Dissertations / Theses on the topic 'Steel, High strength Testing'
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Yosefani, Anas. "Flexural Strength, Ductility, and Serviceability of Beams that Contain High-Strength Steel Reinforcement and High-Grade Concrete." PDXScholar, 2018. https://pdxscholar.library.pdx.edu/open_access_etds/4402.
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Utilizing the higher capacity steel in design can provide additional advantages to the concrete construction industry including a reduction of congestion, improved concrete placement, reduction in the required reinforcement and cross sections which would lead to savings in materials, shipping, and placement costs. Using high-strength reinforcement is expected to impact the design provisions of ACI 318 code and other related codes.
The Applied Technology Council (ATC-115) report "Roadmap for the Use of High-Strength Reinforcement in Reinforced Concrete Design" has identified key design issues that are affected by the use of high-strength reinforcement. Also, ACI ITG-6, "Design Guide for the Use of ASTM A1035 Grade 100 Steel Bars for Structural Concrete" and NCHRP Report 679, "Design of Concrete Structures Using High-Strength Steel Reinforcement" have made progress towards identifying how code provisions in ACI 318 and AASHTO could be changed to incorporate high-strength reinforcement.
The current research aims to provide a closer investigation of the behavior of beams reinforced with high-strength steel bars (including ASTM A615 Grade 100 and ASTM A1035 Grades 100 and 120) and high-strength concrete up to 12000 psi. Focus of the research is on key design issues including: ductility, stiffness, deflection, and cracking.
The research includes an extensive review of current literature, an analytical study and conforming experimental tests, and is directed to provide a number of recommendations and design guidelines for design of beams reinforced with high-strength concrete and high-strength steel. Topics investigated include: strain limits (tension-controlled and compression-controlled, and minimum strain in steel); possible change for strength reduction factor equation for transition zone (Φ); evaluation of the minimum reinforcement ratio (þmin); recommendations regarding limiting the maximum stress for the high-strength reinforcement; and prediction of deflection and crack width at service load levels. Moreover, this research includes long-term deflection test of a beam made with high grade concrete and high-strength steel under sustained load for twelve months to evaluate the creep deflection and to insure the appropriateness of the current ACI 318 time-dependent factor, λ, which does not consider the yield strength of reinforcement and the concrete grade.
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Chen, Ju, and 陳駒. "Behaviour of high strength steel columns at elevated temperatures." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B37936554.
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Jiao, Hui 1963. "The behaviour of very high strength (VHS) members and welded connections." Monash University, Dept. of Civil Engineering, 2003. http://arrow.monash.edu.au/hdl/1959.1/9417.
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Karlsson, Daniel. "Life and fracture in very high cycle fatigue of a high strength steel." Thesis, Karlstads universitet, Institutionen för ingenjörsvetenskap och fysik (from 2013), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-86135.
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Classical fatigue models teach that there is an intrinsic fatigue limit for steels, representing a level of stress that is too low for regular crack growth where every cyclic load propagates a fatigue crack through the material. Modern application with extreme lifetimes has shown that fatigue will still take place in steels with stress levels well below the expected fatigue limit. This relatively new area of study has been named Very High Cycle Fatigue, or VHCF, and describes fatigue failures with a number of load cycles exceeding 107. Fractography of steels that has suffered VHCF tends to reveal an especially rough crack surface adjacent to where the fatigue crack originates, which is typically some form of defect in the bulk of the steel. This area is believed to be critical for VHCF and has been referred to in a number of ways by different studies, but will herein be called Fine Granular Area, or FGA. The aim of this study is to try and get a better understanding of VHCF. This was done by fractography analysis of test specimens of high strength tool steel that suffered fatigue failure at lifetimes ranging from about 106 cycles to 1,9x109 cycles. The lower lifetimes were achieved using hydraulic testing equipment, while the specimens in the VHCF range suffered fatigue failure in ultrasonic testing equipment allowing the application of a cyclic stress at a rate of 20 000 Hz. The resulting fracture surfaces were then investigated using a scanning electron microscope, or SEM, taking special note of the fatigue initiating defects and, in the case of VHCF, the rough area found adjacent to it. In combination with the SEM an elemental analysis of the fatigue initiating defects as well as the bulk of the material was done using energy-dispersive X-ray spectroscopy, or EDS. This was done to find out what the defects consisted of; confirming that they were slags and checking that the composition of the material of the bulk of the specimen matches what was expected. Using light optical microscopy in combination with acid etching of the surface of samples cut out of the test specimens the structure of the steel was investigated. Calculating the local stresses at the location of the fatigue initiating defect was done using FEM in combination with displacement amplitude gathered from the ultrasonic testing equipment. The data gathered was then measured and compared to that of previous studies, using models of prediction and seeing how they match the experimental results. The results suggest that the stress intensity factor at the internal slags is critical for VHCF and that with lower stress intensity factors one can expect longer lifetimes. Another observation is a relatively consistent stress intensity factor at the edge of the FGA combined with the original defect, likely signifying the transition from the creation of FGA to traditional crack propagation. There also seems to be a connection between the size of the FGA and the number of cycles to failure, with larger FGA with increasing lifetimes. The most glaring shortcoming of this study is the amount satisfactory tests conducted, and thus amount of data points, is very low due to the majority of specimens suffered failure at the threading used to connect them to the ultrasonic testing equipment at lifetimes far too low to be relevant.Klassiska utmattningsmodeller lär ut att det finns en utmattningsgräns för stål, vilket representerar en spänningsnivå som är för låg för regelbunden sprickväxt där varje cyklisk belastning sprider en utmattningsspricka genom materialet. Moderna applikation med extrema livstider har visat att utmattning fortfarande äger rum i stål med spänningsnivåer långt under den förväntade utmattningsgränsen. Detta relativt nya studieområde har fått namnet Very High Cycle Fatigue, eller VHCF, och beskriver utmattningsfall med ett antal belastningscykler som överstiger 107. Fraktografi av stål som har drabbats av VHCF tenderar att ha en särskilt gropig sprickyta som ligger intill där utmattningssprickan har sitt ursprung, vilket typiskt är någon form av defekt i stålets bulk. Detta område tros vara kritiskt för VHCF och har hänvisats till på ett antal sätt av olika studier, men kommer här att kallas Fine Granular Area eller FGA. Syftet med denna studie är att försöka få en bättre förståelse för VHCF. Detta gjordes genom fraktografianalys av testprover av verktygsstål med hög hållfasthet som drabbades av utmattningsbrott vid livstider från cirka 106 cykler till 1,9x109 cykler. De lägre livslängderna uppnåddes med hjälp av hydraulisk testutrustning, medan proverna i VHCF-området drabbades av utmattningsbrott i ultraljudstestutrustning som klarar att applicera en cyklisk stress med en frekvens på 20 kHz. De resulterande sprickytorna undersöktes sedan med hjälp av ett svepelektronmikroskop, eller SEM, med särskild fokus på utmattningsinitierande defekter och, i fallet med VHCF, det grova området som hittades intill det, FGA. I kombination med SEM utfördes en elementanalys av utmattningsinitierande defekter liksom huvuddelen av materialet med energidispersiv röntgenspektroskopi, eller EDS. Detta gjordes för att ta reda på vad inneslutningarna bestod av för att bekräfta att de var slagg samt kontrollera att sammansättningen av materialet i huvuddelen av provet matchar det som förväntades. Med användning av optisk ljusmikroskopi i kombination med syraetsning av ytan på prover som skars ut ur testproverna undersöktes stålets struktur. Beräkning av de lokala spänningarna på platsen för den utmattningsinitierande defekten gjordes med hjälp av FEM i kombination med förskjutningsamplituden som samlats från ultraljudsutrustningen. De insamlade uppgifterna mättes sedan och jämfördes med tidigare studier genom att använda diverse modeller och se hur de matchar de experimentella resultaten. Resultaten antyder att stressintensitetsfaktorn vid inneslutningarna är kritisk för VHCF och att man med lägre stressintensitetsfaktorer kan förvänta sig längre livstid. En annan observation är en relativt konsekvent stressintensitetsfaktor vid kanten av FGA, vilket sannolikt markerar övergången från skapandet eller utbredning av FGA till traditionell sprickutbredning. Det verkar också finnas en koppling mellan storleken på FGA och antalet cykler till fel, med större FGA med ökande livslängd. Den mest uppenbara bristen i denna studie är mängden tillfredsställande tester som genomförts. Därmed är mängden datapunkter mycket låg, detta på grund av att majoriteten av proverna misslyckades vid gängningen som användes för att ansluta dem till ultraljudstestutrustningen vid livstider alltför låga för att vara relevanta.
