Dissertations / Theses on the topic 'STEEP ANGLE'
To see the other types of publications on this topic, follow the link: STEEP ANGLE.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'STEEP ANGLE.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Birner, Sabrina Marguerite. "Steep reference angle holography : analysis and applications." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/71398.
Full text
2
Sibold, Ridge Alexander. "The Effect of Density Ratio on Steep Injection Angle Purge Jet Cooling for a Converging Nozzle Guide Vane Endwall at Transonic Conditions." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/102650.
Full textAbstract:
The study presented herein describes and analyzes a detailed experimental investigation of the effects of density ratio on endwall thermal performance at varying blowing rates for a typical nozzle guide vane platform purge jet cooling scheme. An axisymmetric converging endwall with an upstream doublet staggered cylindrical hole purge jet cooling scheme was employed. Nominal exit flow conditions were engine representative and as follows: {rm Ma}_{Exit} = 0.85,
{rm Re}_{Exit,C_{ax}} = 1.5 times {10}^6, and large-scale freestream Tu = 16%. Two blowing ratios were investigated corresponding to the upper and lower engine extrema. Each blowing ratio was investigated amid two density ratios; one representing typical experimental neglect of density ratio, at DR = 1.2, and another engine representative density ratio achieved by mixing foreign gases,
DR = 1.95. All tests were conducted on a linear cascade in the Virginia Tech Transonic Blowdown Wind Tunnel using IR thermography and transient data reduction techniques. Oil paint flow visualization techniques were used to gather quantitative information regarding the alteration of endwall flow physics due two different blowing rates of high-density coolant. High resolution endwall adiabatic film cooling effectiveness, Nusselt number, and Net Heat Flux Reduction contour plots were used to analyze the thermal effects.
The effect of density is dependent on the coolant blowing rate and varies greatly from the high to low blowing condition. At the low blowing condition better near-hole film cooling performance and heat transfer reduction is facilitated with increasing density. However, high density coolant at low blowing rates isn't adequately equipped to penetrate and suppress secondary flows, leaving the SS and PS largely exposed to high velocity and temperature mainstream gases. Conversely, it is observed that density ratio only marginally affects the high blowing condition, as the momentum effects become increasingly dominant. Overall it is concluded density ratio has a first order impact on the secondary flow alterations and subsequent heat transfer distributions that occur as a result of coolant injection and should be accounted for in purge jet cooling scheme design and analysis.
Additionally, the effect of increasing high density coolant blowing rate was analyzed. Oil paint flow visualization indicated that significant secondary flow suppression occurs as a result of increasing the blowing rate of high-density coolant. Endwall adiabatic film cooling effectiveness, Nusselt number, and NHFR comparisons confirm this. Low blowing rate coolant has a more favorable thermal impact in the upstream region of the passage, especially near injection. The low momentum of the coolant is eventually dominated and entrained by secondary flows, providing less effectiveness near PS, near SS, and into the throat of the passage. The high momentum present for the high blowing rate, high-density coolant suppresses these secondary flows and provides enhanced cooling in the throat and in high secondary flow regions. However, the increased turbulence impartation due to lift off has an adverse effect on the heat load in the upstream region of the passage. It is concluded that only marginal gains near the throat of the passage are observed with an increase in high density coolant blowing rate, but severe thermal penalty is observed near the passage onset.Master of Science
3
Kennedy, Richard C. "A Study on the Effect of Jumbo Angles on the Strength and Stiffness of Top-and-Seat Angle Connections." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1416233620.
Full text
4
Gassner, Alexandra Carina. "The character of the core-mantle boundary : a systematic study using PcP." Bachelor's thesis, Universität Potsdam, 2012. http://opus.kobv.de/ubp/volltexte/2013/6359/.
Full textAbstract:
Assuming that liquid iron alloy from the outer core interacts with the solid silicate-rich lower mantle the influence on the core-mantle reflected phase PcP is studied. If the core-mantle boundary is not a sharp discontinuity, this becomes apparent in the waveform and amplitude of PcP. Iron-silicate mixing would lead to regions of partial melting with higher density which in turn reduces the velocity of seismic waves.
On the basis of the calculation and interpretation of short-period synthetic seismograms, using the reflectivity and Gauss Beam method, a model space is evaluated for these ultra-low velocity zones (ULVZs). The aim of this thesis is to analyse the behaviour of PcP between 10° and 40° source distance for such models using different velocity and density configurations. Furthermore, the resolution limits of seismic data are discussed. The influence of the assumed layer thickness, dominant source frequency and ULVZ topography are analysed. The Gräfenberg and NORSAR arrays are then used to investigate PcP from deep earthquakes and nuclear explosions.
The seismic resolution of an ULVZ is limited both for velocity and density contrasts and layer thicknesses. Even a very thin global core-mantle transition zone (CMTZ), rather than a discrete boundary and also with strong impedance contrasts, seems possible: If no precursor is observable but the PcP_model /PcP_smooth amplitude reduction amounts to more than 10%, a very thin ULVZ of 5 km with a first-order discontinuity may exist. Otherwise, if amplitude reductions of less than 10% are obtained, this could indicate either a moderate, thin ULVZ or a gradient mantle-side CMTZ.
Synthetic computations reveal notable amplitude variations as function of the distance and the impedance contrasts. Thereby a primary density effect in the very steep-angle range and a pronounced velocity dependency in the wide-angle region can be predicted. In view of the modelled findings, there is evidence for a 10 to 13.5 km thick ULVZ 600 km south-eastern of Moscow with a NW-SE extension of about 450 km. Here a single specific assumption about the velocity and density anomaly is not possible. This is in agreement with the synthetic results in which several models create similar amplitude-waveform characteristics. For example, a ULVZ model with contrasts of -5% VP-15% VS and +5% density explain the measured PcP amplitudes. Moreover, below SW Finland and NNW of the Caspian Sea a CMB topography can be assumed. The amplitude measurements indicate a wavelength of 200 km and a height of 1 km topography, previously also shown in the study by Kampfmann and Müller (1989). Better constraints might be provided by a joined analysis of seismological data, mineralogical experiments and geodynamic modelling.
Unter der Annahme, dass flüssiges Eisen aus dem äußeren Erdkern mit dem festen, silikat-reichen Unteren Mantel reagiert, wird eine Einflussnahme auf die Kern-Mantel Reflexionsphase PcP erwartet. Ist die Kern-Mantel Grenze aufgeweicht, und nicht wie bislang angenommen ein diskreter Übergang, so zeichnet sich dies in der Wellenform und Amplitude von PcP ab. Die Interaktion mit Eisen führt zu teilweise aufgeschmolzenen Bereichen höherer Dichte, welche die seismischen Wellengeschwindigkeiten herabsetzen. Basierend auf den Berechnungen von kurzperiodischen synthetischen Seismogrammen, mittels der Reflektivitäts- und Gauss Beam Methode, soll ein möglicher Modellraum dieser Niedriggeschwindigkeitszonen ermittelt werden. Das Ziel dieser Arbeit ist es das Verhalten von PcP im Distanzbereich von 10° bis 40° unter dem Einfluss dieser Modelle mit diversen Geschwindigkeits- und Dichtekontrasten zu untersuchen. Ferner wird das Auflösungsvermögen hinsichtlich seismischer Daten diskutiert. Entscheidende Parameter wie Anomaliedicke, Quellfrequenz und Topographie werden hierbei analysiert. Tiefe Erdbeben und Kernexplosionen, die sich im entsprechenden Entfernungsbereich zum Gräfenberg und NORSAR Array befinden, werden anschließend im Hinblick auf PcP ausgewertet. Das seismische Auflösungsvermögen von Niedriggeschwindigkeitszonen ist stark begrenzt sowohl in Bezug auf Geschwindigkeits- und Dichtekontraste als auch hinsichtlich der Mächtigkeit. Es besteht sogar die Möglichkeit einer dünnen, globalen Kern-Mantel Übergangszone, selbst mit großen Impedanzkontrasten, ohne dass dies mit seismologischen Methoden detektiert werden könnte: Wird kein precursor zu PcP beobachtet aber das PcPmodel /PcPsmooth Amplitudenverhältnis zeigt gleichzeitig eine Reduktion von mehr als 10%, dann könnte eine sehr dünne Niedriggeschwindigkeitszone von ca. 5 km Mächtigkeit und einer Diskontinuität erster Ordnung vorliegen. Andererseits, ist PcP um weniger als 10% reduziert, könnte dies entweder auf eine dünne, moderate Niedriggeschwindigkeitszone oder einen graduellen Kern-Mantel Übergang hindeuten. Die synthetischen Berechnungen ergeben starke Amplitudenvariationen als Funktion der Distanz, welche auf den Impedanzkontrast zurückzuführen sind. Dabei ergibt sich ein primärer Dichteeffekt im extremen Steilwinkelbereich und ein maßgeblicher Geschwindigkeitseinfluss im Weitwinkelbereich. Im Hinblick auf die modellierten Resultate lässt sich eine 10 - 13.5 km mächtige Niedriggeschwindigkeitszone 600 km südöstlich von Moskau mit einer NW-SE Ausdehnung von mindestens 450 km folgern, wobei eine exakte Aussage über Geschwindigkeiten und Dichte nicht möglich ist. Dies ist im Konsens mit den synthetischen Berechnungen, wonach viele unterschiedliche Modelle ähnliche Amplituden- und Wellenformcharakteristiken erzeugen. Zum Beispiel erklärt ein Modell mit Kontrasten von -5% VP
-15% VS and +5% Dichte die gemessenen PcP Amplituden. Darüber hinaus können unterhalb des südwestlichen Finnlands und nord-nordwestlich des Kaspischen Meeres Undulationen an der Kern-Mantel Grenze selbst vermutet werden. Unter Berücksichtigung früherer Studien, z. B. von Kampfmann and Müller (1989), deuten die Messergebnisse auf eine laterale Topographie von 200 km und eine Höhe von 1 km hin. Eine Eingrenzung der potentiellen Anomaliemodelle kann nur durch eine gemeinsame Auswertung mit mineralogischen Experimenten und geodynamischen Modellierungen erfolgen.
