Dissertations / Theses: 'TENSILE PROPERTIES'

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Vega, Jens FernaÌndez. "Tensile properties of heat damaged concrete." Thesis, University of Sheffield, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247003.

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Brad, Rhodri. "The tensile properties of polymeric liquids." Thesis, Swansea University, 2008. https://cronfa.swan.ac.uk/Record/cronfa42332.

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The work reported in this Thesis reports on studies of the tensile strength of polymeric liquids by two experimental techniques, namely the Bullet-Piston (B-P) technique and a Capillary Break-up Extensional Rheometer (CaBER). The motivation for this work lies in the fact that although many associations exist between the cavitation properties of fluids and their extensional flow properties, these associations have never been systematically investigated due to a lack of an appropriate cavitation technique. The work presented m this thesis addresses this, using two custom-built instruments (a filament stretching device and a dynamic stressing technique for cavitation studies). Together, these were used to investigate the appropriate rheological and cavitational characteristics of a range of fluids including model polymer solutions. In experiments in which samples of degassed, deionised water are subjected to dynamic stressing by pulses of tension, the pulse reflection technique allows the rate of development of tension in the liquid, Of, to be varied m a systematic manner, in order to investigate its influence on the resulting measurement of the liquid's 'effective' tensile strength, Fc. Results are reported for a range of stressing rates, Of, ≈ 0.19bar/mus < Of < 0.77bar/mus. These experiments, which are the first of their kind to be reported on water, show an approximately four-fold increase of Fc at the highest stressing rate, this value being 224bar (for Of= 0.77bar/mus) compared to 59bar (for Of= 0.187bar/mus). The present work has resolved a longstanding anomaly concerning the role of polymeric additives in determining the cavitation thresholds of dilute aqueous polymer solutions. For the first time it is shown that with increasing molecular weight there is an increased effective tensile strength of the solution. However, the results reveal that increasing polymer concentration results in a stress saturation level in terms of effective tensile strength. This work is also the first to relate cavitational failure of a fluid and its extensional properties in terms of two appropriately chosen stress parameters, and to report the relationship between these stress parameters on the basis of an experimental study involving two different techniques over a range of stress rates and a wide range of polymer concentration and molecular weight. Despite differences in the magnitudes of the tensile stress parameters, both techniques show that the relevant parameter increases with polymer concentration and molecular weight, but that such stress levels become effectively saturated at essentially the same levels of concentration and molecular weight. This information has never previously been available. As a result of the work reported m this thesis it may now be possible to conduct fluid breakup measurements in extensional flow experiments m order to ascertain the likely levels of cavitation threshold stress for dilute aqueous polymer solutions.

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Adewole, Kazeem Kayode. "Effects of defects and reverse bending on tensile properties of tensile armour wires." Thesis, University of Newcastle Upon Tyne, 2011. http://hdl.handle.net/10443/1450.

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Flexible pipes are used for risers and flowlines in the offshore oil and gas industry and in many other applications. As part of the construction of these pipes, tensile armour wires are incorporated to resist longitudinal stresses which arise during installation and service. Tensile armour wires also resist hoop stresses for pipes without a designated pressure armour layer. The flexible pipeline manufacturing industry desires a better understanding of the tensile armour wire fracture mechanism, and especially the effects of defects with dimensions less than 0.2mm. Reverse bending operations (which arise due to the wire moving through paired rollers on unreeling during pipe manufacture) also affect the tensile properties of the tensile armour wires. Customarily, engineers estimate the safe load carrying capacity of defective wires solely by multiplying the ultimate strength obtained from a tension test by the original nominal area of the wire without any consideration for the fracture mechanisms of the wire. This approach may overestimate the strength of the wire. Recent research considering the fracture mechanisms of wires has employed a classical fracture mechanics approach, mainly using Linear Elastic Fracture Mechanics (LEFM) and/or Net Section Theory (NST). Obtaining parameters for fracture mechanics analyses requires large/thick standard fracture mechanics test specimens which cannot be made out of tensile armour wires due to their small size. Also fracture mechanics analyses based on these parameters including the elastic plastic crack opening displacement (COD) and J-integral parameters are largely size and geometry dependent making transferability of the results obtained from full size specimens to actual structures questionable. Laboratory tensile testing and tensile testing finite element simulations with mechanism-based fracture mechanics carried out on the as-received tensile armour wire and tensile armour wires with engineered defects reveal that the tensile armour wires fail by a shear mechanism. They also reveal that flat bottom scratches, pointed end scratches and dents identified from the Scanning Electron Microscope images of the as-received wire surface reduce the ultimate load and extension at fracture of the wires. In addition, denting was found to increase the wires yield load while scratching reduced the wire‟s yield load. The reduction in the tensile/ mechanical properties of tensile armour wires were found to depend largely on defect dimensions rather than defect locations with defects less than 0.2mm in any of its dimensions causing less than 0.072%, 0.238% and 10.946% reduction the yield load, the ultimate load and the displacement at fracture of tensile armour wires respectively. Laboratory and finite element simulations of reverse bending, straightening and tensile testing of the reverse bent tensile armour wires reveal that reverse bending and straightening operations reduce the ultimate load and fracture displacement of the wires. This work also reveals that the reverse bending process can only reveal near surface laminations as wires with mid depth laminations or with scratches less than 1mm deep would pass through the reverse bending process without fracturing.

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Wetter, Pernilla, and Martin Kulig. "Hållfasthetsegenskaper i gjutjärn : tensile properties of cast iron." Thesis, Jönköping University, JTH, Mechanical Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-931.

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In the last few years people have become more and more aware of how humanity is affecting the climate. In the direction of reducing the greenhouse gases is to design engines with higher tensile properties and reduced weight, in order to achieve lower fuel consumption and cleaner fuel incineration in today's truck engines.

In order to achieve these requirements it’s necessary to increase the combustion pressure in the engine. This requires higher tensile properties and high thermal conductivity of the engine material. The department of Component Technology at the University of Jönköping in collaboration with Volvo Powertrain AB, Scania CV AB and DAROS Piston Rings AB has been commissioned to develop this material and to find knowledge of material properties used in truck engines and piston rings used for marine applications.

The purpose with this work is to analyze the tensile properties of a series of cast iron, cast under different metallurgical conditions.

Four different series of cast irons have been analyzed from four points of view, carbon concentration, nodularity, amount inoculation and cooling rate.

After the tensile test all specimen data was analyzed in a mathematic calculation program called Matlab 2006a. These results were plotted in different diagrams to show the relations between the variables.

A low carbon contents and high cooling rate result in high tensile properties and vice versa. Also, a high nodularity gives the same result, i.e. high ultimate tensile strength, yield strength and young’s modulus. The experiment which cover different amount of inoculation, shows that Superseed is the most efficient element to increased tensile properties followed by Fe-powder and Fe-C-powder.

Lamellar graphite iron has the highest thermal conductivity and vibration damping properties compared to compact graphite iron followed by nodular graphite iron. Researches show that the thermal conductivity increases with slow cooling rate, irrespective of graphite structure. When designing new diesel engines, high tensile properties as well as high thermal conductivity are wanted. Compact cast iron has a compromised quality of these requirements. Higher tensile properties are a higher priority than thermal conductivity when the casting cooling rate is chosen.

Mänskligheten har idag blivit allt mer medveten om vilken påverkan människan har på klimatet. Ett steg i att reducera växthusgaserna är att konstruera motorer med högre hållfasthet och reducerad vikt, detta för att uppnå lägre bränsleförbrukning och renare förbränning i dagens lastbilsmotorer.

För att uppnå dessa krav är en lösning att öka kompressionen i motorn. Detta medför högre hållfasthetskrav samt hög värmeledningsförmåga hos materialet i motorerna. Avdelningen för komponentteknologi på Tekniska högskolan i Jönköping har i samarbete med Volvo Powertrain AB, Scania CV AB och DAROS Piston Rings AB fått uppdraget att utveckla ett material med rätt mekaniska egenskaper för att passa i lastbilsmotorer och kolvringar i marina applikationer.

Målet med detta examensarbete är att analysera de mekaniska egenskaperna i en serie där gjutjärn gjutets under olika metallurgiska förhållanden.

Fyra olika serier av gjutjärn har analyserats med utgångspunkt av variation av kolhalt, nodularitet, mängd ympningsmedel samt svalningshastighet.

Efter dragning av samtliga prover analyserades mätdata i Matlab 2006a och resulterade i olika sambandsdiagram.