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Peer, Andrea J. "Performance Testing and Modeling of Ultra-High Strength Steel and Complex Stack-Up Resistance Spot Welds." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1493403670252986.
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Tantbirojn, Natee. "Fatigue testing of weldable high strength steels under simulated service conditions." Thesis, University College London (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399077.
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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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Arakelian, Andrea Katherine. "Strength analysis of bolted shear connections under fire conditions using the finite element approach." Worcester, Mass. : Worcester Polytechnic Institute, 2008. http://www.wpi.edu/Pubs/ETD/Available/etd-122208-145717/.
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Ghasemi, Sahar. "Innovative Modular High Performance Lightweight Decks for Accelerated Bridge Construction." FIU Digital Commons, 2015. http://digitalcommons.fiu.edu/etd/2248.
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At an average age of 42 years, 10% of the nation’s over 607,000 bridges are posted for load restrictions, with an additional 15% considered structurally deficient or functionally obsolete. While there are major concerns with decks in 75% of structurally deficient bridges, often weight and geometry of the deck further limit the load rating and functionality of the bridge. Traditional deck systems and construction methods usually lead to prolonged periods of traffic delays, limiting options for transportation agencies to replace or widen a bridge, especially in urban areas.
The purpose of this study was to develop a new generation of ultra-lightweight super shallow solid deck systems to replace open grid steel decks on movable bridges and as well serve as a viable alternative in bridge deck replacements across the country. The study has led to a lightweight low-profile asymmetric waffle deck made with advanced materials. The asymmetry comes from the arrangement of primary and secondary ribs, respectively perpendicular and parallel to the direction of traffic. The waffle deck is made with ultrahigh performance concrete (UHPC) reinforced with either high-strength steel (HSS) or carbon fiber reinforced polymer (CFRP) reinforcement. With this combination, the deck weight was limited to below 21 psf and its overall depth to only 4 inch, while still meeting the strength and ductility demands for 4 ft. typical stringer spacing. It was further envisioned that the ultra-high strength of UHPC is best matched with the high strength of HSS or CFRP reinforcement for an efficient system and the ductile behavior of UHPC can help mask the linear elastic response of CFRP reinforcement and result in an overall ductile system. The issues of consideration from the design and constructability perspectives have included strength and stiffness, bond and development length for the reinforcement, punching shear and panel action. A series of experiments were conducted to help address these issues. Additionally full-size panels were made for testing under heavy vehicle simulator (HVS) at the accelerated pavement testing (APT) facility in Gainesville. Detailed finite element analyses were also carried out to help guide the design of this new generation of bridge decks. The research has confirmed the superior performance of the new deck system and its feasibility.
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Larsson, Rikard. "Constitutive Modelling of High Strength Steel." Thesis, Linköping University, Department of Management and Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-8157.
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This report is a review on aspects of constitutive modelling of high strength steels. Aspects that have been presented are basic crystallography of steel, martensite transformation, thermodynamics and plasticity from a phenomenological point of view. The phenomenon called mechanical twinning is reviewed and the properties of a new material type called TWIP-steel have been briefly presented. Focus has been given on phenomenological models and methods, but an overview over multiscale methods has also been given.
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Taylor, H. "Fatigue behaviour in high strength steel." Thesis, University of Salford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372146.
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Skoglund, Oskar. "Innovative structural details using high strength steel for steel bridges." Licentiate thesis, KTH, Bro- och stålbyggnad, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-259949.