5
Shani, Mehul A. "Compressive strength of eccentrically loaded steel angles." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0013/MQ52481.pdf.
Full text
6
GAO, XIAOJIANG. "STRENGTH DETERMINATION OF HEAVY CLIP-ANGLE CONNECTION COMPONENTS." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1134401462.
Full text
7
Leong, Chuen Shiong. "Repair/strengthening of steel angles using thermal spray metallizing." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0013/MQ53172.pdf.
Full text
8
Weiner, Stephen (Stephen Andrew). "Design of mechanical testing device to measure break angle of thin, stainless steel." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32969.
Full textAbstract:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.Includes bibliographical references (leaf 25).
Working with Gillette Corporation, an automated mechanical testing tool that bent a small flat piece of steel was designed. The design of the tool was an effort to improve upon previous generations of the same tool. It consisted of three main elements; a servomotor, connected to a torque transducer, which was connected to a break device. A thin piece of steel was loaded into the break device and the motor was activated, moving a flipper arm on the device which bent the steel. While bending this piece of steel, the torque transducer would relay torque and angle information to a computer. This information was collected and displayed in Excel as torque versus angle plots, which would show the moment at which the piece of steel was broken. This entire process was automated so that after loading the steel, one click of a button would run one test. Razorblades were primarily bent with the device until they would break, and for this reason, the measuring tool was called the 'blade break test.' The work consisted of designing a robust mechanical system coupling the three devices mentioned above in series. Code was written in Visual Basic that managed all the individual devices in the measuring tool, getting them to work together and linking them with a computer.
(cont.) A user interface was designed with engineers in mind, imbedding automated data collection and representation through Excel. Finally, a manual was created accompanying the device so other engineers could use, troubleshoot, and modify the 'break test.' The result of this project was the creation of a successful measuring instrument with full documentation and functionality.
by Stephen Weiner.
S.B.
9
Reynolds, Nicholas A. "Behavior and design of concentrically loaded duplex stainless steel single equal-leg angle struts." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/49074.
Full textAbstract:
Stainless steel has garnered attention as an alternative structural material to conventional carbon steel due to its corrosion resistance properties and aesthetic appearance. Of interest are single angles, which are frequently used in trusses, transmission towers, and as bracing diaphragms. When subjected to compression, knowledge concerning the behavior, analysis, and design of stainless steel single angles is very limited.
This thesis addresses the behavior of duplex stainless steel single equal-leg angles subject to concentric compressive loading. Two complementary approaches are used in this study, the first of which was experimental and consisted of conducting 33 full-scale buckling tests on S32003 duplex stainless steel single equal-leg angle components. Angles specimens had slenderness ratios ranging from 35 to 350 and leg width-to-thickness ratios of 7.5 to 12.3. In the second approach, computational models that accounted for material nonlinearity, material anisotropy, and geometric out-of-straightness were developed and validated using the experimentally obtained test results. These models were subsequently used to perform numerical buckling experiments to shed light on the behavior of axially loaded compression duplex stainless steel single angles for a wide range of practical leg width-to-thickness ratios.
Results from the full-scale tests and from the numerical models are shown to correlate well with the classical mechanics-based formulae, which considers nonlinear stress-strain relationships, for predicting flexural and flexural-torsional buckling strengths of singly symmetric stainless steel members. Finally, design criteria in the form of load and resistance factor design (LRFD) with a reliability index of 3 for buckling limit states are proposed for possible adoption in future US national standards.
10
Knobel, Christian. "Optimal control allocation for road vehicle dynamics using wheel steer angles, brake, drive torques camber angles." Düsseldorf VDI-Verl, 2009. http://d-nb.info/992593425/04.
Full text
11
Vlachos, Konstantinos. "A wide angle split-step parabolic equation model for propagation predictions over terrain." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1996. http://handle.dtic.mil/100.2/ADA307444.
Full text
12
Chimezie, Ugochi, and Gurram Akhila Srinivas. "Wetting properties of stainless steel surfaces." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-32598.
Full textAbstract:
Systematic pre cleaning, disinfection and sterilization of medical equipment used in examination and treatment of patients are very important for safe care of the patients and the staff handling these instruments. Due to the technical properties of stainless steel, its hygienic experience and the sophisticated look of the stainless steel, it has dominated the medical health care environments for decades. The wetting properties of stainless steel surfaces are presumed to be essential for the process of clean ability and for a wide variety of bio compatibility.In collaboration with the topical company for this thesis, the idea is to find the correlation between the surface properties of various stainless steel in relation to their wetting and spreading ability to enable efficient cleaning of the surface. For a substrate surface to be thoroughly cleaned of any debris or soil, it should be able to allow proper adherence of the liquid across its surface to a certain degree good enough to ensure good wettability of the surface and conversely easy and proper removal of any attached soil on the surface. Higher demand on cleaning, disinfection and sterilization processes became more and more pressing due the development of complex medical equipment.Different stainless steel (316L) surface finishes and some surgical equipment are investigated using the state of the equipment at Halmstad University. Using the imaging interferometer and mapping software, Mountain Map, the results obtained is controlled readings and classification of the various surface parameters. Contact angle measurements were carried out on each surface with three polar (Distilled water, Glycerol and Ethylene glycol) and one non polar (Olive Oil) probe liquids with a drop volume of 3μm using Theta Optical Tensiometer and One Attention Software for the analysis. The impact and correlations of the surface parameters on wettability was later compared from the measurements obtained.
13
NAGATA, Kazutoshi, Katashi FUJII, Kunitomo SUGIURA, Eiichi WATANABE, Yoshito ITOH, Kuniei NOGAMI, Tetsuya YAMASAWA, et al. "19.5年海洋曝露された鋼アングル材の腐食形態." 土木学会, 2008. http://hdl.handle.net/2237/18831.
Full text
14
Schrauben, Corey S. "Behavior of full-scale bolted beam-to-column T-stub and clip angle connections under cyclic loading." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/20013.
Full text
15
Dock, Melissa. "Influence of pedometer tilt angle on step counting validity during controlled treadmill walking trials." Thesis, Montana State University, 2008. http://etd.lib.montana.edu/etd/2008/dock/DockM0508.pdf.
Full textAbstract:
Pedometers are tools frequently used to monitor walking-related physical activity patterns of overweight and obese populations. However, there is a known association between increasing body mass index (BMI) and decreasing pedometer accuracy. The decrease in pedometer accuracy has been attributed to tilt angle, but the specific tilt angle where pedometers fail to maintain accuracy is unclear. PURPOSE: The purpose of this study was to test two popular pedometer mechanisms, accelerometry- and pendulum-based, to determine the specific tilt angle where the pedometers fail to maintain step counts accurately. METHODS: Twenty subjects (10 men, Mean±SD: 25.4±4.2 yrs, 184.4±5.3 cm, 76.7±6.3 kg; 10 women: 21.6±3 yrs, 166.1±6.3 cm, 56.7±6.7 kg) walked two sets of 21 trials at a combination of treadmill speed (67.0, 80.4, 93.8 m/min) and tilt angle (-30,-20,-10, 0,+10,+20,+30°) while wearing two pedometers; the experimental pedometer attached to a custom-built pedometer gimbal for altering tilt angle, and the control pedometer in a neutral position (±2° of 0°). The pedometers were worn on each hip just anterior to the iliac crest in line with the mid-axillary line of the thigh. The first set of trials tested one pedometer mechanism, while the second set of trials tested the second pedometer mechanism in a counterbalanced order. Mean steps from the experimental pedometer were compared to the control pedometer for each trial (ΔStep=Experimental-Control) using a 3-factor RMANOVA at an alpha level of 0.05. RESULTS: Mean Δsteps for the accelerometry-based pedometer and the pendulum-based pedometer differed significantly (P<0.05) at tilt angles >±10° for treadmill speeds
16
Radhakrishnan, Perumal. "Post-buckled performance of partially restrained and intermediately supported steel angles." PDXScholar, 1986. https://pdxscholar.library.pdx.edu/open_access_etds/3609.
