Ekachai. "Fracture at bimaterial interfaces." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/46771.

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49

Teng, Xiaoqing. "High velocity impact fracture." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32118.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2005.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 315-330).
An in-depth understanding of dynamic ductile fracture is one of the most important steps to improve the survivability of critical structures such as the lost Twin Towers. In the present thesis, the macroscopic fracture modes and the fracture mechanisms of ductile structural components under high velocity impact are investigated numerically and theoretically. Attention is focused on the formation and propagation of through-thickness cracks, which is difficult to experimentally track down using currently available instruments. Studied are three typical and challenging types of impact problems: (i) rigid mass-to beam impact, (ii) the Taylor test, and (iii) dynamic compression tests on an axisymmetric hat specimen. Using an existing finite element code (ABAQUS/Explicit) implemented with the newly developed Bao-Wierzbicki's (BW) fracture criterion, a number of distinct failure modes including fragmentation, shear plugging, tensile tearing in rigid mass-to-beam impact, confined fracture, petalling, and shear cracking in the Taylor test, are successfully recreated for the first time in the open literature. All of the present predictions are in qualitative agreement with experimental observations.
(cont.) This investigation convincingly demonstrates the applicability of the BW's fracture criterion to high velocity impact problems and at the same time provides an insight into deficiencies of existing fracture loci. Besides void growth, the adiabatic shear banding is another basic failure mechanism often encountered in high velocity impact. This failure mechanism and subsequent fracture is studied through numerical simulation of a recently conducted compression test on a hat specimen. The periodical occurrence of hot spots in the propagating adiabatic shear bands is successfully captured. The relation between hot spots and crack formation is revealed. The numerical predictions correlate well with experimental results. An explicit expression controlling through-thickness crack growth is proposed and verified by performing an extensive parametric study in a wide range of input variables. Using this expression, a two-stage analytical model is formulated for shear plugging of a beam/plate impacted by a flat-nosed projectile. Obtained theoretical solutions are compared with experimental results published in the literature showing very good agreement.
(cont.) Three theoretical models for rigid mass-to-beam impact, the single, double, and multiple impact of beam-to-beam are derived from the momentum conservation principle. The obtained closed-form solutions, which are applicable to the axial stretching dominated case, are validated by finite element analysis.
by Xiaoqing Teng.
Ph.D.

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Gupta, Vijay 1962. "Problems in interface fracture." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/13975.

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