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The use of high strength steel has the potential to reduce the amount of steel used in bridge structures and thereby facilitate a more sustainable construction. The amount of steel and what steel grade that can be used in bridge structures and other cyclic loaded structures are often limited by a material degradation process called fatigue. The fatigue resistance of steel bridges are to a large extent depending on the design of structural details and connections. The design engineer is limited by a few pre-existing structural details and connections – with rather poor fatigue resistance – to choose from when designing steel bridges, and is therefore often forced to increase the overall dimensions of the structure in order to cope with the design requirements of fatigue. This licentiate thesis aims at increasing the fatigue resistance of fatigue prone structural details and connections by implementing new and innovative structural solutions to the already pre-existing details given in the design standards. A typical fatigue prone detail is the vertical stiffener at an intermediate cross-beam, which will be in focus. By improving the fatigue resistance, less steel material will be required for the construction of new steel bridges and composite bridges of steel and concrete. It is shown in this thesis and the appended papers that the use of high strength steel for bridge structures can considerably reduce the amount of steel used, the steel cost and the harmful emissions. However, this is only true if the fatigue strength of critical details can be substantially improved. Furthermore, a few new and innovative structural details and modifications to already existing details are proposed in this thesis and in the appended papers, that have the potential to increase the fatigue resistance of steel bridges and composite bridges of steel and concrete. However, further analyses are required in order to make these structural details viable for construction.Genom användandet av höghållfast stål så kan en mindre mängd material användas som i sin tur leder till ett mer hållbart byggande. Mängden stål och vilken stålkvalité som kan användas vid byggandet av stålbroar och andra cykliskt belastade konstruktioner avgörs ofta av nedbrytningsprocessen utmattning. Utmatningskapaciteten hos stålbroar är till stor del beroende av brons anslutningsdetaljer. Brokonstruktören har vid designstadiet ett begränsat antal beprövade anslutningsdetaljer att välja bland – vilka ofta har relativt låg utmattningskapacitet – och konstruktören är därmed ofta tvungen att öka konstruktionens dimensioner för att klara av kraven gällande utmattning. Den har licentiatuppsatsen har till syfte att förbättra utmattningskapaciteten för utmattningsbenägna anslutningsdetaljer i stål genom att införa nya och innovativa anslutningsdetaljer, bland de redan existerande detaljerna som finns i de olika standarderna. En utmattningskritisk detalj som kommer att ligga i fokus är anslutningen mellan livavstyvningen och tvärförbanden hos en I-balk. Genom att förbättra utmattningskapaciteten så kan en mindre mängd stålmaterial användas vid byggandet av stålbroar och samverkansbroar i betong och stål. I denna uppsatsen kunde det påvisas att höghallfast stål for broar kan betydligt sänka mängden stålmaterial, stålkostnaden och koldioxidutsläppen. Dock så gäller detta enbart om utmattningskapaciteten for kritiska anslutningsdetaljer kan ökas avsevärt. Dessutom, som en del av den har uppsatsen så har ett par nya och innovativa anslutningsdetaljer föreslagits som har potential att forbättra utmattningskapaciteten. Dock, så krävs ytterligare studier for att dessa förslag skall kunna användas i byggnation av nya stålbroar.
QC 20190925
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Goodall, Graeme. "Welding High Strength Modern Line Pipe Steel." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=96662.
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The effect of modern mechanized girth welding on high strength line pipe has been investigated. The single cycle grain coarsened heat affected zone in three grade 690 line pipe steels and a grade 550 steel has been simulated using a Gleeble thermo-mechanical simulator. The continuous cooling transformation diagrams applicable to the grain coarsened heat affected zone resulting from a range of heat inputs applicable to modern mechanized welding have been established by dilatometry and metallography. The coarse grained heat affected zone was found to transform to lath martensite, bainite, and granular bainite depending on the cooling rate. The impact toughness of the steels was measured using Charpy impact toughness and compared to the toughness of the grain coarsened heat affected zone corresponding to a welding thermal cycle. The ductile to brittle transition temperature was found to be lowest for the steel with the highest hardenability. The toughness resulting from three different thermal cycles including a novel interrupted intercritically reheated grain coarsened (NTR ICR GC HAZ) that can result from dual torch welding at fast travel speed and close torch spacing have been investigated. All of the thermally HAZ regions showed reduced toughness that was attributed to bainitic microstructure and large effective grain sizes. Continuous cooling transformation diagrams for five weld metal chemistries applicable to mechanized pulsed gas metal arc welding of modern high strength pipe steel (SMYS>550 MPa) have been constructed. Welds at heat inputs of 1.5 kJmm-1 and 0.5 kJmm-1 have been created for simulation and analysis. Dilatometric analysis was performed on weld metal specimens cut from single pass 1.5 kJmm-1 as deposited beads. The resulting microstructures were found to range from martensite to polygonal ferrite. There is excellent agreement between the simulated and as deposited weld metal regions. Toughness testing indicates improved energy absorption at -20 °C with increased cooling time.L'effet des méthodes modernes de soudage circonférentiel mécanisé sur des aciers à forte résistance utilisés pour les tubes de canalisation a été investigué. La zone affectée thermiquement ayant subi une croissance de grain lors d'un cycle thermique simple de soudage a été simulée pour trois grades d'acier à tubes de canalisation 690 et un grade d'acier 550 à l'aide d'un appareil de simulation thermomécanique Gleeble. Les diagrammes de transformation en refroidissement continu pour la zone affectée thermiquement ayant subi une croissance de grains ont été établis pour un spectre de chaleur induite représentatif du procédé de soudage mécanisé en utilisant la dilatométrie ainsi que des analyses métallographiques. Il résulte que la zone affectée thermiquement ayant subi une croissance de grain connaît un changement de phase vers une martensite massive, une bainite ou une bainite granulaire selon le taux de refroidissement rencontré. La résistance des aciers étudiés a été mesurée par essais Charpy et comparée à la résistance obtenue pour la zone affectée thermiquement ayant subi une croissance de grains correspondant à un cycle thermique de soudage. Le plus bas température de transition ductile-fragile a été obtenue pour les grades d'acier ayant la plus grande aptitude à la trempe. La résistance résultante des structures obtenues pour trois différents cycles thermique, notamment un nouveau cycle thermique interrompu par recuit intercritique similaire à l'effet que peut avoir un soudage à double torche à déplacement rapide et espacement réduit, a été étudié. Toutes les zones affectée thermiquement montrent une baisse de résistance causée par l'apparition d'une structure bainitique et la croissance des grains.Les diagrammes de transformations en refroidissement continu ont été établis pour 5 alliages de soudage applicable pour le soudage pulsé à l'arc sous gas des aciers à tube modernes à haute résistance. Des soudures avec un apport de chaleur de 1,5 kJmm-1 et 0,5 kJmm-1 ont été utilisées pour les simulations et les analyses. Des essais de dilatométrie ont été faits sur des échantillons prélevés des cordons de soudure déposés en une passe à 1,5 kJmm-1. L'observation métallographique des échantillons présente une structure allant de la martensite à la ferrite polygonale. Une excellente concordance a été établie entre la structure du métal obtenu par simulation et telle que déposé. Les tests de résistance indiquent une amélioration de l'énergie absorbée à -20°C lorsque le temps de refroidissement est plus long.
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Björklund, Oscar. "Ductile Failure in High Strength Steel Sheets." Doctoral thesis, Linköpings universitet, Hållfasthetslära, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-105213.
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Developments in computer-aided engineering and the rapid growth of computational power have made simulation-driven process and product development efficient and useful since it enables detailed evaluation of product designs and their manufacturing processes. In the context of a sheet metal component, it is vital to predict possible failure both during its forming process and its subsequent usage. Accurate numerical models are needed in order to obtain trustworthy simulation results. Furthermore, the increasing demands imposed on improved weight-to-performance ratio for many products endorse the use of high-strength steels. These steels often show anisotropic behaviour and more complex hardening and fracturing compared to conventional steels. Consequently, demand for research on material and failure models suitable for these steels has increased. In this work, the mechanical and fracture behaviour of two high-strength steels, Docol 600DP and Docol 1200M, have been studied under various deformation processes. Experimental results have been used both for material characterisation and for calibration of fracture criteria. One major requirement as concerns the fracture criteria studied is that they should be simple to apply in industrial applications, i.e. it should be possible to easily calibrate the fracture criteria in simple mechanical experiments and they should be efficient and accurate. Consequently, un-coupled phenomenological damage models have been the main focus throughout this work. Detailed finite element models including accurate constitutive laws have be used to predict and capture material instabilities. Most of the fracture criteria studied are modifications of the plastic work to fracture. Ductile tensile and ductile shear types of fracture are of particular interest in sheet metal applications. For these fractures the modification of the plastic work relates to void coalescence and void collapse, respectively. Anisotropy in fracture behaviour can be captured by the introduction of a material directional function. The dissertation consists of two parts. The first part contains theory and background. The second consists of five papers.