Full textAbstract:
The post-buckled performance of cross-braced single angles was experimentally determined. The results of this study will be used by the Bonneville Power Administration for the analysis of member performance in transmission towers.
17
Hsia, Wei-Kung 1958. "DOUBLE ANGLE CONNECTION MOMENTS (RICHARD EQUATION, PRYING FORCE, BEAM-LINE THEORY, MOMENT ROTATION CURVE)." Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/291892.
Full text
18
Hahnel, Christopher. "Analysis of Bolted Top and Seat Angle Connection Failure Modes & Fracture Prediction." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1447688781.
Full text
19
Tola, Tola Adrian Patricio. "Analytical and Experimental Investigation of Low-Cycle Fatigue Fracture in Structural Steel." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/100051.
Full textAbstract:
The mechanism of metal material failure due to inelastic cyclic deformations is commonly described as Low-Cycle Fatigue (LCF). Fracture in steel structures caused by earthquakes can be associated with this mechanism. Mathematical expressions describing the material deterioration due to LCF are often referred to as LCF laws. The accurate determination of the safety of steel structures against earthquake-induced failure requires the use of LCF laws which have been sufficiently validated with experimental test data.
The present study combined experimental testing and computational simulation to enhance the understanding of structural steel fracture due to LCF. The experiments were conducted in specimens extracted from the flat and corner regions of two rectangular steel hollow sections with different thickness. A total of 60 cylindrical specimens with a circumferential notch were subjected to different combinations of axial and torsional loading. The loading protocols and notch geometry were designed to produce different stress states at the location of fracture initiation. Finite element analyses were conducted to obtain the stress state and inelastic strains at the fracture initiation location. This information was then used for the calibration of five existing LCF laws. The calibration also allowed the comparative evaluation of the capability of the different laws to capture fracture initiation for different stress states, with a single set of values for the various parameters.
The accuracy of the calibrated LCF laws to predict fracture initiation in a large-scale test was also investigated. To this end, a test was conducted on a rectangular steel tube subjected to cyclic axial loading. A finite element analysis of this test was conducted, and predictions of the instant and location of fracture initiation using the calibrated LCF laws were compared with the experimental observations.Doctor of Philosophy
The mechanism of material failure due to repeated cycles of large deformations is denoted as Low-Cycle Fatigue (LCF); this failure mechanism can occur in steel structures subjected to loading conditions such as those induced by earthquakes. Mathematical expressions that evaluate the material deterioration due to LCF are often used to predict the instant and location of fracture initiation in small-scale and large-scale tests. An experimental program was conducted for the study of fracture associated with LCF. A total of 60 specimens were fabricated with material extracted from the flat and corner regions of two rectangular steel tubes; the applied loads elongated and/or twisted the specimens until they ruptured. Computational simulations of these tests were conducted to obtain key information at the location of the observed fracture initiation. This information was used to adjust five mathematical expressions suggested by previous researchers that could predict the same instant of fracture initiation observed in the experiments. The accuracy of the predictions from each of these mathematical expressions was evaluated. The accuracy of these mathematical expressions to predict fracture initiation in a large-scale test was also investigated. To this end, an experiment was conducted on a rectangular steel tube subjected to repeated cycles of deformation. A computational simulation of this test was also developed, and predictions of the instant and location of fracture initiation were compared with the experimental observations.
20
HagenBurger, William C. "Feasibility of open web rafters constructed of single angles." Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/42069.
Full textAbstract:
The purpose of the research reported here was to determine if single angles can be used for
chord and web members in lightweight steel open web rafters, and if so to determine what effect
the single angles have on the design of the rafter's members. A computer model was constructed
to determine the effects of a unsymetric cross section coupled with eccentric loadings of the
members on out-or-plane displacements, and bending moments and stresses in the chord and web
members. This computer model modeled the eccentricities and unsymetric section properties of
the single angles. A study of the effect of out-or-plane bracing on the bending moments and
stresses was also conducted. Finally various web configurations (angle web members on the same
side, alternating, and opposite) were studied to determine their effect on moments in the web and
chord members, along with their effect on out-or-plane displacements. A preliminary design
procedure for chord and web members using the new AISC ""Specification For Allowable Stress
Design of Single Angle Members" is presented. Finally suggestions on out-of-plane bracing and
connections are made.
Master of Science
21
Yip, Amy Sin-Man. "Shear lag in bolted cold-formed steel angles and channels in tension." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0014/MQ59908.pdf.
Full text
22
Yan, Zhishan. "Shear and Compression Strength of Cold-formed Steel Clip Angles Subjected to Different Screw Patterns." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc1062892/.
Full textAbstract:
This thesis presents experiments and numerical analysis of the cold-formed steel clip angle in three different limit states which are shear, compression, and combination of the screw connection. A previous cold-formed steel clip angle test program (which is Phase 1) developed design methods for clip angle. Therefore, the object of this thesis is to further investigate the behavior and design methods of loading-bearing cold-formed steel clip angles under different screw pattern. For each limit state, a test program was conducted to investigate the behavior, strength, and deflection of the clip angle. The test result were compared with previous CFS clip angle design method. Amending existing CFS clip angle method were developed by each of the four limit states studied in this project.
23
Kartha, Aravind, and Shravan Subramanian. "Turning of tool steel : Study on the effect of insert grade and entering angle on tool life." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-281530.
Full textAbstract:
PrimeTurning™ is a new turning technology, which consists of tools and programming method. By using this method, it has been demonstrated that higher material removal rates and flexibility in turning can be obtained. The New Product Industrialisation department at AB Sandvik Coromant works with development of production processes and improvements in current processes.Machining tests are carried out in order to improve production performance, and find optimised solutions. In this master thesis work, the effect of insert grades and entering angles on wear and tool life while machining hardened tool steel has been studied. Machining experiments have been carried out to analyse wear and tool life by using the PrimeTurning™ method.Two approaches of experimental design have been investigated, and a suitable design is selected for conducting the experiments. The performance of these insert grades and tool holders (κ=21° and κ=25°) has been compared to each other and the existing production scenario, and a recommendation is made regarding insert grade,tool holder and cutting parameter selection for machining hardened tool steel using PrimeTurning™. The wear analysis has been performed by using a stereo microscope coupled with an image processing software to measure the flank wear length. Flank wear, flaking and chipping have been observed as the major wear types. As a result, it has been identified that the insert grade GXXC, coupled with the tailor-made tool holder performs significantly better than the currently used insert and tool holder in production. A substantial increase in tool life increase is observed, even when machining at a higher Material Removal Rate of 29%. This would result in a significant increase productivity, if the results can be reproduced in production.PrimeTurning ™ är en ny svarvningsteknik som består av verktyg och programmeringsmetod. Genom att använda denna metod har det visats att högre materialavlägsningshastigheter och flexibilitet vid svarvning kan uppnås. Avdelningen för nyproduktionsindustrialisering på AB Sandvik Coromant arbetar med utveckling av produktionsprocesser och förbättringar av nuvarande processer. Maskintester genomförs för att förbättra produktionsprestanda och hitta optimerade lösningar I det här examensarbetet som utförts vid AB Sandvik Coromant har effekten av skärsorter och ställvinklar på slitage och livslängd vid bearbetning av härdat verktygsstål studerats. Maskinbearbetningsexperiment har utförts för att analysera slitage och verktygslivslängd med hjälp av PrimeTurning ™ -metoden. Två metoder för experimentell design har undersökts och en lämplig design väljs för att utföra experimenten. Prestandan hos dessa skärsorter och verktygshållare (κ = 21 ° och κ = 25 °) har jämförts med varandra och det nuvarande produktionsscenariot, och en rekommendation görs beträffande skärsort, verktygshållare och val av skärparametrar för maskinbearbetning av verktygsstål med PrimeTurning ™. Förslitningsanalysen har utförts med användning av ett stereomikroskop kopplat till en bildbehandlingsprogramvara för att mäta längden av fasförslitningen. Fasförslitning, urflisning och flagning har observerats som de viktigaste typerna av förslitning. Studiens resultat visar att skäret GXXC, i kombination med den skräddarsydda verktygshållaren presterar avsevärt bättre än det för närvarande använda skäret och verktygshållaren i produktionen. En kraftig ökning av livslängden på verktyg observeras även vid bearbetning med en högre Spånavverkningshastighet på 29%. Om dessa resultat kan reproduceras i produktionen kan en betydande produktivitetsökning erhållas.
24
Martin, Brandi Nichole. "A comparison of double clip angle shear connections to shear tab connections in industrial applications." Kansas State University, 2017. http://hdl.handle.net/2097/35552.