Låg kolhalt samt snabb avsvalning av gjutgodset ger höga hållfasthetsegenskaper och vice versa. En hög nodularitet ger höga hållfasthetsegenskaper gällande brottgrans, sträckgräns och elasticitetsmodulmodul. Från experimenten där olika ympningsmedels påverkan av hållfastheten, har kunnat konstateras att ympningsmedlet Superseed ger de högsta hållfasthetsegenskaperna följt av Fe-pulver och Fe-C-pulver.

Värmeledningsförmågan och dämpningsförmågan för vibrationer är bäst i lamellartad grafit följt av kompakt och nodulär grafit. Studier visar att värmeledningsförmågan ökar med långsam svalning, oavsett grafitstruktur. I dagens dieselmotorer eftersträvas både god hållfasthet och god värmeledningsförmåga. En kompromiss av dessa krav är gjutjärn med en kompakt grafitstruktur. Högre hållfasthet bör prioriteras före bättre värmeledningsförmåga när val av svalningshastighet för gjutgodset görs.

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Marangou, Maria G. "Thermoforming of polystyrene sheets deformation and tensile properties." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65953.

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Miller, Zachary Dalton. "Tensile Properties of Single Vaginal Smooth Muscle Cells." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/83567.

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Improving treatment and prevention of pelvic organ prolapse, a disorder affecting up to half of parous women, requires thorough mechanical analysis of the vagina and other endopelvic structures at the cellular level. In this study, we tested single vaginal smooth muscle cells (SMCs) to quantify their elastic moduli. Cells were enzymatically isolated from vaginal walls of freshly sacrificed, virgin Long Evans rats and cultured using well-established methods. A custom-built experimental setup was used to perform tensile tests. Micropipettes were fabricated to serve as cantilever-type load cells, which were coated in cellular adhesive. Two pipettes applied tension to SMCs until adhesion between the cell and a pipette failed. During mechanical testing, images of SMCs were collected and translated into strain and stress. Specifically, force/stress data were calculated using Euler-Bernoulli Beam Theory and by making simplifying geometric assumptions. The average initial and total elastic moduli (mean ± SEM) for single vaginal SMCs were 6.06 ± 0.26 kPa and 5.4 ± 0.24 kPa, respectively, which is within the range reported for other types of SMCs, mainly airway and vascular, of various species. This protocol can and will be applied to further investigate mechanics of single cells from the pelvic region with independent variables such as parity, age, body mass index, and various stages of POP. Results of these experiments will provide critical information for improving current treatments like drug therapies, surgical procedures, medical grafts and implants, and preventative practices like stretching and exercise techniques.
Master of Science

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Shao, Xin. "Theoretical modeling of the tensile behavior of staple yarn." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/8273.

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Schleifenbaum, Stefan, Torsten Prietzel, Gabriela Aust, Andreas Boldt, Sebastian Fritsch, Isabel Keil, Holger Koch, et al. "Acellularization-induced changes in tensile properties are organ specific." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-204096.

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Introduction: Though xenogeneic acellular scaffolds are frequently used for surgical reconstruction, knowledge of their mechanical properties is lacking. This study compared the mechanical, histological and ultrastructural properties of various native and acellular specimens. Materials and methods: Porcine esophagi, ureters and skin were tested mechanically in a native or acellular condition, focusing on the elastic modulus, ultimate tensile stress and maximum strain. The testing protocol for soft tissues was standardized, including the adaption of the tissue’s water content and partial plastination to minimize material slippage as well as templates for normed sample dimensions and precise cross-section measurements. The native and acellular tissues were compared at the microscopic and ultrastructural level with a focus on type I collagens. Results: Increased elastic modulus and ultimate tensile stress values were quantified in acellular esophagi and ureters compared to the native condition. In contrast, these values were strongly decreased in the skin after acellularization. Acellularization-related decreases in maximum strain were found in all tissues. Type I collagens were well-preserved in these samples; however, clotting and a loss of cross-linking type I collagens was observed ultrastructurally. Elastins and fibronectins were preserved in the esophagi and ureters. A loss of the epidermal layer and decreased fibronectin content was present in the skin. Discussion: Acellularization induces changes in the tensile properties of soft tissues. Some of these changes appear to be organ specific. Loss of cross-linking type I collagen may indicate increased mechanical strength due to decreasing transverse forces acting upon the scaffolds, whereas fibronectin loss may be related to decreased load-bearing capacity. Potentially, the alterations in tissue mechanics are linked to organ function and to the interplay of cells and the extracellular matrix, which is different in hollow organs when compared to skin.

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Whitley, Karen Suzanne. "Tensile and Compressive Mechanical Behavior of IM7/PETI-5 at Cryogenic Temperatures." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/35944.

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In order for future space transportation vehicles to be considered economically viable, the extensive use of lightweight materials is critical. For spacecraft with liquid fueled rocket engines, one area identified as a potential source for significant weight reduction is the replacement of traditional metallic cryogenic fuel tanks with newer designs based on polymer matrix composites. For long-term applications such as those dictated by manned, reusable launch vehicles, an efficient cryo-tank design must ensure a safe and reliable operating environment. To execute this design, extensive experimental data must be collected on the lifetime durability of PMC's subjected to realistic thermal and mechanical environments. However, since polymer matrix composites (PMC's) have seen limited use as structural materials in the extreme environment of cryogenic tanks, the available literature provides few sources of experimental data on the strength, stiffness, and durability of PMC's operating at cryogenic temperatures.

It is recognized that a broad spectrum of factors influence the mechanical properties of PMC's including material selection, composite fabrication and handling, aging or preconditioning, specimen preparation, laminate ply lay-up, and test procedures. It is the intent of this thesis to investigate and report performance of PMC's in cryogenic environments by providing analysis of results from experimental data developed from a series of thermal/mechanical tests. The selected test conditions represented a range of exposure times, loads and temperatures similar to those experienced during the lifetime of a cryogenic, hydrogen fuel tank. Fundamental, lamina-level material properties along with properties of typical design laminates were measured, analyzed, and correlated against test environments. Material stiffness, strength, and damage, will be given as a function of both cryogenic test temperatures and pre-test cryogenic aging conditions.

This study focused on test temperature, preconditioning methods, and laminate configuration as the primary test variables. The material used in the study, (IM7/PETI-5), is an advanced carbon fiber, thermoplastic polyimide composite.
Master of Science

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Hagman, Anton. "Influence of inhomogeneities on the tensile and compressive mechanical properties of paperboard." Doctoral thesis, KTH, Hållfasthetslära (Avd.), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-185917.