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Konstantarakis, Christos. "Hydrogen degradation of high strength steel weldments." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/47338.
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Thesis (Ocean. E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1993, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science & Engineering, 1993.Includes bibliographical references (leaves 37-43).
by Christos Konstantarakis.
M.S.
Ocean.E.
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Anderson, Cheryl Marie. "The weldability of high and ultra-high strength steel." Thesis, Swansea University, 2003. https://cronfa.swan.ac.uk/Record/cronfa42947.
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Weight reduction in body-in-white structures is necessary to make automobiles more fuel-efficient. A range of high and ultra-high strength strip steels have been developed, that will play a key role in achieving lower weights since the steels have the potential to achieve equivalent strength and crashworthiness at thinner gauges. However, the full potential of these advanced alloys can only be realised if they can be integrated into production facilities that rely on resistance spot welding as the predominant means of component joining. In particular, spot welds manufactured in these modern high strength steels will need to meet the strength and fracture resistance requirements that are based on automotive manufacturers' familiarity with low alloy steels. Dual phase steels are a range of modern alloys causing considerable excitement due to their combination of high strength, high ductility and improved crashworthiness in automotive components, compared to mild steel. Their commercial production routes rely on a metallurgical understanding of how chemical composition and thermomechanical treatments interrelate to produce appropriate microstructures. Their often complex alloy compositions mean that there is potential for significant changes to take place in the microstructure on resistance welding. This research programme has considered the important relationships from which resistance spot-welds, produced in high strength steels, derive their properties. This includes an investigation into the continuous cooling transformation behaviour of four dual phase alloys, in comparison to low alloy grades, and measurement of the mechanical properties associated with their microstructures. The thermal profiles generated within spot welds have been measured using a thermocouple technique. Advanced resistance spot welding processes, that can modify the metallurgical condition of a spot-weld, have been investigated with some success, both in terms of reductions in weld hardness following pulsed welding schedules, and an understanding of the effect of such schedules on the thermal cycle.
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Al-Azzawi, Hosam Abdullah. "Strength Tuned Steel Eccentric Braced Frames." PDXScholar, 2019. https://pdxscholar.library.pdx.edu/open_access_etds/4981.
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The primary component in eccentrically braced frames (EBF) is the link as its plastic strength controls the design of the frame as well as the entire building within which it is installed. EBFs are the first part of building design and every other component is sized based on the forces developed in the link. Oversized link elements lead to the use of unnecessary materials and can increase construction costs. Additionally, the advantages of using a continuous member of the same depth for both the link and the controller beam (in terms of the cost and the time) motivates researchers to find a way to control the link strength in conventional EBFs. Previous studies on the link-to-column connections in EBF have shown that the links are likely to fail before reaching the required rotation due to fractures at low drift level. Moreover, improving the strength of the links in EBF depends primarily on their ability to achieve target inelastic deformation and to provide high ductility during earthquakes. Therefore, in this study, the concept of tuned link strength properties in EBF, T-EBF, is experimentally introduced as a solution to improve the performance of the link in conventional EBF by cutting out an opening in the link web. Furthermore, a new brace-to-link connection is proposed to bolt the brace member with the link in contrast to the conventional method of welding them. This new idea in continuous beam design was investigated to verify the stability of the tuned eccentrically braced frame, either welded or bolted, with a bracing member. A total of four full-scale cyclic tests were conducted to study the ability of T-EBF to achieve inelastic deformation. The specimens have two different cross sections: W18x76 and W16x67, two different sections where the brace was welded to the link, and two other specimens at different sections where the brace was bolted to the link were examined. The experimental results indicate that the link in T-EBF can achieve high rotation, exceeding 0.15 rad, and an overstrength factor equal to 1.5. Failure involved included web buckling at very high rotation. The T-EBF displayed a very good, non-replaceable ductile link. The experiments were followed by an isotropic kinematic-combined hardening model in the finite element analyses (FEA). The FEA analysis is developed to predict the effect of web opening configuration on the local section stresses and strains and global characteristics of the frame. FEA exhibits good agreement with the experimental results and can capture the inelastic buckling behavior of the sections. The link configuration parameters of the T-EBF were studied extensively on a W18x76 shear link subjected to the 2016 AISC seismic design provisions loading protocol (ANSI/AISC 341-16, 2016). The parametric study also included the performance of a range of wide flange sections. The analysis shows that the reduced web section has effect on the plastic strain in which low plastic strain observed near ends and connections and high at the center of the web. Results also demonstrate that if the shear link is appropriately sized with web opening and intermediate web stiffeners provided, an excellent shear link with high ductility under cyclic loads can be obtained. Changing the configuration of the opening cutout also had a significant effect on reducing the transition zone cracks.
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Mitchell, Andrew Douglass. "Shear friction behavior of high-strength concrete." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/19274.
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Larsson, Rikard. "On Material Modelling of High Strength Steel Sheets." Doctoral thesis, Linköpings universitet, Hållfasthetslära, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-80115.