Full textAbstract:
Master of ScienceDepartment of Architectural Engineering
Kimberly W. Kramer
In structural steel connection design, simple shear connections are one of the most common connection types utilized. The industry, especially from the side of the engineer, tends to lean toward using Double Clip Angle Connections as the default standard for simple shear connections. A double clip angle connection is a connection consisting of two angles transferring the shear forces from one member to the next either through bolts or welds. The design of Double Clip Angle Connections is efficient and the connections themselves are easy to fabricate. However, benefits to utilizing other types of shear connections exist. Many of these benefits are seen in the fabrication shop or during erection and construction. This is especially true of single shear plate or shear tab connections when applied to open structure design. Shear tab connections consist of a single plate that transfers the shear forces from one member to the next with bolts or with welds. The design of shear tab connections can be a more involved process than the design of double clip angles. Sometimes the shear plate or shear tab has to be longer than is typical. This is called an extended shear plate connection. These extended shear plates can bring other variables into the design that typically don’t occur with Double Clip Angle Connections such as bending of the plate or the need for multiple bolt columns. However, with proper planning and detailing, the benefits and savings experienced in the fabrication or construction phase may outweigh what can be seen as a more laborious design task. The purpose of this report is to identify the possible benefits achieved in using each of these connections, highlight the differences in the design approach for each, and use a study model to compare the outcome of using one connection over another in the design of a typical open structure. Double clip angles are typically the most efficient approach when speed of design and simplicity of fabrication are the desired outcomes. However, shear plate or shear tab connections have the potential to provide safer erection alternatives and materials savings if used in appropriate ways and with the right applications.
25
Haidar, Raymond. "Compressive strength of steel single angles loaded through two-bolts in one leg." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ30871.pdf.
Full text
26
Dalvi, Vikrant Vijay. "Walls: Exploring the layers of a building." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/79685.
Full textAbstract:
Wall, traditionally an enclosing element in architecture, has been used throughout the ages for functions like privacy, protection, definition of spaces, and also to provide attractive facades.
Visually walls can be more than a mere static element. Over time, attempts have been made by various architects to explore and redefine the role of a wall as an architectural element. The wall can enhance, adorn, aggrandize, beautify, embellish......
My thesis aims at exploring the role of a wall in a building and moving beyond the boundaries of its primary functions. The wall in this project is a multi-layered , transparent, clear and lucid enclosure wrapping the inner solids.
The idea is to have solid and opaque geometrical planes and volumes as inner cores and masking these with an outer envelope of double-glass and steel.
The study delves further into the interaction between the three assemblies.Master of Architecture
27
Lu, Jian. "Microstructure Evolution in 304L Stainless Steel Subjected to Hot Torsion at Elevated Temperature." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2854.
Full textAbstract:
The current study focus on investigating a relationship between processing variables and microstructure evolution mechanism in 304L stainless steel subjected to hot torsion. The Gleeble 3800 with Mobile Torsion Unit (MTU) is utilized in the current study to conduct hot torsion test of 304L stainless steel. Samples are rotated at 1100℃ in the shear strain rate range of 0.02s-1 to 4.70s-1 and the shear strain range of 0.5 to 4. Orientation imaging microscopy (OIM) technique is used to collect and analyze the microstructure. At low strains (≤1) and strain rate (0.02s-1), average grain size remains relatively constant, but the lengths of DSs and LABs increase within grains. These are characteristics of the dynamic recovery (DRV). With increasing strain and strain rate, the lengths of DSs, LABs and HABs increase, accompanied by the decrease of average grain size. Subgrains with HAB segments are observed. These are characteristics of continuous dynamic recrystallization (CDRX). At strain rates greater than or equal to 0.94s-1, the fraction of deformation texture is about 3 times higher than that of rotated cube texture. The average grain size increases relative to that at a strain rate of 0.20s-1, accompanied by the increase of twin length per area. This indicates that grain growth take place after CDRX. Sigma phase is not observed in the current study due to the lack of static recrystallization (SRX) and the higher cooling rate.
28
Bedekar, Vikram. "Nanostructural Evolution of Hard Turning Layers in Carburized Steel." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366195383.
Full text
29
Ejenstam, Lina. "Hydrophobic and superhydrophobic coatings for corrosion protection of steel." Doctoral thesis, KTH, Yt- och korrosionsvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-175405.
Full textAbstract:
Since metals in general, and steels in particular, are vital construction materials in our modern society, the corrosion protection of said materials is of great importance, both to ensure safety and to reduce costs associated to corrosion. Previously, chromium (VI) and other harmful substances were effectively used to provide corrosion protection to steel, but since their use was heavily regulated around year 2000, no coating has yet been developed that, in a fully satisfactory manner, replaces their corrosion protective properties.In this thesis, the use of hydrophobic and superhydrophobic surface coatings as part of corrosion protective coating systems has been studied. Since the corrosion mechanism relies on the presence of water to take place, the use of a superhydrophobic coating to retard the penetration of water to an underlying metal surface is intuitive. The evaluation of corrosion protective properties of the hydrophobic and superhydrophobic surfaces was performed using mainly contact angle measurements and electrochemical measurements in severely corrosive 3 wt% NaCl water solution.First, the differences in corrosion protection achieved when employing different hydrophobic wetting states were investigated using a model alkyl ketene dimer wax system. It was found that superhydrophobicity in the Lotus state is superior to the other states, when considering fairly short immersion times of less than ten days. This is due to the continuous air film that can form between such a superhydrophobic surface and the electrolyte, which can retard the transport of electrolyte containing corrosive ions to the metal surface to the point where the electrical circuit is broken. Since corrosion cannot occur unless an electrical current is flowing, this is a very efficient way of suppressing corrosion.An air layer on an immersed superhydrophobic surface is, however, not stable over long time, and to investigate long-term corrosion protection using hydrophobic coatings a polydimethylsiloxane formulation containing hydrophobic silica nanoparticles was developed. This system showed enhancement in corrosion protective properties with increasing particles loads, up until the point where the particle load instead causes the coating to crack (at 40 wt%). The conclusion is that the hydrophobicity of the matrix and filler, in combination with the elongatedivdiffusion path supplied by the addition of particles, enhanced the corrosion protection of the underlying substrate.To further understand how hydrophobicity and particle addition affect the corrosion protective properties of a coating a three layer composite coating system was developed. Using this coating system, consisting of a polyester acrylate base coating, covered by TiO2 particles (with diameter < 100 nm) and finally coated with a thin hexamethyl disiloxane coating, it was found that both hydrophobicity and particles are needed to reach a great enhancement in corrosion protective properties also for this system.Eftersom metaller, och då särskilt stål, är viktigta konstruktionsmaterial i vårt moderna samhälle är korrosionsskydd av stor betydelse, både för att garantera säkerhet och för att minska kostnader som uppkommer i samband med korrosion. Tidigare har sexvärt krom och andra skadliga ämnen använts för att på ett effektivt sätt skydda stål från korrosion, men efter att deras användning kraftigt reglerades runt år 2000 har ännu ingen beläggning utvecklats som helt kan ersätta krombeläggningarna med avseende på funktion.I denna avhandling har hydrofoba och superhydrofoba ytbeläggningar och deras möjliga applikation som en del av ett korrosionsskyddande beläggningssystem studerats. Eftersom korrosionsmekanismen är beroende av närvaron av vatten, är användandet av en superhydrofob beläggning för att fördröja transporten av vatten till den underliggande metallytan intuitiv. De korrosionsskyddande egenskaperna hos superhydrofoba ytbeläggningar utvärderades här främst med hjälp av kontaktvinkelmätningar och elektrokemisk utvärdering i korrosiv lösning bestående av 3 vikts% NaCl i vatten.Först undersöktes skillnaden i korrosionsskydd som uppnås vid användandet av ytbeläggningar med olika hydrofoba vätningsregimer med hjälp av ett modellsystem bestående av ett alkylketendimer vax. Det konstaterades att superhydrofobicitet i Lotusregimen är överlägset bättre än de andra hydrofoba vätningsregimerna, i alla fall när man ser till relativt korta exponeringstider, typiskt mindre än tio dagar. Detta beror på att den kontinuerliga luftfilm som kan bildas på en sådan typ av superhydrofob yta kan minska transporten av elektrolyt (som innehåller korrosiva joner) till metallytan till den grad att den elektriska kretsen bryts. Eftersom korrosion inte kan ske utan en sluten elektrisk krets är detta ett mycket effektivt sätt att förhindra korrosion från att ske.Ett luftskikt på en superhydrofob yta nedsänkt i vatten är dock inte stabilt under lång tid. För att undersöka möjligheten till korrosionsskydd under längre tid med hjälp av hydrofoba beläggningar utvecklades en hydrofob ytbeläggning bestående av polydimetylsiloxan och hydrofoba nanopartiklar av kiseldioxid. Detta system visade en förbättring av korrosionsskyddet vid ökat partikelinnehåll upp till den koncentration (40 wt%) där i stället sprickbildning i ytbeläggningen observerades. Från detta system kunde slutsatsen dras att matrisens och partiklarnasvihydrofobicitet i kombination med den längre diffusionsvägen som partiklarna orsakade förbättrade korrosionsskyddet av den underliggande metallen.För att ytterligare förstå hur hydrofobicitet och partikeltillsatser påverkar en ytbeläggnings korrosionsskyddande egenskaper har dessutom ett treskikts kompositbeläggningssystem utvecklats. Genom att använda detta beläggningssystem, som består av en basbeläggning av polyesterakrylat, ett lager TiO2-partiklar (med en diameter på <100 nm) slutligen belagt med ett tunt ytskikt bestående av hexametyldisiloxan så kunde slutsatsen dras att både en hydrofob matris och partiklar behövs för att nå en markant förbättring av ytbeläggningens korrosionsskyddande egenskaper.