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The in-plane properties of paperboard have always been of interest to paper scientists. Tensile properties are crucial when the board is fed through converting machines at high speeds. Compressive properties are essential in the later use. Inhomogeneities affect both the compressive and tensile properties. For the tensile properties, it is the inherent heterogeneity of the paperboard that might cause problems for the board-maker. Varying material properties, through the thickness of the paperboard, are on the other hand used to achieve high bending stiffness with low fiber usage. It is of interest to know how this practice affects the local compressive properties. Papers A and B aims to address this, while C, D and E focus on in-plane heterogeneities. Paper A investigates the mechanism that causes failure in the short span compression test (SCT). It was concluded that the main mechanism for failure in SCT is delamination due to shear damage. In paper B the effect of the through-thickness profiles on the local compression strength was examined. It was concluded that the local compression is governed by in-plane stiffness and through thickness delamination. The latter was in turn dependent on the local shear strength and in-plane stiffness gradients. In paper C the tensile test is investigated with focus on sample size and strain distributions. The strain behavior was dependent on the length to width ratio of the sample and was caused by activation of local zones with high strainability. Paper D focuses on the strain zones seen in C. The thermal response in paper was studied. It was observed that an inhomogeneous deformation pattern arose in the paper samples during tensile testing. It was concluded that the heat patterns observed coincided with the deformation patterns. It could be shown that the formation was the cause of the inhomogeneous deformation. In final paper, E, the virtual field method was applied on data from C.
Egenskaperna hos ett kartongark kan grovt delas upp i två kategorier: i-planet egenskaper och ut-ur-planet egenskaper. I-planet egenskaperna har länge varit ett område som pappersmekanister och andra pappersforskare visat intresse för. Anledningen till detta är att de är avgörande för hur väl det går att konvertera kartongen till färdiga förpackningar, samt hur väl de förpackningarna klarar sin uppgift. Dragegenskaperna prövas när kartongen dras genom tryck- och konverteringsmaskiner i hög hastighet. Tryckegenskaperna spelar stor roll för hur väl en förpackning klarar att staplas och hålla sitt innehåll intakt. Inhomogeniteter påverkar både drag och tryckegenskaper. Papprets naturliga variation påverkar dragegenskaperna hos kartongen och kan orsaka problem för kartongmakarna. Särskilt när utvecklingen går mot mer avancerade kartong utseenden. Å andra sidan så använder sig kartongmakare flitigt av egenskapsvariationer genom tjockleken på kartongen, när dom vill åstadkomma böjstyva kartonger utan att slösa med fibrer. I detta fall är det intressant att veta hur de lokala kompressionsegenskaperna påverkas av kartongens ut-ur-planet profil. Det första två uppsatserna i denna avhandling, A och B, handlar om just detta. Uppsatserna C, D och E avhandlar hur i-planet variationer påverkar kartongens egenskaper. I Artikel A undersöks vilka skademekanismer som aktiveras under ett kortspannskompressionstest (SCT). Tre flerskiktskartonger undersöktes. De hade valts så att de hade distinkt olika skjuvstyrkeprofiler. Kartongerna karakteriserades och datan användes som materialdata i en finit element modell av SCT-testet. Modellen bestod av skikt, betraktade som kontinuum, mellan vilka det fanns kohesiva ytor. Huvudmekanismen i SCT var att kartongen delaminerade på grund av skjuvskador. Den andra uppsatsen, Artikel B, var en fortsättning på den första. Denna gång undersöktes fem flerskiktskartonger framtagna så att de hade olika skjuvstyrka beroende på positionen i tjockleksled. Det konstaterades att kompressionsegenskaperna lokalt styrs av skjuvstyrkeprofilen och styvhetsgradienter. Vidare konstaterades det att mekanismerna innan kartongen delaminerar är, i huvudsak, elastiska. Den tredje artikeln, Artikel C, fokuserade på hur dragprov på kartong påverkas av provstorleken och töjningsvariationen. Tre olika flerskiktskartonger användes som provmaterial och provbitar med olika storlek analyserades. Förutom dragprov så användes digital image correlation (DIC) för analysen. Det visade sig att den globala töjbarheten varierade med storleken på provet beroende på kvoten mellan längd och bredd. DIC visade att detta i sin tur berodde på att zoner med hög töjbarhet aktiverades i provet. Dessa zoner hade samma storlek oberoende av provstorlek och påverkade därför den totala töjbarheten olika mycket. Artikel D undersöker töjningszonerna som sågs i Artikel C samt hur de påverkas av kreppning. Vidare undersöktes pappersproverna med hjälp av termografi. Termografin visade att varma zoner uppstod i proven när det töjdes. Zonerna blev synliga när provet töjdes plastiskt. Termografi kördes parallellt med DIC på några prover. Det visade sig att de varma zonerna överenstämde med zoner med hög lokal töjning. Vidare kunde det visas att dessa zoner övenstämde med papperets mikrostruktur, formationen. En finit element analys av hur papper med olika formation töjs gjordes. Delar av provningen gjordes på kreppade papper som har högre töjbarhet. Det visades sig att någon form av skada hade överlagrats på papprets mikrostruktur under kreppningen, och att den deformationen återtogs när pappret töjdes. I den sista artikeln, Artikel E, behandlas hur VFM (Virtual Field Method) kan användas på DIC-data från kartong. DIC-datan som användes hämtades från Artikel C. Detta gjordes för att visa på hur olika VFM-formuleringar kan användas för att karakterisera styvhetsvariationen hos kartong. Provet delades upp i tre subregioner baserat på den axiella töjningsgraden. VFM-analysen visade att dessa subregioners styvhet och tvärkontraktionstal sjönk monotont, men att skillnaden mellan regionerna ökade med ökande spänning. även om endast ett prov undersöktes, så indikerade resultaten att områden med hög styvhet endast förbättrar de mekaniska egenskaperna marginellt. Analysen visade också att även om subregionerna inte är sammanhängande, så har dom liknande mekaniska egenskaper.

QC 20160429

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Dean, Joseph Youle Lee. "Assessment of material properties of tension membrane fabrics." Thesis, Queensland University of Technology, 1994. https://eprints.qut.edu.au/35996/1/35996_Dean_1994.pdf.

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Tension membrane structures in the form of tents and ship sails date from man's earliest origins. In recent times membranes are used in larger and more permanent applications. The development of the science of tensioned membrane structures is discussed briefly. Modern material types and design methods are discussed. Elements of good patterning are discussed and supported by finite element sensitivity study. Ideal fabric material properties for serviceable structures are listed. The property of primary focus for the testing undertaken is ultimate biaxial strength. Young's moduli, Poisson's ratios and shear modulus are also properties of interest which are dealt with briefly. Styles of biaxial testing are discussed. A cylindrical biaxial tester has been designed and constructed and a proving testing program conducted. Methods of extraction of material properties from loading data are discussed.

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Young, Christina R. T. "Measurement of the biaxial tensile properties of paintings on canvas." Thesis, Imperial College London, 1996. http://hdl.handle.net/10044/1/7965.

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McRay, Nelson. "Simplified supersaturation effects on the tensile properties of A357 alloys." Thesis, Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/15948.

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Willcock, Simon Nicolas Murray. "An investigation of the magnetic properties of high tensile steels." Thesis, Durham University, 1985. http://etheses.dur.ac.uk/7026/.

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This thesis describes an investigation of the magnetic properties of high tensile steels typical of those produced for the high pressure gas pipe-line industry. Results are presented for both bulk and small section samples, and the observed variations in magnetic behaviour as a function of orientation and position within the steel are described qualitatively by changes in steel metallography. The development of an automated double-crank Vibrating Sample Magnetometer, required for determining the magnetic characteristics of small samples, is also described which, without signal amplification, has a moment detectability limit of 10(^-4) e.m.u. The representation of the full magnetization loop by a Fourier series is investigated and the variations in harmonic amplitudes found for the range of steels considered here are compared to those predicted by theoretical models. The successful parameterization of the initial magnetization curve is also reported using a two parameter model (LnB = (k – H(^-1))LnA)), and linear relationships between the coercive field (H(_c)) and these parameters (k,LnA) are presented which permit the prediction of the initial magnetization curve of any similar steel from a knowledge of H(_c). Although the latter may be determined accurately by direct measurements of small samples, further linear relationships are indicated which allow the determination of the coercive field from knowledge of either the steel chemistry or metallography. The compatibility of the observed ferrite grain size dependent contribution to the coercive field with grain boundary domain wall pinning models is also investigated.

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Wilkins, Robert Douglas. "Tensile properties of fibrocartilage from the human knee joint meniscus." Thesis, The University of Sydney, 1990. https://hdl.handle.net/2123/26303.

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The mechanical function of the human knee joint meniscus is not yet well understood. While the tissue has previously been regarded as superfluous. recent research suggests that it may perform an important mechanical role in the healthy joint, and should be preserved or repaired where possible. In an effort to contribute to the understanding of this tissue, tensile tests have been performed on small specimens from the meniscus under a range of conditions to provide more information on the tissue function. The use of uni-axial tensile tests is based on the concept of the meniscus as a compressed tissue developing circumferential tension in its outer region to withstand the applied loading of a normal physiological joint. Circumferentially aligned collagen fibres withstand this tension and retain the meniscis in the joint cavity. where its assumed primary function is to increase the weight bearing interface, thereby reducing joint stresses. New methods and apparatus have been developed for the tensile testing of micro specimens from the meniscus under a range of controlled conditions. While many of the imposed testing conditions are remote from normal physiological conditions, they have been carefully chosen to elucidate information concerning the contribution of various tissue components to the observed mechanical function of the tissue. New data are presented concerning the tissue response to cyclic extension, stress relaxation, refrigerated and frozen storage, chemically induced water uptake, chemical fixation, and hyaluronidase digestion. These results are discussed and interpreted in relation to the mechanical function of the meniscus in the normal weight bearing knee joint.

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Dippenaar, Jan Diederick. "The tensile properties of early age concrete and the experimental apparatus required for its determination." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/96866.