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The work done in this thesis aims at developing and improving material models for use in industrial applications. The mechanical behaviour of three advanced high strength steel grades, Docol 600DP, Docol 1200M and HyTens 1000, has been experimentally investigated under various types of deformation, and material models of their behaviour have been developed. The origins of all these material models are experimental findings from physical tests on the materials. Sheet metal forming is an important industrial process and is used to produce a wide range of products. The continuously increasing demand on the weight to performance ratio of many products promotes the use of advanced high strength steel. In order to take full advantage of such steel, most product development is done by means of computer aided engineering, CAE. In advanced product development, the use of simulation based design, SBD, is continuously increasing. With SBD, the functionality of a product, as well as its manufacturing process, can be analysed and optimised with a minimum of physical prototype testing. Accurate numerical tools are absolutely necessary with this methodology, and the model of the material behaviour is one important aspect of such tools. This thesis consists of an introduction followed by five appended papers. In the first paper, the dual phase Docol 600DP steel and the martensitic Docol 1200M steel were subjected to deformations, both under linear and non-linear strain paths. Plastic anisotropy and hardening were evaluated and modelled using both virgin materials, i.e. as received, and materials which were pre-strained in various material directions. In the second paper, the austenitic stainless steel HyTens 1000 was subjected to deformations under various proportional strain paths and strain rates. It was experimentally shown that this material is sensitive both to dynamic and static strain ageing. A constitutive model accounting for these effects was developed, calibrated, implemented in a Finite Element software and, finally, validated on physical test data. The third paper concerns the material dispersions in batches of Docol 600DP. A material model was calibrated to a number of material batches of the same steel grade. The paper provides a statistical analysis of the resulting material parameters. The fourth paper deals with a simple modelling of distortional hardening. This type of hardening is able to represent the variation of plastic anisotropy during deformation. This is not the case with a regular isotropic hardening, where the anisotropy is fixed during deformation. The strain rate effect is an important phenomenon, which often needs to be considered in a material model. In the fifth paper, the strain rate effects in Docol 600DP are investigated and modelled. Furthermore, the strain rate effect on strain localisation is discussed.SFS ProViking Super Light Steel Structures
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Clarin, Mattias. "High strength steel : local buckling and residual stresses." Licentiate thesis, Luleå, 2004. http://epubl.luth.se/1402-1757/2004/054.
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Schuetz, Daniel Philip. "Investigation of high strength stainless steel prestressing strands." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47744.
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Bridges and other coastal structures in Georgia and throughout the Southeast are deteriorating prematurely due to corrosion. Numerous corrosion
initiated failures have occurred in precast prestressed concrete (PSC) piles and reinforced concrete (RC) pile caps, leading to the costly repair and
replacement of either the entire bridge or the affected members. With the Federal Highway Administration's goal of a 100-year bridge service life
and recent legislative action such as the Bridge Life Extension Act, new emphasis has been placed on the development and implementation of new
corrosion mitigation techniques.
This thesis involves the mechanical testing, and proposed future test program of high-strength stainless steel (HSSS) prestressing strand to be used
in prestressed marine bridge piles. The metallurgy for two types of HSSS strand was selected from a previous study of the corrosion resistance,
mechanical properties, and feasibility of 6 candidate HSSS drawn wire samples. Duplex stainless steel (DSS) grades 2205 and 2304 were selected
for production of 7-wire 1/2" diameter prestressing strand. DSS wire rod was drawn, stranded, and heat-treated using the same production methods
and equipment as used for standard of practice, high carbon prestressing strand. The production process was documented to analyze the problems
facing this production method and suggest improvement and optimization.
After production, the strands were subjected to a series of mechanical tests. Tension testing was performed to provide a stress-strain curve for the
strands and related mechanical properties. Wire samples were also taken at varying points in the drawing process to give more information about
the work hardening of the stainless steels. Stress relaxation testing was performed on both strand and wire samples to assess the overall losses and
to provide comparisons between strand and wire test results as well as drawn wires before and after heat-treatment.
An experimental program for future study was designed to assess the HSSS prestressing strand behavior in precast piles. This testing involves
assessment of pile driving performance, pile flexural and shear behavior, strand transfer and development length, long-term prestressing force
losses, and material durability.
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Wong, T. M. "Stress corrosion cracking in a high strength steel." Thesis, University of Canterbury. Engineering, 1986. http://hdl.handle.net/10092/6429.
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This thesis falls into four fields of study.
The first is a survey of relevant literature concerning the many theories of stress corrosion cracking and hydrogen embritt1ement. This includes descriptions of the mechanisms of stress corrosion cracking (SCC) and outlines electromechanical processes and stress - sorption theory. Four widely accepted mechanisms for environment assisted cracking are also outlined. They are, 1) Embritt1ement resulting from accumulated hydrogen at embritt1ement sites, 2) Lowering of surface energy by adsorption of hydrogen, 3) Hydrogen interaction with dislocations, and 4) Lowering of the binding energy by interaction of hydrogen.
The literature survey is a significant part of this thesis. The overall objective of the survey is to review a series of current SCC tests on high strength steels. The principal findings from these previous studies are summarized, they provide concrete evidence for the conclusion that SCC of high strength steels is due to hydrogen embrittlement.
The second part of the project deals with the development of a stress corrosion loading clevis suitable for testing compact tension specimens. Three existing constant load rigs were developed, and equipment was designed for the successful operation of the rigs.
Corrosive environment was applied to the standard compact tension specimen using a novel circulation system based on a magnetic plate stirrer. Corrosive solution (3.5% NaCl) was stirred by the magnetic plate, and the vortex created by the magnetic stirrer was used to create a pumping head.
The third area of work dealt with the testing of compact tension specimens of ULTIMO 200 steel using the developed apparatus. The experimental procedures used are based on the application of linear elastic fracture mechanics to stress corrosion cracking.
The fourth area of work carried out was to perform slot length calibration experiments on CT specimens by using strain gauges.
The results indicated that the specimens pre-cracked in air with a higher dynamic load gave higher threshold stress intensities (KIscc ) than those pre-cracked in air with a lower dynamic load. An electron microscope study indicated evidence of a largely inter granular fatigue crack having occurred in the specimens pre-cracked with a high dynamic load.
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Gedeon, Steven Anthony. "Hydrogen assisted cracking of high strength steel welds." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14842.
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Wang, Jie. "Behaviour and design of high strength steel structures." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/43758.
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High strength steels (HSS), which are generally considered to be those with yield strengths over 460 MPa, are being increasingly utilised in construction, particularly in high rise structural applications and where long and column-free spans are an important design requirement. In place of ordinary carbon steels, the use of HSS can enable structural elements with smaller cross-sections, resulting in significant material savings. However, compared to normal strength steels, the structural use of HSS is still quite rare. The European design code EN 1993-1-12 provides design rules for HSS up to S700, but was conceived as a simple extension of the rules in EN 1993-1-1 for normal strength steels. In order to contribute to the existing limited HSS data pool and to verify and develop the current Eurocode 3 design rules, a comprehensive experimental programme on hot-finished S460 and S690 square and rectangular hollow sections has been carried out. The testing programme covered different structural aspects at the material, cross-section and member levels and consisted of 40 tensile coupon tests, 11 compressive coupon tests, 11 stub column tests, 11 full section tensile tests, 22 in-plane bending tests, 12 eccentrically loaded stub column tests, 30 long column tests, as well as measurements of geometrical imperfections and residual stresses. Numerical models, validated against the test results, were also developed to examine the cross-section and member behaviour, and subsequently employed in a comprehensive parametric study in order to generate further data. Based on the combined test and numerical data set, as well as experimental results reported in the literature, the current HSS design rules in Eurocode 3, including the slenderness limits for cross-section classification, effective width equation, N-M interaction curves and column buckling curves, were assessed by means of reliability analyses in accordance with Annex D of EN 1990. To realise the potential of HSS in long span structures, a novel structural form was also examined, namely an HSS truss with prestressing cables housed within the tubular bottom chord. A total of 4 prestressed trusses, made of S460 square hollow sections with different prestress levels, were tested under static downward loading. The truss test results showed the enhanced structural efficiency brought about by the addition of prestressing cables and by the application of prestress. Additionally, 12 tensile and 10 compressive member tests with cables, representing the bottom chord of the truss under gravity and uplift loading, respectively, were carried out to investigate the behaviour of individual prestressed cable-in-tube members. Analytical models and numerical models were also established to compare with the test behaviour and to contribute to the development of design rules for prestressed cable-in-tube systems.