QC 20151015
30
Johansson, Robert. "Finite element modeling of straightening of thin-walled seamless tubes of austenitic stainless steel." Thesis, Högskolan Dalarna, Materialteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:du-21463.
Full textAbstract:
During this thesis work a coupled thermo-mechanical finite element model (FEM) was builtto simulate hot rolling in the blooming mill at Sandvik Materials Technology (SMT) inSandviken. The blooming mill is the first in a long line of processes that continuously or ingotcast ingots are subjected to before becoming finished products. The aim of this thesis work was twofold. The first was to create a parameterized finiteelement (FE) model of the blooming mill. The commercial FE software package MSCMarc/Mentat was used to create this model and the programing language Python was used toparameterize it. Second, two different pass schedules (A and B) were studied and comparedusing the model. The two pass series were evaluated with focus on their ability to healcentreline porosity, i.e. to close voids in the centre of the ingot. This evaluation was made by studying the hydrostatic stress (σm), the von Mises stress (σeq)and the plastic strain (εp) in the centre of the ingot. From these parameters the stress triaxiality(Tx) and the hydrostatic integration parameter (Gm) were calculated for each pass in bothseries using two different transportation times (30 and 150 s) from the furnace. The relationbetween Gm and an analytical parameter (Δ) was also studied. This parameter is the ratiobetween the mean height of the ingot and the contact length between the rolls and the ingot,which is useful as a rule of thumb to determine the homogeneity or penetration of strain for aspecific pass. The pass series designed with fewer passes (B), many with greater reduction, was shown toachieve better void closure theoretically. It was also shown that a temperature gradient, whichis the result of a longer holding time between the furnace and the blooming mill leads toimproved void closure.
31
Bartolotta, Simona <1996>. "Minds of Steel: Imagination and Detection in Isaac Asimov's Robot Novels and Short Stories." Master's Degree Thesis, Università Ca' Foscari Venezia, 2020. http://hdl.handle.net/10579/17666.
Full textAbstract:
Isaac Asimov has been singled out by SF scholars as the author who legitimized the SF mystery subgenre, which typically unfolds a detective fiction plot in an SF context. Nowhere is this hybridizing tendency more evident than in the Robot series, comprised of four full-length novels and several short stories. This thesis argues that Asimov’s pairing of SF and mystery reflects the typical dialectical movement displayed in all his fiction, which proceeds by setting up oppositions between apparently antithetical terms (past/future, logic/intuition, human/robot) which are eventually shown to reach a synthesis. After a section that traces the genesis and evolution of the Asimovian robot, the following chapters focus each on one of these thematic pairs, and demonstrate how Asimov’s robot fiction engages with the theory of SF, the history of detective fiction, and branches of science such as cybernetics. This analysis ultimately reveals that the variety of the Robot stories serves not to invite an evaluative comparison between humans and robots, but rather to explore as extensively as possible Asimov’s underlying preoccupation with the workings of intelligence, be it human or robotic.
32
Romаnszki, L., M. Mohos, J. Telegdi, and L. Nyikos. "Contact Angle Measurement is an Efficient Tool for the Characterization of Corrosion Pro-tection Nanolayers on Copper Alloys and Stainless Steel." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35254.
Full textAbstract:
With the advent of the nano-era, a pronounced interest in the nanolayers has emerged. The develop-ment of more and more sophisticated measurement devices and techniques made possible the visualiza-tion, characterization and investigation of nanolayers. However, there exists a variety of simple, old means which should not be despised either. In this work, the use of contact angle measurement as a simple, fast, inexpensive and accessible tool for the study of surfaces with and without nanolayers is demonstrated. Furthermore, it is evidenced that in contrast to its simplicity, contact angle measurement can address sur-prisingly complex questions and give proper answers to these.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35254
33
Liu, Yanyan. "NONLINEAR DYNAMICS CHARACTERIZATION OF BIDIRECTIONAL SEISMIC RESPONSE OF STEEL BRIDGE PIERS." Kyoto University, 2018. http://hdl.handle.net/2433/232023.
Full text
34
Hornbeak, Christopher James. "Mechanical Characterization of Selectively Laser Melted 316L Stainless Steel Body Centered Cubic Unit Cells and Lattice of Varying Node Radii and Strut Angle." DigitalCommons@CalPoly, 2018. https://digitalcommons.calpoly.edu/theses/1883.
Full textAbstract:
An experimental study of several variants of radius and strut angle of the body centered cubic unit cell was performed to determine the mechanical properties and failure mechanisms of the mesostructure. Quasi static compression tests were performed on an Instron® universal testing machine with a 50kN load cell at 0.2mm/min. The test samples were built using a SLM Solutions 125 selective laser melting machine with 316L stainless steel. Test specimens were based on 5mm cubic unit cells, with a strut diameter 10% of the unit cell size, with skins on top and bottom to provide a cantilever boundary constraint. Specimens were inspected for dimensional accuracy using precision calipers and inspected for morphology using a MicroVu® macroscope. The compressive properties of the mesostructure was compared to the compressive properties of macrostructure. The BCC unit cell behaves significantly different at the boundary layer of a constrained lattice. The failure mode at the boundary is characterized by plastic bending within the microstruts while the non boundary layer cells fail via plastic bending at the node. Manufacturing compensation parameters were determined for part shrinkage and droop. Two predictive numerical models were developed, based on the Gibson-Ashby model of cellular solids, as well as a finite element model. Numerical results did not agree well with the experimental results, indicating that the droop observed on the structures significantly affects the mechanical properties of the overall structure. The 25% radius cubic unit cell and 3^3 lattice withstood the greatest stress of all specimens tested and exhibited nearly ideal plastic deformation behavior.
35
Van, Eyssen Juanita. "A new method of utilising stability study results in applying out-of-step protection to allow observability of rotor angle unstable conditions." Doctoral thesis, University of Cape Town, 1999. http://hdl.handle.net/11427/22487.
Full textAbstract:
Power system rotor-angle unstable conditions may cause undesired operation of distance relays, resulting in the unnecessary switching of lines. To prevent the possible undesired operation of distance relays, a protection type known as out-of-step blocking is used. This protection type is complemented by another type of protection, known as out-of-step tripping protection. The tripping protection's main functions are to detect total loss of synchronism and send tripping signals to selected locations in the system to initiate islanding. In this research the application of out-of-step blocking and tripping protection was investigated. The motivation for the research was provided by system unstable incidents that occurred in Eskom, the electricity utility of South Africa. Detailed out-of-step protection investigations indicated that the out-of-step blocking and tripping protection applied according to a method which is based on an existing approach failed to detect the unstable conditions. In summary, the detailed investigations showed that the existing approach of applying out-of-step blocking and tripping protection is not adequate as it does not allow the necessary observability1 and correct detection of rotor-angle unstable conditions.
36
Tang, Xuanping. "Effect of Surface State on Water Wetting and Carbon Dioxide Corrosion in Oil-water Two-phase Flow." Ohio University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1304638556.
Full text
37
Maia, Wanderson Fernando. "Análise teórica e experimental de barras em dupla cantoneira de aço formada a frio submetidas à compressão." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-10102012-083428/.
Full textAbstract:
Barras compostas em dupla cantoneira são constituídas por duas seções idênticas dispostas paralelamente, afastadas entre si e ligadas uma a outra apenas em alguns pontos ao longo do comprimento, por meio de chapas separadoras. O sistema aqui apresentado é bastante utilizado, principalmente em estruturas treliçadas leves, no entanto, não existem estudos específicos sobre seu comportamento, como conseqüência as normas de cálculo não fornecem subsídios para o projeto desse componente estrutural. É relevante estudar o comportamento de barras em dupla cantoneira, já que neste caso, além dos modos de instabilidade associados à cantoneira isolada, poderão ocorrer modos de instabilidade associados à barra composta em função da presença das chapas separadoras, que tendem a modificar o comportamento do sistema. Apresenta-se no trabalho análises numérica e experimental sobre o comportamento de barras submetidas à compressão centrada e excêntrica. Nas análises variou-se o número de chapas separadoras buscando estudar a eficiência das mesmas na força normal resistente das barras. Os resultados mostraram que a introdução de chapas separadoras melhorou significativamente o comportamento das barras, principalmente para compressão excêntrica. Foram observados modos de instabilidade por flexo-torção, por flexão e combinação dos dois modos. Para comparação dos resultados, inicialmente foram adotadas duas hipóteses de cálculo com base no procedimento da ABNT NBR 14762:2010, considerando compressão centrada. No primeiro procedimento considerou-se cada cantoneira como uma barra isolada independente da presença das chapas separadoras, admitiu-se instabilidades local, por flexo-torção e por flexão; no segundo considerou-se barra composta admitindo-se apenas instabilidades local e por flexão em relação ao eixo principal de menor inércia do conjunto. Em geral, os resultados das análises numérica e experimental apresentaram valores intermediários aos obtidos pelas duas hipóteses adotadas inicialmente. Com os resultados obtidos nas análises numérica e experimental são recomendados procedimentos para o dimensionamento desse componente estrutural.Double-angle members with batten plates consist of two identical angles set up in parallel, spaced apart, and connected to each other by batten plates at specified points along the length. The system presented herein is widely used, especially in light truss structures; however, there are no standard design procedures specific for the design of this structural component. Studying the behavior of double angle members is interesting, because in this case, besides the critical modes of the single angle, they also show critical modes, due to the presence of the batten plates that sometimes interfere with the behavior of the system. This work presents a numerical and experimental study of members under concentric and eccentric axial compression. The number of batten plates is changed to study the influence on the nominal axial strength. The use of batten plates significantly increases the strength of the system, especially for members under eccentric compression. The buckling modes observed were flexural-torsional, flexural and combination of the modes. Initially, two design hypotheses are compared to the results obtained: (i) non-composite action (no interaction between angles), with only local, flexural, and flexural-torsional buckling considered; (ii) composite action (full interaction between angles), and only considering local and minor-axis flexural buckling of the pair of angles. The two design hypotheses ignore load eccentricity. The hypotheses are based upon recommendations in ABNT NBR 14762:2010. In general, numerical and experimental results for angles connected by bolted batten plates fall in between the design curves defined by methods (i) and (ii). With the results obtained in numerical and experimental analysis, procedures are recommended for the design of this structural component.