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Thesis (MEng)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: The early age cracking of concrete, which includes plastic shrinkage cracking (PShC) and plastic settlement cracking (PSeC), commonly occurs in flat concrete elements such as bridge decks and slabs or at the change of a concrete section depth. These cracks typically occur once the concrete has been cast and consolidated up to the final setting time, and initiate when the tensile stresses developed in the concrete exceeds its ultimate tensile strength or, alternatively phrased, when the restrained shrinkage induced strain in the concrete exceeds its tensile strain capacity. These cracks have a premature detrimental effect on the durability and strength of concrete structures as they allow deleterious materials to penetrate the concrete, which could cause the corrosion of steel reinforcing. With this in mind, the objective of this study is to gain a fundamental understanding of the tensile properties of early age concrete, up to the point of final setting, as well as the variables that affect these properties. This is done to better understand, and ultimately reduce the risk of early age cracking. To achieve this, experimental assemblies found in literature were evaluated and built upon to create a multi-component uniaxial tensile testing setup that is able to capture the complete stress-strain behaviour of early age concrete, while still in a plastic state. The following significant findings were attained from this study: • Reducing the coarse aggregate size in a concrete mix increases both the tensile strength and Young’s modulus of early age concrete, while reducing both its fracture energy and fracture process zone (FPZ) characteristic length. • The low volume addition of microfibres to a conventional concrete mix increases both the fracture energy and the FPZ characteristic length of early age concrete. • The low volume addition of microfibres to a conventional concrete mix increases the strain capacity of early age concrete shortly before and after the initial setting time. This increased strain capacity is believed to be of great significance for the prevention of PShC. • The addition of an accelerator to a conventional concrete mix accelerates the development of the tensile properties of early age concrete, while a retarder reduces it. • The addition of a retarder to a conventional concrete mix increases the strain capacity of early age concrete shortly before and after the initial setting time. This provides a reason for the reduced PShC severity observed in retarded mixes in certain instances. From this study it is concluded that the results from the tensile tests provide a greater understanding of the tensile properties of early age concrete as well as the variables that affect them. When interpreting these results in combination with those obtained from PShC experiments, it is suggested that it is possible to determine when and if PShC will occur.
AFRIKAANSE OPSOMMING: Die vroëe-ouderdom kraking van beton, wat plastiese krimp krake (PKK) en plastiese versakkings krake (PVK) insluit, kom algemeen voor in plat betonelemente soos brug-dekke en blaaie, of by die die verandering in die deursnit diepte van betonelemente. Die krake kom tiepies voor vandat beton gegiet en gekompakteer is totdat dit die finale settyd bereik, en vind plaas sodra die trekspanning wat in die beton ontstaan sy treksterkte oorskry of, anders bewoord, wanneer die verhinderde krimp geinduseerde vervorming van die beton, die vervormings-kapasiteit van die beton oorskry. Hierdie krake het ŉ voortydige nagelige uitwerking op die duursaamheid en sterkte van betonstrukture aangesien hulle toelaat dat skadelike stowwe die beton binnedring, wat die korrosie van staalbewapening veroorsaak. Met dit ingedagte is die doel van die studie om fundamentele kennis rakende die vroëe-ouderdom trekeienskappe van beton, tot by die punt van finale set, asook die veranderlikes wat die eienskappe beinvloed, te verwerf. Om vroëe-ouederdom krake beter te verstaan en uiteindelik, te voorkom, is hierdie kennis nodig. Eksperimentele opstellings in literatuur is ge-evalueer en op voortgebou vir die bou van ŉ multi-komponet eenassige terktoetsopstelling om die volledige spanning-vervorming gedrag van vroëe-ouderdom beton vas te vang. Die volgende bevindings het uit die studie aan die lig gekom: • ŉ Kleiner aggregaat grootte in n betonmeng verhoog beide die trekstrekte en Young se modulus van vroëe-ouderdom beton, terwyl dit beide die fraktuur-energie en die fraktuur proses sone (FPS) se karakteristieke lengte verminder. • Die lae volume byvoeging van mikrovesels tot ŉ betonmeng verhoog beide die fraktuur-energie en die FPS se karakteristieke lengte van vroëe-ouderdom beton. • Die lae volume byvoeging van mikrovesels tot ŉ betonmeng verhoog die vervormings kapasiteit van vroëe-ouderdom beton kort voor en na die aanvanklike settyd. Daar word geglo dat hierdie verhoogde vervormings-kapasiteit van groot belang is vir die voorkoming van PKK. • Die byvoeging van ŉ versneller tot ŉ betonmeng versnel die ontwikkelingstempo van die trekeienskappe van vroëe-ouderdom beton, terwyl ŉ vertrager dit verlaag. • Die byvoeging van ŉ vertrager tot ŉ betonmeng verhoog die vervormings-kapasiteit van vroëe-ouderdom beton kort voor en na die aanvanklike settyd. Dit verskaf die rede vir die bevinding dat die byvoeging van ŉ vertrager PKK in sekere gevalle verminder. Hierdie studie het bevind dat die die trektoetse ŉ groter begrip rakende die trek-eienskappe van vroëe-ouderdom beton, en die veranderlikes wat die eienskappe beinvloed, gelewer het. Wanneer die resultate van die studie tesame met PShC toetse geinterpreteer word, will dit voorkom dat dit moontlik is om te bepaal wanneer, en of PKK sal plaasvind.

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Kultikova, Elena V. "Structure and Properties Relationships of Densified Wood." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/35810.

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The objective of this research was to investigate the effect of applied compressive strain in various environments, on the strength and stiffness of compressed wood samples. It is believed that transverse compression of wood at specific conditions of temperature and moisture will result in improved mechanical properties, which can be attributed to increased density and perhaps other physical or chemical changes.

Specimens of both mature and juvenile southern pine (Pinus taeda) and yellow-poplar (Liriodendron tulipifera) were compressed radially at three different temperature, and moisture content conditions relevant to the glass transition of wood.

Ultimate tensile stress and longitudinal modulus of elasticity were obtained by testing compressed, uncompressed and control samples in tension parallel-to-grain. Strain measurements were performed using laboratory-built clip-on strain gauge transducers. Results of the tensile tests have shown an increase in the ultimate tensile stress and modulus of elasticity after all densification treatments.

Scanning electron microscopy was employed for observing changes in cellular structure of densified wood. Existence of the cell wall fractures was evaluated using image processing and analysis software. Changes in cellular structure were correlated with the results of the tensile test.

Chemical composition of wood samples before and after desorption experiments was determined by acid hydrolysis followed by high performance liquid chromatography (HPLC). The results of the chemical analysis of the wood specimens did not reveal significant changes in chemical composition of wood when subjected to 160 Â°C, pure steam for up to 8 hours.

The results of this research will provide information about modifications that occur during wood compression and will result in better understanding of material behavior during the manufacture of wood-based composites. In the long run, modification of wood with inadequate mechanical properties can have a significant effect on the wood products industry. Low density and juvenile wood can be used in new high-performance wood-based composite materials instead of old-growth timber.
Master of Science

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Sarzynski, Melanie Diane. "Carbon foam characterization: sandwich flexure, tensile and shear response." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/55.

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The focus of this research is characterizing a new material system composed of carbon and graphite foams, which has potential in a wide variety of applications encompassing aerospace, military, offshore, power production and other commercial industries. The benefits of this new material include low cost, light weight, fire-resistance, good energy absorption, and thermal insulation or conduction as desired. The objective of this research is to explore the bulk material properties and failure modes of the carbon foam through experimental and computational analysis in order to provide a better understanding and assessment of the material for successful design in future applications. Experiments are conducted according to ASTM standards to determine the mechanical properties and failure modes of the carbon foam. Sandwich beams composed of open cell carbon foam cores and carbon-epoxy laminate face sheets are tested in the flexure condition using a four point setup. The primary failure mode is shear cracks developing in the carbon foam core at a critical axial strain value of 2,262 με. In addition to flexure, the carbon foam is loaded under tensile and shear loads to determine the respective material moduli. Computational analysis is undertaken to further investigate the carbon foam's failure modes and material characteristics in the sandwich beam configuration. Initial estimates are found using classical laminated plate theory and a linear finite element model. Poor results were obtained due to violation of assumptions used in both cases. Thus, an additional computational analysis incorporating three dimensional strain-displacement relationships into the finite element analysis is used. Also, a failure behavior pattern for the carbon foam core is included to simulate the unique failure progression of the carbon foam on a microstructure level. Results indicate that displacements, strains and stresses from the flexure experiments are closely predicted by this two parameter progressive damage model. The final computational model consisted of a bond line (interface) study to determine the source of the damage initiation, and it is concluded that damage initiates in the carbon foam, not at the bond line.

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Sundblad, Sara. "Predictions of Pulp and Paper Properties Based on Fiber Morphology." Thesis, KTH, Skolan för kemivetenskap (CHE), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-180550.

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The aim is to investigate models that predicts the potential of pulp and evaluate the relevance of the zero-span tensile index within these. Two chemical pulps made from softwood and eucalyptus were refined in a Voith-beater with different energy input in order to study the change of fiber morphology signals and other pulp and paper properties. Chemical, THP pulp from Södra Värö is also used as an initial analysis for morphological connections to Zero-span tensile index. The L&W Fiber Tester Plus is used in order to study the pulps fiber morphology and Pulmac 2000 for zero span. Handsheets are made for mechanical tests such as tensile properties, ZD-strength and optical properties. Many of the given signals change according to clear patterns with increasing refining energy. Using least square methods, formulas describing the development with high adaptation could be formulated. Many of the measured aspects changes over already known patterns. These are then applied in the models. Three possible models is tested: linear regression, Shear-Lag and Page. Of the three, only the two first ones where able to produce reliable models, whereas the third required data that was difficult to acquire at the same time as the adaptation was very low. The only model that use exclusively morphology data is linear regression.