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Reis, Jonathan M. "Structural Concrete Design with High-Strength Steel Reinforcement." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1277124990.
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Olsen, Eric. "Friction stir welding of high-strength automotive steel /." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1911.pdf.
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Olsen, Eric Michael. "Friction Stir Welding of High-Strength Automotive Steel." BYU ScholarsArchive, 2007. https://scholarsarchive.byu.edu/etd/951.
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The following thesis is a study on the ability to create acceptable welds in thin-plate, ultra-high-strength steels (UHSS) by way of friction stir welding (FSW). Steels are welded together to create tailor-welded blanks (TWB) for use in the automotive industry. Dual Phase (DP) 590, 780, and 980 steel as well as Transformation-Induced Plasticity (TRIP) 590 steel with thicknesses ranging from 1.2 mm to 1.8 mm were welded using friction stir welding under a variety of processing conditions, including experiments with dissimilar thicknesses. Samples were tested under tensile loads for initial determination if an acceptable weld had been created. Acceptable welds were created in both TRIP 590 and DP 590 at speeds up to 102 centimeters-per-minute. No acceptable welds were created in the DP 780 and DP 980 materials. A series of microhardness measurements were taken across weld samples to gain understanding as to the causes of failure. These data indicate that softening, caused by both excessive heat and insufficient heat can result in weld failure. Not enough heat causes the high concentration of martensite in these materials to temper while too much heat can cause excessive hardening in the weld, through the formation of even more martensite, which tends to promote failure mode during forming operations. Laser welding is one of the leading methods for creating tailor-welded blank. Therefore, laser welded samples of each material were tested and compared to Friction Stir Welded samples. Lower strength and elongation are measured in weld failure while the failure location itself determines the success of a weld. In short, an acceptable weld is one that breaks outside the weld nugget and Heat Affected Zone (HAZ) and where the tensile strength (both yield and ultimate) along with the elongation are comparable to the base material. In unacceptable welds, the sample broke in the weld nugget or HAZ while strength and elongations were well below those of the base material samples.
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Björklund, Oscar. "Modelling of Failure in High Strength Steel Sheets." Licentiate thesis, Linköpings universitet, Hållfasthetslära, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-77759.
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In this theses the high strength steel Docol 600DP and the ultra high strength steel Docol 1200M are studied. Constitutive laws and failure models are calibrated and veried by the use of experiments and numerical simulations. For the constitutive equations, an eight parameter high exponent yield surface has been adopted, representing the anisotropic behaviour, and a mixed isotropic-kinematic hardening has been used to capture non-linear strain paths. For ductile sheet metals three dierent failure phenomena have been observed: (i) ductile fracture, (ii) shear fracture, and (iii) instability with localised necking. The models for describing the dierent failure types have been chosen with an attempt to use just a few tests in addition to these used for the constitutive model. In this work the ductile and shear fracture have been prescribed by models presented by Cockroft-Latham and Bressan-Williams, respectively. The instability phenomenon is described by the constitutive law and the nite element models. The results obtained are in general in good agreement with test results. The thesis is divided into two main parts. The background, theoretical framework, mechanical experiments and nite element models are presented in the rst part. In the second part, two papers are appended.In publication incorrect ISBN: 9789175198955
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Roenker, Andrew T. "Testing of Torque-and-Angle High Strength Fasteners." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1490701582262578.
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Alcock, J. R. "Magnetic domains in high strength constructional steels." Thesis, University of Leeds, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233698.
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Hardell, Jens. "High temperature tribology of high strength boron steel and tool steels." Licentiate thesis, Luleå : Luleå University of Technology, 2007. http://epubl.ltu.se/1402-1757/2007/36/index.html.
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Oesch, Everett Ralph. "Strength and performance field testing of hybrid HPS bridge A6101 /." free to MU campus, to others for purchase, 2003. http://wwwlib.umi.com/cr/mo/fullcit?p1418053.
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Ghasemi, Rohollah. "Hydrogen-assisted stress corrosion cracking of high strength steel." Thesis, KTH, Skolan för kemivetenskap (CHE), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-50416.
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In this work, Slow Strain Rate Test (SSRT) testing, Light Optical Microscopy (LOM) and Scanning Electron Microscopy (SEM) were used to study the effect of micro-structure, corrosive environments and cathodic polarisation on stress corrosion cracking (SCC) of two grades of high strength steels, Type A and Type B. Type A is manufactured by quench and tempered (Q&T) method. Type B, a normalize steel was used as reference. This study also supports electrochemical polarisation resistance method as an effective testing technique for measuring the uniform corrosion rate. SSRT samples were chosen from base metal, weld metal and Heat Affected Zone (HAZ). SSRT tests were performed at room temperature under free corrosion potential and cathodic polarisation using 4 mA/cm2 in 1 wt% and 3.5 wt% NaCl solutions. From the obtained corrosion rate measurements performed in 1 wt% and 3.5 wt% NaCl solutions it was observed that increased chloride concentration and dissolved oxygen content enhanced the uniform corrosion for all tested materials. Moreover, the obtained results from SSRT tests demonstrate that both Q&T and normalized steels were not susceptible to SCC in certain strain rate(1×10-6s-1) in 1 wt% and 3.5 wt% NaCl solutions under free corrosion potential. It was con-firmed by a ductile fracture mode and high reduction in area. The weld metal of Type A with acicular ferrite (AF), pro-eutectoid (PF) and bainite microstructure showed higher susceptibility to hydrogen assisted stress corrosion cracking compared to base metal and HAZ. In addition, typical brittle intergranular cracking with small reduction in area was observed on the fracture surface of the Type A due to hydrogen charging.
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Rees, Gethin Iorwerth. "Modelling of microstructure in novel high strength steel welds." Thesis, University of Cambridge, 1993. https://www.repository.cam.ac.uk/handle/1810/221884.
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Chen, Ju. "Behaviour of high strength steel columns at elevated temperatures." View the Table of Contents & Abstract, 2007. http://sunzi.lib.hku.hk/hkuto/record/B37206230.
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Donohoe, C. J. "Corrosion fatigue of a high strength low alloy steel." Thesis, University of Sheffield, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322985.