38
Couturier, Laurent. "Caractérisation des évolutions microstructurales de l'acier inoxydable martensitique à durcissement structural 15-5PH au cours du vieillissement thermique." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENI045/document.
Full textAbstract:
L’acier inoxydable martensitique durci par précipitation 15-5PH est utilisé dans le domaine del’aéronautique comme matériau constitutif des pièces liant les réacteurs aux ailes, il est ainsi soumisen utilisation à des températures de l’ordre de 300°C, ce qui entraine sa fragilisation. Cettefragilisation des aciers inoxydables dans ce domaine de températures est causée par la démixtion dufer et du chrome, principaux constituants de la matrice, par décomposition spinodale. De plus, lamicrostructure complexe du 15-5PH contient également des précipités de cuivre assurant ledurcissement initial de l’alliage, de l’austénite de réversion, connue dans ce type d’aciers pourapporter un regain de ductilité, apparaissant lors du traitement de précipitation du cuivre et de laphase G apparaissant au cours du vieillissement. L’évolution de ces phases pourrait égalemententrainer une modification des propriétés mécaniques de l’alliage. Pour observer les différentesévolutions de la microstructure nous avons utilisé une combinaison de techniques apportant desinformations complémentaires afin d’en obtenir une caractérisation la plus complète possible. Nousavons ainsi pu montrer que les modifications de propriétés sont causées par la décompositionspinodale de la matrice. L’évolution de ses caractéristiques microstructurales a pu être décrite pardes lois phénoménologiques, fonctions de la durée et de la température de vieillissement. Nousavons également pu fournir une méthode permettant la mesure indirecte de l’avancée duvieillissement du 15-5PH, validée par les observations microstructurales, ainsi qu’un modèlephénoménologique permettant de prévoir la dureté de l’alliage.Mots clés : acier martensitique, décomposition spinodale, vieillissement, diffusion aux petits angles,sonde atomique tomographique, calorimétrie différentielle à balayageThe precipitation hardened martensitic stainless steel grade 15-5PH is used in the airplane industryas constitutive material of parts joining reactors to wings. Due to its application it is subjected totemperatures around 300°C leading to its embrittlement. Stainless steels embrittlement in thistemperature range is due to iron-chromium unmixing by spinodal decomposition. In addition, the 15-5PH grade has a complex microstructure comprising copper precipitates responsible for the initialhardening of the alloy, reversed austenite, known in this kind of steels to improve the toughness,which appears during the precipitation thermal treatment and G phase that precipitates duringaging. The evolutions of these microstructure components could also lead to some modifications ofthe material mechanical properties. In order to study the microstructure evolutions we use acombination of characterization techniques aiming at their most complete description. We show thatthe mechanical properties evolution is controlled by the spinodal decomposition of the matrix whoseevolution we are able to depict by simple phenomenological laws. We propose an indirect methodfor the measurement of aging kinetics of the 15-5PH steel, which we have correlated to directmeasurements, and a phenomenological law allowing the prediction of the alloy hardness based onits thermal history
39
Blakelock, Eleanor S. "The Early Medieval Cutting Edge of Technology: An archaeometallurgical, technological and social study of the manufacture and use of Anglo-Saxon and Viking iron knives, and their contribution to the early medieval iron economy." Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/5517.
Full textAbstract:
A review of archaeometallurgical studies carried out in the 1980s and 1990s of early medieval (c. AD410-1100) iron knives revealed several patterns, with clear differences in knife manufacturing techniques present in rural cemeteries and later urban settlements. The main aim of this research is to investigate these patterns and to gain an overall understanding of the early medieval iron industry. This study has increased the number of knives analysed from a wide spectrum of sites across England, Scotland and Ireland. Knives were selected for analysis based on x-radiographs and contextual details. Sections were removed for more detailed archaeometallurgical analysis.
The analysis revealed a clear change through time, with a standardisation in manufacturing techniques in the 7th century and differences between the quality of urban and rural knives. Analysis of cemetery knives revealed that there was some correlation between the knife and the deceased. Comparison of knives from England, Dublin and Europe revealed that the Vikings had little direct impact on England¿s knife manufacturing industry, although there was a change in manufacturing methods in the 10th century towards the mass produced sandwich welded knife. This study also suggests that Irish blacksmiths in Dublin continued their ¿native¿ blacksmithing techniques after the Vikings arrived. Using the data gathered a chaîne opértoire of the iron knife was re-constructed, this revealed that there was a specific order to the manufacture process and decisions were not only influenced by the cost of raw materials, the skill of the blacksmith and the consumer status, but also by cultural stimulus.
40
Nascimento, Andr? Ezequiel Gomes do. "Avalia??o da molhabilidade de solu??es de tensoativos em a?o inoxid?vel." Universidade Federal do Rio Grande do Norte, 2009. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15781.
Full textAbstract:
Made available in DSpace on 2014-12-17T15:01:21Z (GMT). No. of bitstreams: 1
Andre_sem_Cap234567.pdf: 796852 bytes, checksum: ae985c95250c45acc8aaa9d33c06b2bb (MD5)
Previous issue date: 2009-09-04Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico
With the increasing industrialization of the planet caused by globalization, it has become increasingly common to search for highly resistant and durable materials for many diverse branches of activities. Thus, production and demand for materials that meet these requirements have constantly increased with time. In view of this, stainless steel is presented as one of the materials which are suitable applications, due to many features that are interesting for several segments of the industry. Concerns of oil companies over heavy oil reservoirs have grown steadily for the last decades. Rheological properties of these oils impair their transport in conventional flow systems. This problem has created the need to develop technologies to improve flow and transport, reducing operation costs so as to enable oil production in the reservoir. Therefore, surfactant-based chemical systems are proposed to optimize transport conditions, effected by reduction of interfacial tensions, thereby enhancing the flow of oil in ducts and reducing load losses by friction. In order to examine such interactions, a study on the wettability of metallic surfaces has been undertaken, represented by measuring of contact angle of surfactant solutions onto flat plates of 304 stainless steel. Aqueous solutions of KCl, surfactants and mixtures of surfactants, with linear and aromatic hydrocarbon chain and ethoxylation degrees ranging between 20 to 100, have been tested. The wettability was assessed by means of a DSA 100 kr?ss goniometer. The influence of roughness on the wettability was also investigated by machining and polished the stainless steel plates with sandpapers of references ranging between 100 of 1200. The results showed that sanding and polishing plates result in decrease of wettability. As for the solutions, they have provided better wettability of the stainless steel than the KCl solutions tested. It was also been concluded that surfactant mixtures is an option to be considered, since they promote interactions that generate satisfactory contact angles for a good wettability on the stainless steel plate. Another conclusion refers to the influence of the ethoxylation degree of the nonionic surfactant molecules on wettability. It has been observed that contact angles decrease with decreasing ethoxylation degrees. This leads us to conclude that molecules with higher ethoxylation degree, being more hydrophobic, decrease the interaction of water with the ducts, thereby reducing friction and improving the flow
Com o crescente aumento da industrializa??o, provocado pela globaliza??o do planeta, tornou-se cada vez mais comum a busca por materiais de alta resist?ncia e durabilidade para os mais diversificados ramos de atividades. Assim, a produ??o e procura por materiais que atendam estas exig?ncias tornou-se cada vez maior com o passar dos anos. Logo, um dos materiais que v?m preenchendo bem os requisitos necess?rios para esta aplica??o ? o a?o inoxid?vel, devido ?s suas diversas caracter?sticas aplic?veis aos diferentes ramos da ind?stria. O interesse das companhias de petr?leo por reservas de ?leos pesados vem apresentando aumento constante durante as ?ltimas d?cadas. As propriedades reol?gicas destes ?leos impedem o seu transporte em sistemas convencionais de fluxo. A partir deste problema surge a necessidade do desenvolvimento de tecnologias que permitam melhorar o escoamento e transporte, reduzindo os custos de opera??o, para, assim, viabilizar a produ??o de ?leo no reservat?rio. Diante disto, surge o transporte atrav?s de sistemas contendo tensoativos, que reduzem as tens?es interfaciais, facilitando o escoamento do ?leo atrav?s do duto, reduzindo as perdas de carga por atrito. Para verificar estas intera??es estudou-se a molhabilidade das superf?cies, que ? representada pela medida do ?ngulo de contato de solu??es de tensoativo com placas planas de a?o inoxid?vel 304. Foram utilizadas solu??es de KCl, tensoativos e misturas de tensoativos com cadeia carb?nica linear e arom?tica de grupos etoxilados variando de 3 a 100. Para determina??o da molhabilidade foi utilizado o goni?metro DSA 100, Kr?ss. A fim de observar a influ?ncia da rugosidade na molhabilidade, a placa de a?o inoxid?vel foi usinada e polida com diferentes lixas de refer?ncia de 100 at? 1200. Os resultados obtidos mostraram que lixar e polir a placa resulta em diminui??o da molhabilidade. Quanto ?s solu??es de tensoativos, estas apresentaram melhor molhabilidade em a?o inoxid?vel do que as solu??es de KCl testadas. Tamb?m foi observado que a mistura de tensoativos ? uma op??o consider?vel, uma vez que apresentou ?ngulos de contato satisfat?rios para uma boa molhabilidade na placa de a?o inoxid?vel. Outro fato observado ? que a etoxila??o tamb?m interfere na molhabilidade, reduzindo o ?ngulo de contato com a redu??o da etoxila??o. Isto nos leva a concluir que tensoativos com maior etoxila??o, sendo mais hidrof?bicas, diminuem a intera??o da ?gua com o duto e, consequentemente, o atrito com o mesmo, melhorando assim o escoamento
41
Blakelock, Eleanor Susan. "The early medieval cutting edge of technology : an archaeometallurgical, technological and social study of the manufacture and use of Anglo-Saxon and Viking iron knives, and their contribution to the early medieval iron economy." Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/5517.