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Berry, Carolyn. "DESIGN AND DEVELOPMENT OF TWO TEST FIXTURES TO TEST THE LONGITUDINAL AND TRANSVERSE TENSILE PROPERTIES OF SMALL DIAMETER TUBULAR POLYMERS." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/494.

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Hundreds of thousands of vascular bypass grafts are implanted in the United States every year, but there has yet to be an ideal graft material to substitute for one’s own autologous vessel. Many synthetic materials have been shown to be successful vessel replacements; however, none have been proven to exhibit the same mechanical properties as native vessels, one of the most important criteria in selecting a vascular graft material. Part of this issue is due to the fact that, currently, there is no “gold standard” for testing the longitudinal and transverse tensile properties of small diameter tubular materials. While there are ASTM and ISO standards that suggest ways to test tubes in their original form, many researchers have published tensile strength data based on cutting the tube and testing it as a flat sample. Thus, it was the aim of this thesis to understand, establish, and implement accurate tensile testing methods of small diameter polymers in their original, tubular state on Cal Poly’s campus. Two test fixtures were created based on specified design criteria in order to test materials in their tubular form in both the longitudinal and transverse directions. Both fixtures were successful in testing PLGA and ePTFE samples, and statistical data was gathered for the transverse test fixture. The new transverse test fixture was tested against the current method of testing, and a significant (α = 0.05) difference between methods was established for ultimate tensile strength. This analysis, however, cannot determine which test method is more accurate, thus more extensive testing is required to verify the design of both fixtures. By developing a method for testing small diameter polymers in tubular form on Cal Poly’s campus, it allows for more testing of various small diameter tubes and more comparative data to validate each design. It also demonstrates a need for a more detailed and widespread standardization of testing for small diameter tubes, especially in vascular substitute applications where the ideal vessel replacement has yet to be found.

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Kalaugher, Elizabeth Mary. "The mechanical properties of CVD diamond coated fibres." Thesis, University of Bristol, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264062.

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Godfrey, Tanya Michelle Teresa. "Production, microstructure and tensile properties of mechanically milled titanium-boron alloys." Thesis, Imperial College London, 2001. http://hdl.handle.net/10044/1/12031.

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Cornwell, Hayden K. "Tensile and interfacial properties of radially aligned CNT grown carbon fibers." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/112417.

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Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2017.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 100-109).
The relatively high mass-specific strength and stiffness of carbon fibers (CFs) has established CF reinforced plastics (CFRPs) as the benchmark material for next-generation aerospace structures. While CFRPs with radially-grown aligned carbon nanotubes (CNTs), termed fuzzy fiber reinforced plastics (FFRPs), have exhibited enhanced inter- and intralaminar mechanical properties on model FRP systems, these results have not been replicated for aerospace-grade CFRP due to challenges in manufacturing. This thesis reports a scaled (weave- vs. tow-level) manufacturing method of fuzzy woven CFRPs designed to yield dense and aligned CNT coverage on the fibers, and retain the fiber tensile and interface properties. These challenges were explored through mechanical testing, in addition to numerical reactive computational fluid dynamics (CFD) CNT growth models. Single fiber tensile tests for fuzzy fibers from aerospace-grade CF weaves showed no reduction in tensile strength compared to baseline (as received) fibers. Continuously monitored single fiber composite fragmentation testing revealed a 34% decrease in fiber-matrix interfacial shear strength (IFSS) for sized (polymer coating on fibers) fuzzy fibers, attributed to thermally induced sizing transformations during CNT growth, whereas the fuzzy de-sized fibers exhibited no reduction in IFSS. The CFD model demonstrated gas depletion trends correlated to the areas of substandard growth and a high sensitivity to the surface-to-volume ratio of the porous woven substrate. Retained CF properties supports this facile, scaled manufacturing method's ability to disperse CNTs uniformly on CF weaves to create a laminate-level fuzzy CFRP towards enhanced mechanical and multifunctional properties. With continued CNT growth modeling efforts, further scaling of this fuzzy CFRP architecture could be integrated into commercial manufacturing processes.
by Hayden K. Cornwell.
S.M.

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Jones, Joy. "Neural network modelling of the tensile properties of Ni-base superalloys." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624649.

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Mohammad, Sophia Nishat. "Effect of storage on tensile properties of natural heart valve tissue." Thesis, University of Surrey, 1994. http://epubs.surrey.ac.uk/776190/.

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Aortic homograft valves are the preferred choice of replacement valve in aortic valve replacement procedures. The major drawback to their use is their availability. This project addressed two of the methods by which availability can be increased by assessing mechanical properties of the valves. Most pre-operative methods that assess homograft valve post-operative functional ability use biochemical or histological protocols. Rarely is their mechanical ability to sustain the pressure across them tested. Uniaxial tensile tests were performed on radial and circumferential leaflet sections from human and porcine aortic and pulmonary valves. The pulmonary valve has very similar anatomy to the aortic valve, although it is thinner and there is less pressure across it in vivo. When a patients own pulmonary valve is used to replace their aortic (their pulmonary valve is replaced with an aortic homograft), good post-operative results are achieved. The aim of this study was to see if pulmonary homografts would be able to sustain aortic pressures. It is concluded that pulmonary leaflet specimens have comparable mechanical characteristics to aortic and should therefore be suitable for aortic valve replacement. This would double the number of valves available for surgeons to use during valve replacements. Porcine aortic specimens were found to be stiffer and fail at higher stresses than the other valve types. The results from the porcine pulmonary specimen properties indicated that bioprosthetic valve manufacturers can consider their use in bioprosthetic valve manufacture as they are more than able to cope with human aortic valve pressures. Some storage methods have been assigned short duration or 'sell-by' dates, with no evidence that the mechanical integrity of the tissues has been significantly compromised. Currently retrospective studies are used to assess whether the treatments are detrimental to the tissues; the post-operative durability being taken as the indicator! If the storage times can be extended then the number of valves available to surgeons would increase. Four treatments of valves used for storage were tested over three months and their effect on leaflet specimen tensile properties determined. Glutaraldehyde had a significant effect on the tensile properties of the specimens and this suggests that alternative methods should be used to treat bioprosthetic valves, which are fixed in it. Treatment with antibiotics produced losses in stiffness of the tissues at three months, but these were within physiological limits. Therefore valves stored in this manner can be stored as long as three months at least with no effect on valve function in vivo. Cryopreservation with glycerol over three months produced less changes in specimen properties which again should not affect valve function in vivo. Cryopreservation with dimethyl sulphoxide (DMSO) caused the least difference in specimen properties compared to fresh tissues. It is therefore recommended as the first choice in valve treatments for storage. It is suggested that all new valve storage treatments be assessed for their mechanical effects on the tissues routinely. Preliminary work on a non-destructive intact valve test device using polarised light is introduced. This has potential for use in pre-operative assessment of valve mechanical integrity.

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Erdiller, Emrah Salim. "Experimental Investigation For Mechanical Properties Of Filament Wound Composite Tubes." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/3/12605140/index.pdf.

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The aim of this study is to investigate the mechanical properties of continuous fiber reinforced composite tubes, produced by filament winding technique. For this purpose, tensile and split-disk tests were performed with specimens produced with five different fiber materials and two different resin systems. Longitudinal tensile and hoop tensile properties of the selected specimens were determined and the effect of reinforcement direction on the mechanical performance of these composites was investigated. In addition, the effect of a filament-winding processing variable (fiber tension) on longitudinal and hoop tensile properties of the selected composites was obtained. A slight increase in hoop/longitudinal tensile properties of specimens was observed for specimens wounded with tension and with winding angles greater than 60o. The tests were performed according to American Society for Testing and Materials (ASTM) standards. The split-disk tests of selected composite specimens were simulated by the finite element method. For this purpose, a commercial finite element package program was used. Experimental results were used both as input in terms of material data for the finite element study and for comparison purposes. A good agreement was obtained between the simulation results and the experimental data.

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Frei, Katherine Rebecca. "Morphology Tuning and Mechanical Properties of Nanoporous Gold." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/91899.