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Murrell, Pamela. "Fatigue and fracture of a high strength cast steel." Thesis, Cranfield University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359549.
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Noury, Pourya. "On failure of high strength steel bridge roller bearings." Doctoral thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-65215.
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This thesis is concerned with failure analysis of high strength steel bridge roller bearings.Paper Adescribes how the commonly used Hertz formulas for contact stresses underestimate the actual stresses in practice due to temperature differences, misalignments and other construction-related conditions. In this paper, finite element analyses of bridge roller bearings were carried out to investigate the accuracy of the traditional roller bearing design rules in view of issues such as girder deformability, misalignment imperfections and material nonlinearity. The results first indicated that roller bearings develop contact stress concentrations at the outer edges of the rollers. Second, it was shown that the contact stresses are very sensitive to misalignment imperfections between the bridge girder and the abutment. Third, it was shown that the roller bearings develop inelastic deformation at relatively low loads in relation to the design load.In Paper B, the finite element method was employed to gain an understanding of the behaviour of a cracked bridge roller bearing in service. The cracked roller was considered as a two-dimensional edge-cracked disk subjected to a diametrical compressive line load. The crack parameters, stress intensity factor Mode I, KI and Mode II ,KII were calculated for the relevant load configuration and angle of disk rotation. The calculated data for KIwere also used to check the accuracy of approximate stress intensity factor solutions reported earlier for Mode I. For plain Mode I loading very good agreement was found between the obtained results and data presented in Schindler and Morf (1994). Paper Cis aimed at finding the likely failure mechanism of a bridge roller bearing made of high strength martensitic stainless steel. Spectroscopy and finite element stress analysis of the roller indicated that an initial radial surface crack, found at an end face of the roller and close to the contact region, was induced by stress corrosion cracking (SCC). The initial crack subsequently changed shape and increased in size under growth through fatigue and finally formed a quarter-circle radial crack centred on the end face corner of the roller. Numerically computed stress intensity factors for the final crack showed that crack loading was predominantly in Mode II. For a crack size as observed on the fracture surface, the maximum service load, as specified by the manufacturer, enhanced by a certain roller bearing misalignment effect, was sufficient for failure through fracture.InPaper D, after a brief summary of the history of high strength stainless steel bearings, the paper reviews service experience of failed bearings in Sweden and elsewhere. Accompanying finite element analyses were performed in order to gain better insight into the likely failure mechanism. Finally, thiscomprehensive review leads to a conclusion that identifies the causes of the failures occurred and makes some recommendations.
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Hartman, Trent J. "Friction Stir Spot Welding of Ultra-High Strength Steel." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3302.
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Friction stir spot welding (FSSW) is quickly becoming a method of interest for welding of high strength steel (HSS) and ultra high strength steel (UHSS). FSSW has been shown to produce high quality welds in these materials, without the drawbacks associated with fusion welding. Tool grade for polycrystalline cubic boron nitride (PCBN) tools has a significant impact on wear resistance, weld quality, and tool failure in FSSW of DP 980 steel sheet. More specifically, for a nominal composition of 90% CBN, the grain size has a significant impact on the wear resistance of the tool. A-type tools performed the best, of the three grades that were tested in this work, because the grain size of this grade was the finest, measuring from 3-6 microns. The effect of fine grain size was less adhesion of DP 980 on the tool surface over time, less abrasive wear, and better lap shear fracture loads of the welds that were produced, compared to the other grades. This is explained by less exposure of the binder phase to wear by both adhesion and abrasion during welding of DP 980. A-type tools were the most consistent in both the number of welds per tool, and the number of welds that reached acceptable lap shear fracture loads. B-type tools, with a bimodal grain size distribution (grain size of 4 – 40 microns) did a little bit better than C-type tools (grain size of 12-15 microns) in terms of wear, but neither of them were able to achieve consistent acceptable lap shear fracture load values after the first 200 welds. In fact only one out of five C-type tools was able to produce acceptable lap shear fracture loads after the first 100 welds.
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Chen, Yujie. "Nominal Shear Strength and Seismic Detailing of Cold-formed Steel Shear Walls using Steel Sheet Sheathing." Thesis, University of North Texas, 2010. https://digital.library.unt.edu/ark:/67531/metadc30444/.
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In this research, monotonic and cyclic tests on cold-formed steel shear walls sheathed with steel sheets on one side were conducted to (1) verify the published nominal shear strength for 18-mil and 27-mil steel sheets; and (2) investigate the behavior of 6-ft. wide shear walls with multiple steel sheets. In objective 1: this research confirms the discrepancy existed in the published nominal strength of 27-mil sheets discovered by the previous project and verified the published nominal strength of 18 mil sheet for the wind design in AISI S213. The project also finds disagreement on the nominal strength of 18-mil sheets for seismic design, which is 29.0% higher than the published values. The research investigated 6-ft. wide shear wall with four framing and sheathing configurations. Configuration C, which used detailing, could provide the highest shear strength, compared to Configurations A and B. Meanwhile, the shear strength and stiffness of 2-ft. wide and 4-ft. wide wall can be improved by using the seismic detailing.
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Sederstrom, Jack Hunter. "Spot friction welding of ultra high-strength automotive sheet steel / /." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1724.pdf.
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Sarma, Abhijit. "High strain properties of advanced high strength spot welded steels." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/5997.
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Thesis (M.S.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 14, 2008) Includes bibliographical references.
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Li, Yang. "Blast Performance of Reiforced Concrete Beams Constructed with High-Strength Concrete and High-Strength Reinforcement." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35261.
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This thesis focuses on the dynamic and static behaviour of reinforced concrete beams built using high-strength concrete and high-strength steel reinforcement. As part of this study, a total of 8 high-strength concrete beams, built with and without steel fibres, and reinforced with high strength ASTM A1035 bars are tested under simulated blast loading using the University of Ottawa shock-tube, with an additional 3 companion beams tested under quasi-static loading. The variables considered in this study include: concrete type, fibre content, steel reinforcement ratio and steel reinforcement type. The behaviour of the beams with high-strength steel bars is compared to a companion set of beams reinforced with conventional steel reinforcement. The criteria used to evaluate the blast performance of the beams includes: overall blast capacity, maximum and residual displacements, secondary fragmentation and crack control. The dynamic results show that high strength concrete beams reinforced with high-strength steel are able to resist higher blast loads and reduce displacements when compared to companion beams with conventional steel reinforcement. The results also demonstrate that the addition of steel fibres is effective in controlling crack formation, minimizing secondary blast fragments, reducing displacements and further increasing overall blast capacity. However, the use of high-strength steel and high-strength concrete also shows potential for brittle failures under extreme blast pressures. The static results show that specimens with high-strength steel bars do not increase beam stiffness, but significantly increase peak load carrying capacity when compared to beams with the same ratio of conventional steel reinforcement. The analytical research program aims at predicting the response of the test beams using dynamic inelastic single-degree-of-freedom (SDOF) analysis and includes a sensitivity analysis examining the effect of various modelling parameters on the response predictions. Overall the analytical results demonstrate that SDOF analysis can be used to predict the blast response of beams built with high-strength concrete and steel reinforcement with acceptable accuracy.