Full textAbstract:
A review of archaeometallurgical studies carried out in the 1980s and 1990s of early medieval (c. AD410-1100) iron knives revealed several patterns, with clear differences in knife manufacturing techniques present in rural cemeteries and later urban settlements. The main aim of this research is to investigate these patterns and to gain an overall understanding of the early medieval iron industry. This study has increased the number of knives analysed from a wide spectrum of sites across England, Scotland and Ireland. Knives were selected for analysis based on X-radiographs and contextual details. Sections were removed for more detailed archaeometallurgical analysis. The analysis revealed a clear change through time, with a standardisation in manufacturing techniques in the 7th century and differences between the quality of urban and rural knives. Analysis of cemetery knives revealed that there was some correlation between the knife and the deceased. Comparison of knives from England, Dublin and Europe revealed that the Vikings had little direct impact on England's knife manufacturing industry, although there was a change in manufacturing methods in the 10th century towards the mass produced sandwich welded knife. This study also suggests that Irish blacksmiths in Dublin continued their 'native' blacksmithing techniques after the Vikings arrived. Using the data gathered a chaîne opértoire of the iron knife was re-constructed, this revealed that there was a specific order to the manufacture process and decisions were not only influenced by the cost of raw materials, the skill of the blacksmith and the consumer status, but also by cultural stimulus.
42
Le, Nué Charline. "Étude de la relation microstructure/ténacité d'aciers maraging inoxydables." Thesis, Ecole nationale des Mines d'Albi-Carmaux, 2017. http://www.theses.fr/2017EMAC0003.
Full textAbstract:
L'acier maraging inoxydable MLX17, développé et élaboré par Aubert & Duval, est une nuance candidate pour des applications dans le domaine de l’aéronautique. Cette nuance possède un fort potentiel en termes de résistance mécanique qui dépasse celle des autres nuances inoxydables. Cependant, elle s’avère sensible à la vitesse de refroidissement après revenu, qui influence directement la ténacité. La recherche des origines scientifiques de la dégradation de la ténacité lorsque la vitesse de refroidissement après revenu diminue (refroidissement à l'air par rapport à un refroidissement à l'eau) constitue l’objectif majeur de cette thèse. Un suivi des modifications microstructurales de la nuance, selon différentes conditions de revenu a été réalisé. Une démarche intégrant différentes échelles d'observation (de l’échelle macroscopique jusqu'à l'échelle atomique) s’est imposée au vu de la complexité de la microstructure. Parallèlement, l’étude des propriétés mécaniques en traction et en résistance à la propagation brutale de fissure a été menée afin de s’attacher en permanence à corréler le comportement mécanique à l’évolution microstructurale observée pour les différentes conditions de revenu. Les analyses par dilatométrie et par sonde atomique tomographique ont permis de mettre en évidence la formation d’un complément de précipitation, à l'origine de la dégradation de la ténacité. Pour permettre une meilleure maîtrise du complément de précipitation et le rendre moins fragilisant, une modification des conditions de revenu a été proposée. Cette alternative a permis d'obtenir une amélioration du compromis résistance/ténacitéThe stainless maraging steel MLX17, produced and developed by Aubert & Duval, is a candidate for applications in the field of the aeronautics. This steel possesses a high potential in term of mechanical resistance that exceeds that of the other stainless steels. However, the fracture toughness of this grade proves to be sensitive to the cooling rate after aging, resulting of a dispersal of this property. The research of the scientific origins of the degradation of the fracture toughness by a decrease of the cooling rate (air cooling in comparison to water cooling) is the main objective of this thesis. The microstructure was observed for several aging conditions. An approach using various scales (from micrometric to atomic scale) was necessary because of the complexity of the microstructure. In parallel, the study of tensile mechanical properties and resistance to propagation of cracks was led. The aim was to correlate the mechanical behavior to the microstructural evolution observed for the aging conditions investigated. Microstructural analyses by dilatometry and atomic tomography probe have shown the formation of a complementary precipitation of the hardening phase, responsible of the fracture toughness deterioration. In order to have a better control of this additional precipitation and to make it less fragile, a modification of the aging conditions was proposed. This alternative enabled an improvement of the trade-offs between the high strength and the fracture toughness
43
Júnior, Enio Carlos Mesacasa. "Comportamento estrutural e dimensionamento de cantoneiras de aço formadas a frio submetidas à compressão." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-17052012-093741/.
Full textAbstract:
Envolto ao já conhecido comportamento de cantoneiras esbeltas de abas iguais, questões aparentemente contraditórias tem sido reportadas em estudos experimentais de diversos autores, entre elas a ocorrência de modos de instabilidade em desacordo com aqueles obtidos via análise de estabilidade elástica, e forças axiais resistentes muito diferentes dos resultados teóricos (em geral, conservadoramente). Nestas condições, este trabalho procura analisar a fundo o comportamento das cantoneiras esbeltas de abas iguais, de modo a contribuir com o entendimento dos fenômenos que dificultam a interpretação dos resultados experimentais, dentre os quais, o afastamento longitudinal entre a rótula e a extremidade das barras (no caso de barras com extremidades rotuladas), e o sentido da imperfeição global de flexão em torno do eixo de menor inércia, o qual mostrou-se um fator chave na determinação do comportamento das cantoneiras, especialmente para comprimentos próximos da transição entre os dois modos globais de instabilidade elástica. Para esta faixa de comprimentos, diferentes níveis de interação entre os dois modos globais podem ser obtidos. Ademais, estudos experimentais realizados por diversos autores, aqui complementados por uma série de ensaios realizados em cantoneiras com extremidades engastadas, formam um vasto banco de resultados, que é utilizado para (além de comparações nos estudos teóricos) avaliar diversos procedimentos de previsão teórica sugeridos por diferentes autores, ou advindos de interpretações a partir do procedimento normativo, à luz do comportamento teórico estudado na primeira etapa do trabalho. Assim, destes procedimentos, apenas um baseado no Método da Resistência Direta, e dois baseados no Método das Larguras Efetivas demonstraram bons resultados, sendo que todos eles, desconsiderando o modo de flexo-torção como um modo global de instabilidade. Ao fim, comenta-se da necessidade de se expandir alguns estudos específicos, pois ao adotar-se um procedimento baseado somente no modo global de flexão, apesar de se mostrar estatisticamente mais eficiente, verifica-se a possível ocorrência de resultados demasiadamente contra a segurança.On the well known behavior of equal-leg angle columns, some questions apparently paradoxical have been reported in experimental results from several authors, including the occurrence of different instability modes from the expected by the elastic stability analysis, and maximum axial compressive load expressly different (generally conservative) from theoretical previsions. Therefore, the aim of this work is to improve the knowledge about the equal-leg angle columns behavior, contributing to the understanding of the features that complicate the interpretation of experimental results, among which, the longitudinal distance between the end sections and the center of hinges (pin-ended columns), and also the direction of the minor-axis flexural initial imperfection, which proved to play a key role in the post-critical column behavior, specially for column lengths near of the transition between global buckling modes (major-axis flexural-torsional and minor-axis flexural modes). On this range of lengths, different modal interaction amplitudes can be obtained, only with the direction of the minor-axis flexural initial imperfection (i.e., the amplitude of this imperfection plays a negligible influence on the column behavior). Furthermore, putting together a fairly large column ultimate strength data bank comprising experimental test results performed by several authors, collected from the available literature, and new experimental results on fixed-ended angle columns performed in this work, important comparisons with theoretical studies can be showed as well as evaluation of several ultimate strength theoretical prevision procedures, either those suggested by another authors as those arising from interpretations of normative procedures in the light of theoretical behavior verified in the first stage of labor. In conclusion, only one procedure based on Direct Strength Method and two procedures based on Effective Width Method exhibited accurate results, all of which neglecting the flexural-torsional mode as a global mode. Thus, it is important to mention that some additional studies are needed, because if adopted a procedure based only in the minor-axis flexural mode, despite being statistically advantageous, it is verified the possibility to occurs quite unconservative results.