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Nanoporous gold is an exciting topic that has been highly researched due to its potential in applications including sensing, catalysts, gas storage, and heat exchangers, made possible by its high surface area to volume ratio and high porosity. However, these applications tend to require a specific morphology, which is often difficult to control. In this work, significant strides have been made in tuning the morphology of nanoporous gold by studying the effect of different fabrication parameters on the ligament diameter, pore diameter, and ligament length, three characteristics which are most discussed in previous studies concerning nanoporous gold. This material also, generally shows a brittle behavior despite it consisting of a normally ductile constituent element, limiting many commercial applications. There have been multiple simulated studies on the tensile mechanical properties and the fracture mode of this material, but limited experimental tensile testing research exists due to technical difficulty of conducting such experiments with small fragile samples. We examine the tensile mechanical behavior of nanoporous gold with ligament sizes ranging from 10 to 30 nm using in situ tensile testing under an environmental scanning electron microscope (ESEM). A specially designed tensile stage and sample holders are used to deform the sample inside the ESEM, allowing us to observing both the macro and microscopic structure changes. Our experimental results advance our understandings of how porous structure influence the mechanical properties of nanoporous gold, and they also serve to increase the accuracy of future simulation studies that will take this material a step towards commercial use by providing a thorough understanding of its structural mechanical limitations.
MS

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Sabry, Mohammad Sabry Ismail. "The influence of specimen size on the measurement of mechanical properties of fabrics." Thesis, University of Leeds, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329211.

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Riestra, Perna Martin Ignacio. "TAILORING PROPERTIES TO REPRESENT HPDC TENSILE AND FATIGUE BEHAVIOUR IN ALUMINIUM-SILICON CAST ALLOY PROTOTYPES." Thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH. Forskningsmiljö Material och tillverkning – Gjutning, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-27734.

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The work presented aims to find alternatives for the prototyping of components by sand and plaster mold manufacturing processes that deliver properties similar to high pressure die casting (HPDC). Sand and plaster test samples have been casted. The Al-7Si-0.35Mg alloy has been tested in as cast condition and in a heat treated condition; T5 for sand cast samples and T6 for those plaster cast. The Al-7Si-2Cu-0.35Mg alloy was also tested in as cast condition. Tensile, fatigue and hardness tests have been performed. Microstructural investigation comprising secondary dendrite arm spacing, defects, Fe-rich β-phases and Si size measurements has been performed on the different conditions. The results have been compared to available data for Al-9Si-3Cu-(Fe) alloy used in HPDC. The T5 heat treated sand cast condition has shown to have properties similar to HPDC. All other sand cast conditions, including the previously tested Al-9Si-3Cu-(Fe) alloy, have been shown to be reasonable alternatives.

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Llano, Trueba Leticia. "Patterns of corroded rebar surfaces and their impact on tensile mechanical properties." Thesis, University of Surrey, 2015. http://epubs.surrey.ac.uk/808602/.

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Chloride-induced corrosion is regarded as one of the most important sources of deterioration in reinforced concrete (RC) structures, whose maintenance during their service life is of foremost importance in order to avoid unnecessary human risks and economic losses. The availability of effective mechanisms for quantifying the condition and performance of these structures is, therefore, indispensable. The search for improved methods to assess this type of corrosion and its impact on tensile mechanical properties is the main objective of this research. Time variant non-spatial models are currently the methods of choice for the assessment of the effect of corrosion on the mechanical properties of reinforcing bars. Although these models, based on the relationship between mechanical properties and critical points in the geometry, give fairly good predictions, they still leave room for improvement. The consideration of the spatial component of corrosion has barely been addressed in relation to reinforcing bars embedded in concrete. Thus, the present study focuses on the spatial structure of chloride-induced corrosion on steel reinforcing bars and its effects on mechanical properties using a variety of approaches. The use of innovative techniques, originating from different disciplines and applications, has offered new possibilities in tackling this problem. First, based on the application of anodic current to steel reinforcing bars embedded in concrete from an external power source, a set of artificially corroded bars, at different degrees of severity, was produced. The use of a three-dimensional (3D) computerized imaging methodology was utilised to characterise these rebars in terms of a grid of corrosion depth measurements. After the acquisition of these measurements, use was made of a variety of surface metrology and image analysis techniques, through which a number of intensity, texture and shape corrosion quantifiers have been proposed for the spatial characterisation of corrosion patterns. Surface-metrological based parameters and image analysis-based features were found to yield useful metrics to investigate the corrosion structure of corroded rebars. The lack of an objective definition for a pit could be overcome with the characterisation of corrosion defects in terms of their depth and size using image segmentation. All the corroded bars were subjected to a uniaxial tension test and the relevant tensile mechanical properties throughout the strain-stress response were recorded. It was confirmed that traditional non-spatial corrosion models had limitations in terms of identifying and utilising a single corrosion quantifier, and, as a result, the introduction of different possible spatial corrosion quantifiers was investigated, in order to improve the model performance. It was concluded that the addition of spatial quantifiers as predictors, resulted in improved predictions of mechanical properties, compared to the currently used non-spatial models. However, for the range of corrosion levels examined in this study, the improvement in the prediction was relatively modest (circa 10% on the coefficient of determination), confirming the maximum corrosion depth or the minimum cross-sectional area as the pre-eminent quantifiers. The range of techniques developed in this thesis can be implemented in other applications where spatial corrosion characteristics need to be explored.

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Shen, Zhilei Liu. "Tensile Mechanical Properties of Isolated Collagen Fibrils Obtained by Microelectromechanical Systems Technology." Case Western Reserve University School of Graduate Studies / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1278977802.

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Li, Guang. "The effect of moisture content on the tensile strength properties of concrete." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0004782.

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Krus, David Jr. "Finite element analysis of thin film mechanical properties." Case Western Reserve University School of Graduate Studies / OhioLINK, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=case1059745475.

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34

Rudov-Clark, Shoshanna Danielle, and srudov-clark@phmtechnology com. "Experimental Investigation of the Tensile Properties and Failure Mechanisms of Three-Dimensional Woven Composites." RMIT University. AEROSPACE, MECHANICAL AND MANUFACTURING ENGINEERING, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080808.115853.

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This PhD thesis presents an experimental investigation into the tensile properties, strengthening mechanics and failure mechanisms of three-dimensional (3D) woven composites with through-the-thickness (z-binder) reinforcement. 3D composites are being developed for the aerospace industry for structural applications in next-generation aircraft, such as wing panels, joints and stiffened components. The use of 3D woven composites in primary aircraft structures cannot occur until there has been a detailed assessment of their mechanical performance, including under tensile loading conditions. The aim of this PhD project is to provide new insights into the in-plane tensile properties, fatigue life, tensile delamination resistance and failure mechanisms of 3D woven composites with different amounts of z-binder reinforcement. Previous research has revealed that excessive amounts of z-binder reinforcement dramatically improves the tensile delamination toughness, but at the expense of the in-plane structural properties. For this reason, this PhD project aims to evaluate the tensile performance of 3D woven composites with relatively small z-binder contents (less than ~1%). The research aims to provide a better understanding of the manufacture, microstructure and tensile properties of 3D woven composites to assist the process of certification and application of these materials to aircraft structures as well as high performance marine and civil structures.

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Pham, Khang Duy. "Quasi-Static Tensile and Fatigue Behavior of Extrusion Additive Manufactured ULTEM 9085." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/82047.

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Extrusion additive manufacturing technologies may be utilized to fabricate complex geometry devices. However, the success of these additive manufactured devices depends upon their ability to withstand the static and dynamic mechanical loads experienced in service. In this study, quasi-static tensile and cyclic fatigue tests were performed on ULTEM 9085 samples fabricated by fused deposition modeling (FDM). First, tensile tests were conducted following ASTM D638 on three different build orientations with default build parameters to determine the mechanical strength of FDM ULTEM 9085 with those supplied by the vendor. Next, different build parameters (e.g. contour thickness, number of contours, contour depth, raster thickness, and raster angle) were varied to study the effects of those parameters on mechanical strength. Fatigue properties were investigated utilizing the procedure outlined in ASTM D7791. S-N curves were generated using data collected at stress levels of 80%, 60%, 30% and 20% of the ultimate tensile stress with an R-ratio of 0.1 for the build orientation XZY. The contour thickness and raster thickness were increased to 0.030 in. to determine the effect of those two build parameters on tension-tension fatigue life. Next, the modified Goodman approach was used to estimate the fully reversed (R=-1) fatigue life. The initial data suggested that the modified Goodman approach was very conservative. Therefore, four different stress levels of 25%, 20%, 15% and 10% of ultimate tensile stress were used to characterize the fully reversed fatigue properties. Because of the extreme conservatism of the modified Goodman model for this material, a simple phenomenological model was developed to estimate the fatigue life of ULTEM 9085 subjected to fatigue at different R-ratios.
Master of Science

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Li, Xuan. "Hydrogen Effects on X80 Steel Mechanical Properties Measured by Tensile and Impact Testing." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6110.