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Dabbagh, Hooshang Civil & Environmental Engineering Faculty of Engineering UNSW. "Strength and ductility of high-strength concrete shear walls under reversed cyclic loading." Awarded by:University of New South Wales. School of Civil and Environmental Engineering, 2005. http://handle.unsw.edu.au/1959.4/27467.
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This study concerns the strength and behaviour of low-rise shear walls made from high-strength concrete under reversed cyclic loading. The response of such walls is often strongly governed by the shear effects leading to the shear induced or brittle failure. The brittle nature of high-strength concrete poses further difficulties in obtaining ductile response from shear walls. An experimental program consisting of six high-strength concrete shear walls was carried out. Specimens were tested under inplane axial load and reversed cyclic displacements with the test parameters investigated being longitudinal reinforcement ratio, transverse reinforcement ratio and axial load. Lateral loads, lateral displacements and the strains of reinforcement in edge elements and web wall were measured. The test results showed the presence of axial load has a significant effect on the strength and ductility of the shear walls. The axially loaded wall specimens exhibited a brittle behaviour regardless of reinforcement ratio whereas the specimen with no axial load had a lower strength but higher ductility. It was also found that an increase in the longitudinal reinforcement ratio gave an increase in the failure load while an increase in the transverse reinforcement ratio had no significant effect on the strength but influenced the failure mode. A non-linear finite element program based on the crack membrane model and using smeared-fixed crack approach was developed with a new aggregate interlock model incorporated into the finite element procedure. The finite element model was corroborated by experimental results of shear panels and walls. The finite element analysis of shear wall specimens indicated that while strengths can be predicted reasonably, the stiffness of edge elements has a significant effect on the deformational results for two-dimensional analyses. Therefore, to capture the deformation of walls accurately, three-dimensional finite element analyses are required. The shear wall design provisions given in the current Australian Standard and the Building Code of American Concrete Institute were compared with the experimental results. The comparison showed that the calculated strengths based on the codes are considerably conservative, specially when there exists the axial load.
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Yang, Jer-Ren. "Development of microstructure in high-strength weld deposits." Thesis, University of Cambridge, 1988. https://www.repository.cam.ac.uk/handle/1810/221894.
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The microstructure of high-strength weld deposits has been investigated using thermodynamic analysis and phase transformation theory, backed by experimental confirmation. The microstructures of both the fusion and reheated zones of multirun alloy-steel weld deposits have been studied. The transformation mechanism of acicular ferrite has been established, and a theory for reaustenitisation in steel weld deposits has also been proposed. In addition to the studies on weld metals, some model alloys were fabricated and tested in order to confirm some of the predictions made by the new theory for reaustenitisation. All the weld metals studied in the investigation possess good hardenability. The primary microstructures of the fusion zone of these deposits consist mainly of acicular ferrite with very little allotriomorphic ferrite.
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Caccialupi, Alessandro. "Systems development for high temperature, high strain rate material testing of hard steels for plasticity behavior modeling." Thesis, Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04082004-180051/unrestricted/caccialupi%5Falessandro%5F200312%5Fms.pdf.
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Qu, Jinbo 1971. "Effect of microstructure on static and dynamic mechanical properties of high strength steels." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103281.
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The high speed deformation behavior of a commercially available dual phase (DP) steel was studied by means of split Hopkinson bar apparatus in shear punch (25m/s) and tension (1000s-1) modes with an emphasis on the influence of microstructure. The cold rolled sheet material was subjected to a variety of heat treatment conditions to produce several different microstructures, namely ferrite plus pearlite, ferrite plus bainite and/or acicular ferrite, ferrite plus bainite and martensite, and ferrite plus different fractions of martensite. Static properties (0.01mm/s for shear punch and 0.001s -1 for tension) of all the microstructures were also measured by an MTS hydraulic machine and compared to the dynamic properties. The effects of low temperature tempering and bake hardening were investigated for some ferrite plus martensite microstructures. In addition, two other materials, composition designed as high strength low alloy (HSLA) steel and transformation induced plasticity (TRIP) steel, were heat treated and tested to study the effect of alloy chemistry on the microstructure and property relationship.A strong effect of microstructure on both static and dynamic properties and on the relationship between static and dynamic properties was observed. According to the variation of dynamic factor with static strength, three groups of microstructures with three distinct behaviors were identified, i.e. classic dual phase (ferrite plus less than 50% martensite), martensite-matrix dual phase (ferrite plus more than 50% martensite), and non-dual phase (ferrite plus non-martensite). Under the same static strength level, the dual phase microstructure was found to absorb more dynamic energy than other microstructures. It was also observed that the general dependence of microstructure on static and dynamic property relationship was not strongly influenced by chemical composition, except the ferrite plus martensite microstructures generated by the TRIP chemistry, which exhibited much better dynamic factor values. This may suggest that solid solution strengthening should be more utilized in the design of crashworthy dual phase steels.
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Linares, Arregui Irene. "Mechanical behaviour of a bainitic high strength roller bearing steel." Licentiate thesis, KTH, Hållfasthetslära (Avd.), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-25423.
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Lord, Michael. "Design and modelling of ultra-high strength steel weld deposits." Thesis, University of Cambridge, 1999. https://www.repository.cam.ac.uk/handle/1810/221873.
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Ellwood, R. D. "Fatigue performance of downgauged high strength steel automotive suspension component." Thesis, Swansea University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636792.
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Work has been carried out to determine whether the weight of a current production suspension component can be reduced, without a reduction in the fatigue performance, through the use of high strength steels and modern welding technologies. The reliability and accuracy of Finite Element (FE) modelling and fatigue prediction techniques have also been investigated. The three steels used in this study, 2.25 mm mild steel, 2.0 mm HSLA and a 1.8 mm dual phase grade showed increasing fatigue performance with tensile strength for unwelded samples. Fusion Metal Active Gas (MAG) welded H-beam samples showed the 2.0mm HSLA material to exhibit better fatigue performance than the mild steel and dual phase materials. Calculating the fatigue lives of these samples using a type F weld from BS7608 significantly overestimated the fatigue performance. Testing the full-scale component biaxially with CARLOS road load data showed the fatigue performance to increase with increasing thickness with the mild steel sample exhibiting a crack length of 5 mm at approximately 3 million km. FE modelling fatigue predictions using a Type F weld curve from BS7608 showed extremely good correlation with the experimental results with an minimum error of only 8% obtained for the mild steel samples.