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The effect of hydrogen charging current density and tensile strain rate on the mechanical properties of X80 pipeline steel were investigated by slow strain rate test (SSRT), Charpy impact test, and scanning electron microscopy (SEM) in this thesis. The results show that both the ultimate tensile strength and elongation to failure of X80 steel were deteriorated significantly after charging with hydrogen. With a strain rate of 5 x 10-5 s-1, the relative tensile strength and plasticity loss of X80 steel had no significant change within the range of assumed hydrogen partial pressures at room temperature. At room temperature, X80 steel had no apparent variation in ultimate tensile strength and elongation, except at the strain rate of 10-6 s-1. Specimens obtained the greatest relative tensile strength loss and plasticity loss when strained at 10-6 s-1 with a current density of 4.6 mA/cm2. The fracture morphology of two test groups of X80 steel exhibited significant brittle rupture when tested with dynamic hydrogen charging. The impact energy of X80 was not affected by hydrogen charging. Different current density also had no influence on the results of the impact test.

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Johansson, Frans. "Optimizing Fused Filament Fabrication 3D printing for durability : Tensile properties and layer bonding." Thesis, Blekinge Tekniska Högskola, Institutionen för maskinteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-12355.

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With the rapid increase in utilization of the cheap and user friendly Fused Filament Fabrication, FFF 3D printer, a deeper knowledge about the technique is needful. The frame restricting the 3D printers for prototyping purposes is fading and a new phase of endless application possibilities is emerging. To bridge the gap in possible applications from prototypes to real products it is key to know and improve the factors affecting durability. With over a hundred settings and parameters to tweak the FFF 3D printing process there are a lot of opportunities, opportunities to optimize for durability.The tensile properties of some of the most used FFF 3D printing materials together with a few nylon based materials are examined, which are popular in engineering applications. The materials tested are ranging from rigid to flexible, rubber like materials. The most common failure scenario of a FFF 3D printed product is layer bonding failure. The factors affecting layer bonding performance are studied.The measurements are carried out using tensile testing equipment at Blekinge Institute of Technology. All tested specimens are manufactured at Creative Tools AB Halmstad with the FFF 3D printers Flashforge Dreamer and Makerbot Replicator 2X.The tensile strength of 3D printed PLA is found to be 51 MPa. PET has a tensile strength of 40 MPa and ABS 34 MPa. Stress-strain behavior of the materials shows that ABS is slightly softer than PLA and PET are slightly softer than ABS. PLA being the hardest material in the test. ISO 527-2 tensile testing standard is used but the tests diverge from the standard in several ways. The measurement data presented in this study can be very useful to guide the design engineer to choose the most durable plastic for the unique application.Five basic 3D printing settings are evaluated for layer bonding performance, by measuring the load capacity of a PLA specimen loaded transversally relative to the layers. Four of the settings show to possibly affect the layer bond’s load capacity by 50 % or more individually.The results of this study are presented in graphs, diagrams and pictures. These may help the 3D printer user to tweak basic settings to increase layer bonding performance and ultimately the durability of the product significantly.

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Algar, Natalie. "Stretched to the limit : leaf tensile properties and lignin content of resurrection plants." Bachelor's thesis, University of Cape Town, 2004. http://hdl.handle.net/11427/24939.

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Leaf tensile strength was measured for four resurrection plants, Craterostigma wilmsii Engl, Xerophyta schlecteri (Baker) N.L. Menezes, Xerophyta humilis (Baker) T. Durand & Schinz and Sporobolus stapfianus Gandoger, as well as two desiccation-sensitive controls, Zea mays L. and Arabidopsis thaliana (L.) Heynh. (ecotype Columbia) at full hydration and after dehydration, both on the plant (naturally-dried) and rapidly off the plant causing death (flash-dried). In the desiccation-tolerant plants, leaf tensile strength was higher in the monocots than the dicots at full hydration. Three different mechanisms of cell protection occur in resurrection plants on drying: cell-wall folding, packing vacuoles with non-aqueous solute or a combination of the two. Tensile strength in C. wilmsii ( dicot) increased when naturally-dried but decreased when flash-dried, possibly due to the nature of the drying mechanisms (wall folding). The, leaf tensile strength of the Xerophyte species, both monocots, increased when naturally dried and when flashdried. Xerophyte species pack their vacuoles during desiccation. S. stapfianus, a grass which uses a combination of wall folding and vacuole packing, had the highest tensile strength possibly due to its unique architectural structure. Differences in leaf architecture, in terms of lignin content, were examined using light microscopy after histo-chemical staining for lignin, which showed that monocotyledons had a higher percentage of lignin per unit leaf cross-sectional area than dicotyledons. A regression analysis revealed that leaf tensile strength and lignin content were positively correlated in fully hydrated leaves I but no relationship existed between lignin content and naturally dried leaves. This may be due to variations of protective mechanisms induced during desiccation by the four resurrection plants. Notching was observed in X schlechteri, behaving differently to grasses which are notch-insensitive, possibly due to large lignin contents on the outer edges of the leaves.

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Ozdes, Huseyin. "The Relationship Between High-Cycle Fatigue and Tensile Properties in Cast Aluminum Alloys." UNF Digital Commons, 2016. http://digitalcommons.unf.edu/etd/716.

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Cast aluminum alloys are common in automotive and aerospace applications due to their high strength-to-density ratio. Fracture data for cast aluminum alloys, such as fatigue life, tensile strength and elongation, are heavily affected by the structural defects, such as pores and bifilms. There have been numerous studies in which either fatigue performance or tensile deformation were characterized and linked to casting defects. However, a comprehensive study that correlates tensile and fatigue properties has not been reported. The present study is motivated to fill this gap. The main objective of the investigation is to analyze the link between tensile and fatigue performance of commonly used cast aluminum alloys, and determine whether fatigue performance of cast aluminum alloys can be predicted. To accomplish this task, four research questions were developed: (i) how well do equations developed to account for mean stress effects perform in cast aluminum alloys, especially in datasets with various levels of structural quality, (ii) is the strong correlation between fatigue life and structural quality index obtained from tensile data reported for A206 alloy castings applicable to other aerospace and automotive casting alloys, (iii) how do methods to estimate high cycle fatigue from tensile data perform with aluminum castings, and (iv) can the axial fatigue performance of an A356-T6 casting be predicted from rotating beam fatigue data. Among the three mean stress correction models analyzed by using seven datasets from the literature, the one developed by Walker with an adjustable exponent has provided the best fit. It has been hypothesized that the adjustable Walker parameter is related to the structural quality index, QT, estimated from tensile data. Results have shown that there is indeed a strong correlation between QT and the Walker parameter. Moreover the parameters of the xvi Weibull distribution estimated from corrected data have been found to be strongly influenced by the mean stress correction method used. Tensile and fatigue life data for 319, D357 and B201 aluminum alloy castings reported in the literature have been reanalyzed by using a maximum likelihood method to estimate Basquin parameters in datasets with run-outs, Weibull statistics for censored data and mean stress correction. After converting tensile data to QT, a distinct relationship has been observed between the expected fatigue life and mean quality index for all alloys. Moreover, probability of survival in fatigue life has been found to be directly linked to the proportions of the quality index distributions in two different regions, providing further evidence about the strong relationship between elongation, i.e., structural quality, and fatigue performance [1]. Specimen geometry has been found to make the largest difference whereas the two aerospace alloys, B201 and D357, with distinctly different microstructures, have followed the same relationship, reinforcing the findings in the literature that fatigue life in aluminum castings is mainly determined by the size distribution and number density of structural defects. Six methods to predict fatigue life from tensile data have been compared by using data from the literature as well as the experimental A356 data developed in this study. Results have shown that none of the six methods provide reliable results. The consistently poor performance of the methods developed for steels and wrought alloys can be attributed to the major structural defects, namely bifilms, in aluminum castings. A new method to estimate the S-N curve from tensile data have been developed by using data for seventy-one S-N curves have been collected and Basquin parameters have been determined. Analysis showed that there is a strong relationship between QT and the Basquin exponent. xvii The Basquin parameters estimated by using the empirical relationships developed in the present study have provided better fits to the same datasets tested for the six methods. Hence the model developed in this study is proposed as the most reliable method to estimate high cycle fatigue properties. Finally, three methods to convert rotating bending fatigue test results to uniaxial fatigue data have been investigated by using the data developed in this study. Results have indicated that the method developed by Esin, in which both the fatigue life and alternating stress are corrected, provide the best estimate. Analyses of fracture surfaces of broken specimens via scanning electron microscopy have shown that tensile, axial fatigue and rotating beam fatigue properties are all strongly influenced by the same structural defects, confirming the validity of the approach taken in this study.

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Cyril, Nisha S. "Anisotropy and Sulfide Inclusion Effects on Tensile Properties and Fatigue Behavior of Steels." Connect to full text in OhioLINK ETD Center, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=toledo1198808409.

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Thesis (M.S.)--University of Toledo, 2007.
Typescript. "Submitted as partial fulfillment of the requirements for the Master of Science Degree in Mechanical Engineering." "A thesis entitled"--at head of title. Bibliography: leaves 204-209.

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Roth, Michael Jason 1975. "Flexural and tensile properties of thin, very high-strength, fiber-reinforced concrete panels." Master's thesis, Mississippi State : Mississippi State University, 2007. http://library.msstate.edu/etd/show.asp?etd=etd-11062007-215816.

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Malpally, Deepthi Rao. "Uncertainty Analysis of Mechanical Properties from Miniature Tensile Testing of High Strength Steels." DigitalCommons@USU, 2014. https://digitalcommons.usu.edu/etd/4029.

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This Miniature mechanical testing study is concerned with the use of miniature specimens to identify the mechanical properties of stainless steel Type 304, sensitized Type 304 and SA516 Grade 70 carbon steel as a viable replacement for the standard sized mechanical testing. The study aims at obtaining suitable specimen geometry and tensile testing proce- dure for miniature mechanical testing whose mechanical properties are comparable to that of conventional specimens of ASTM A370-10 of the same steel. All specimens are at and the gauge length cross section will be varied to obtain suitable geometry. The miniature tensile testing results are further validated by using Monte Carlo Method (MCM) for uncertainty estimation in order to know the probability distribution of mechanical properties. Miniature specimens with a cross section of 3 mm2 and 12 mm gauge length are found to produce equiva- lent mechanical properties as tested from standard-sized specimens. If a reasonable agreement is received, it will provide us with a very useful tool to evaluate mechanical properties of de- graded materials, which cannot be removed from service for standard testing, for repair and service life evaluation.

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Toole, Geraldine. "Mechanical properties of the Chara corallina cell wall and lettuce cultivar tissues." Thesis, University of East Anglia, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365029.

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Bhatia, Krishan. "USE OF NEAR INFRARED SPECTROSCOPY AND MULTIVARIATE CALIBRATION IN PREDICTING THE PROPERTIES OF TISSUE PAPER MADE OF RECYCLED FIBERS AND VIRGIN PULP." Miami University / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=miami1077768497.

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Clarke, Andrew Bryson. "Mechanical properties and process conversion of a novel form of unidirectional carbon fibre/epoxy rod." Thesis, University of Bristol, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267007.

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Mulligan, D. R. "The effect of fibre-bundling on the mechanical properties of a short-fibre composite." Thesis, University of Surrey, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313260.

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It has been suggested that the use of fibre bundles rather than individual fibres can improve the toughness properties of a short-fibre composite. Previous experimental work on this topic employed materials in which bundles were impregnated prior to manufacture or materials with poorly defined fibre-bundling. This study is the first to consider the mechanical properties of a series of materials where the bundles have been impregnated during manufacture of the material, and the materials tested contained a well-defined proportion of fibres within bundles of a known size. A novel manufacturing technique has been developed that can be used to produce short carbon fibre reinforced polypropylene materials with a controlled proportion of fibres in bundles. Materials manufactured in this work contained 0 %, 25 %, 50 %, 75 % and 100 % of the fibres in bundles. The fibres had a length of 5 mm or 10 mm and the bundles contained either 1000 or 6000 fibres. An increase in the proportion of fibres within bundles results in a decrease in the tensile modulus of the short-fibre composites. This decrease was less severe for materials containing bundles with a greater aspect ratio or laminates with a greater thickness. A model for the modulus of the materials has been developed which illustrates some of the effects of fibre-bundling on the structure of a short-fibre composite. For the materials studied, tensile strength of materials containing bundles was one quarter of the tensile strength of the filamentised material. Only one combination of fibre length and bundle size resulted in a clear increase in toughness, as measured by JJ, compared to the filamentised material and this increase appears to be due to areas of unreinforced matrix in the material. Materials containing both filamentised fibres and fibre bundles had relatively low values of J, The fracture surfaces were imaged and three distinct ways in which a bundle may fail have been identified. Discussion of the fracture mechanisms active in these materials concludes that the use of fibre-bundling to improve toughness is unlikely to be effective due to the mechanism that has been proposed

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Reichard, Brett David. "Uniaxial tensile testing technique to obtain softening response of ultra-high performance concrete under confining pressures." Thesis, Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53866.

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The focus of this thesis is to research and develop a uniaxial tensile testing technique and methodology to attain the post-peak softening response for ultra-high performance concrete under confining pressure. This particular multi-axial behavior is valuable in improving current material models in finite element simulations for US Army applications into hardened target structures.

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Boonkerd, Kanoktip. "EFFECT OF EFFICIENCY OF SULFUR VULCANIZATION ON PROPERTIES OF GUM AND BLACK-FILLED NATURAL RUBBER VULCANIZATES." University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1144259529.

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Caldas, Victor. "Morphology, physical and tensile properties of quench-cooled isotactic polypropylene films and spunbonded fabrics." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40026.

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The room temperature morphology of quench-cooled isotactic polypropylene (iPP) films and its development were investigated by scanning transmittance electron microscopy (STEM) and differential scanning calorimetry (DSC). STEM dark field images revealed that within an amorphous matrix there exist microcrystalline regions, 160 A in size on the average, having the $ alpha$-monoclinic crystal form. Regions of lower crystalline order were also observed which have an $ alpha$-monoclinic crystal form that has a substantially longer b crystallographic axis. DSC studies indicate that during quench-cooling to the glassy state iPP samples attain a low degree of crystalline order to an extent that depends on sample mass. Upon heating from the glassy state, an exothermic transition is observed following the glass transition temperature which corresponds to the formation of the room temperature morphology.
Cross polarization/magic angle spinning (CP/MAS) nuclear magnetic resonance (NMR) spectroscopy was used to monitor morphological changes in the purely crystalline phase of quench-cooled iPP films and spunbonded fabrics during annealing. The spectra were obtained using a pulse sequence that incorporates a delay period with a reduced spin locking field prior to cross polarization. Morphological changes occurring within the purely crystalline phase of iPP were related to observations made by DSC. Upon annealing, the CP/MAS NMR spectrum of the purely crystalline phase of both iPP samples changed by a redistribution in the intensity of the various peaks within a given carbon resonance. This redistribution of intensity was found to reflect the conversion from the $ alpha sb1$ to the $ alpha sb2$ monoclinic crystal forms. It is shown that the double melting endotherm observed by DSC for the spunbonded fabrics is due to the exothermicity which is associated with this conversion. It is concentrated in the temperature region between 156 and 163$ sp circ$C.
The tensile properties of the spunbonded iPP fabrics and fibers were enhanced by the dispersion of a silica/silicone additive and by changing the resin characteristics. This additive acts as a nucleating agent for iPP under isothermal crystallization conditions. This nucleating ability manifests itself in smaller crystal sizes and higher nucleation densities in the iPP fibers and bond points. The improved tensile properties are attributed to the smaller crystal sizes which form a more homogeneously dispersed crystalline phase in the amorphous phase as well as to increase the number of load-bearing tie molecules.

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Twite, M. R. "The tensile properties of aluminium alloys at temperatures both above and below the solidus." Thesis, Swansea University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.639279.

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A programme of mechanical testing has been carried out to measure the tensile properties of one AA5083 and three AA6061 alloys, all of near as-cast microstructure, at temperatures primarily around and above the respective solidus temperatures, and over a range of strain rates. The testing method used in this work (the Advanced Semi Solid Elongation Test, or 'ASSET') allowed the rapid re-heating of specimens to the test temperature in order to attempt to preserve the as-cast microstructure. Accurate tensile properties data were gained for the four alloys tested. Such data may be useful in the computer modelling of industrial solidification processes, for example the Direct Chill casting of aluminium alloy ingots. The tensile strength and ductility of the alloys tested, and the ways in which these properties were found to vary with temperature and strain rate, were found to be dependent on the alloy. Several theories are suggested for the differences in tensile properties found between the four alloys tested. Considerations include the solid grain morphology, the form and distribution of solute elements in the alloys, the nature of change in fraction liquid with temperature variation, the balance of interfacial energies in the semi solid alloy, the effects of deformation rate and the grain size. Two apparent regimes of hot tearing behaviour were identified in one of the alloys tested. Two such regimes may also exist in the other alloys used in this work. A constitutive equation, based on an exponential relationship between maximum tensile stress and temperature, was developed for each of the four alloys tested in this work.

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Dissertations / Theses on the topic 'TENSILE PROPERTIES'

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