44
Dellong, David. "Failles actives et structures profondes de la Marge Est-Sicilienne." Thesis, Brest, 2018. http://www.theses.fr/2018BRES0065/document.
Full textAbstract:
Le bassin Ionien, en Méditerranée centrale, abrite une zone de subduction à vergence Nord-Ouest où la plaque Afrique plonge sous les blocs Calabro-Péloritain au Nord-Est de la Sicile. Cette subduction résulte de la lente convergence entre les plaques tectoniques Afrique et Eurasiatique. Bien que de nombreuses campagnes d’exploration scientifique ont été menées dans cette zone particulière, plusieurs questions géodynamiques restent débattues. Tout d’abord la croûte pavant le bassin Ionien pourrait être soit de nature continentale amincie et représenter une extension de la plaque Afrique, soit océanique (Néo-Téthys) faisant de ce bassin l’un des plus anciens domaines océaniques au monde. L’escarpement de Malte représente un vestige de l’ouverture du bassin, mais les mécanismes de rifting et notamment la géométrie d’ouverture du bassin restent débattus. Cette subduction est en retrait vers le Sud-Est depuis les derniers 35 Ma, mais est aujourd’hui confinée à l’étroit bassin Ionien. Afin d’accommoder ce retrait de la plaque plongeante dans le bassin, une grande faille de déchirure lithosphérique de bord de subduction (STEP fault en anglais pour « subduction Transform Edge Propagator ») doit se propager le long de la marge Est-Sicilienne. Cependant, sa position en surface reste difficile à déterminer dans l’épais prisme d’accrétion recouvrant le bassin. Ces questions ont été explorées par modélisation des données de sismique grand angle de la campagne DIONYSUS (Octobre 2014, R/V Meteor) le long de deux profils perpendiculaires à la marge Est-Sicilienne. Des modélisations gravimétriques en 3D ont aussi été réalisées dans le but de localiser la plaque plongeante en profondeur sous les blocs Calabro-Péloritains. La sismicité des trois structures majeures du bassin : l’escarpement de Malte, l’AFS (Alfeo Fault System), et l’IFS (Ionian Fault System) a permis d’étudier leurs activités à l’actuel. Les résultats obtenus permettent d’observer une croûte océanique au fond du bassin. La structure profonde de l’escarpement de Malte est observée comme une zone d’amincissement crustal abrupt, ce qui est caractéristique des marges transformantes. Un profond bassin sédimentaire asymétrique (11 km) est observé au Sud du détroit de Messine. Il s’est probablement ouvert récemment entre les blocs continentaux Péloritain et Calabre. Dans le lobe Ouest du prisme d’accrétion Calabrais, le modèle de vitesse permet d’observer l’indentation du prisme clastique interne dans le prisme évaporitique externe. Des modélisations analogiques utilisant sable et silicone ont permis de démontrer la récente activité de ce lobe. L’interprétation des modèles de vitesse permet de localiser la faille STEP le long de l’AFS sur les deux profilsIn the Ionian Sea (central Mediterranean) the slow convergence between Africa and Eurasia results in the formation of a narrow subduction zone. The nature of the crust of the subducting plate remains debated and could represent the last remnants of the Neo-Tethys ocean. The origin of the Ionian basin is also under discussion, especially concerning the rifting mechanisms as the Malta Escarpment could represent a remnant of this opening. This subduction retreats toward the south-east (motion occurring since the last 35 Ma) but is confined to the narrow Ionian basin. A major lateral slab tear fault is required to accommodate the slab rollback.This fault is thought to propagate along the eastern Sicily margin but its precise location remains controversial.This PhD project focussed on the deep sedimentary and crustal structures of the eastern Sicily margin and the Malta Escarpment (ME). Two two-dimensional P wave velocity models were modelled by forward Modelling of wide-angle seismic data, acquired onboard the R/V Meteor during the DIONYSUS cruise in 2014.A 3D gravity model of the region was also performed to constrain the depth of the subducting slab bellow the Calabro-Peloritan backstops. The seismicity of the three structures identified in the velocity models (ME, Alfeo fault System, Ionian Fault System) permits to study their recent activity. The results image an oceanic crust within the Ionian basin as well as the deep structure of the Malta Escarpment, which presents characteristics of a transform margin. A deep and asymmetrical sedimentary basin is imaged south of the Messina strait and seems to have opened between the Calabrian and Peloritan continental terranes. In the western lobe of the Calabrian accretionary prism, the southern velocity model allows to observe the indentation of the internal clastic wedge into the external evaporitic wedge, thus showing the recent activity of this lobe. The interpretation of the velocity models suggests that the major STEP fault is located east of the Malta Escarpment, along the Alfeo Fault System
45
Kholmatov, Shavkat. "On some positive effects of swirling flow for the continuous cast mould billets." Licentiate thesis, Stockholm : Division of Applied Process Metallurgy, School of Industrial Engineering and Management, Royal Institute of Technology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4453.
Full text
46
Babic, Marijan. "Role of Interfacial Chemistry on Wettability and Carbon Dioxide Corrosion of Mild Steels." Ohio University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1483543296145156.
Full text
47
Lepourry, Clémence. "Mise au point et caractérisation d’un système innovant de poutre hybride béton-acier : étude des comportements locaux et globaux." Thesis, Rennes, INSA, 2019. http://www.theses.fr/2019ISAR0016.
Full textAbstract:
L’objectif principal de cette thèse de doctorat est le développement et la caractérisation d’un procédé de poutres de grandes portées adapté aux entreprises de gros œuvre. En effet, les technologies industrielles existantes pour répondre à des franchissements importants ne sont pas en accords avec le savoir-faire des équipes chantiers. Dès lors, le groupe Legendre, par sa filiale Ingénova, a souhaité mettre au point une solution, simple de par sa mise en œuvre sur chantier, et qui vise un niveau d’exigence structurelle similaire aux technologies actuelles. Composée d’une poutre béton armé renforcée par une peau métallique extérieure, la poutre hybride béton-acier est la solution étudiée au sein de ce mémoire pour répondre à cette problématique. Pour assurer l’équilibre des efforts entre les deux matériaux, un système de connexion inédit a été développé. La caractérisation expérimentale n’ayant validé que deux dimensions de connecteurs, le modèle numérique a permis d’étendre l’étude et ainsi, déterminer une formule de dimensionnement généralisée. Le comportement local de la poutre connu, les investigations expérimentales se sont orientées sur la réponse de la poutre soumise à une flexion positive. L’impact de la connexion partielle en comparaison de la connexion complète a été quantifié à la fois sur la résistance de la poutre et sur ses déformations. Le modèle numérique, calibré sur les résultats des essais, a permis de valider l’utilisation de modèles analytiques issus de la littérature, adaptés au cas de la poutre hybride. Enfin le dernier volet de cette thèse concerne l’assemblage de la poutre hybride béton-acier avec un poteau mixte acier-béton tubulaire. Après une série d’essais pour caractériser la résistance et la rigidité de ce joint innovant, un modèle numérique de cette configuration a mis en évidence les transferts d’efforts nécessaires entre les deux matériaux. Ces derniers complètent le mode de fonctionnement classique de l’assemblage qui superpose à la fois un comportement béton armé et un comportement métallique. Un modèle analytique, développée au sein de cette thèse, a confirmé le dimensionnement de l’assemblage.Les résultats présentés dans ce mémoire ont été suffisants pour tester le procédé de poutre hybride béton-acier sur un chantier pilote. Le gain de la solution en comparaison aux technologies existantes a été confirmé par les équipes chantiersThe main goal of this Ph.D thesis is the development and the characterization of a solution for long-span beams in concrete buildings. Pre-stressed or composite beams are the possible technologies for beams up to twenty metres, but they are not adapted for concrete constructors. The main objective of Ingenova, the research and development affiliate of Legendre is to find a solution, which can be set up easily by concrete workers with good structural performance. The proposed solution is the concrete-steel hybrid beam, made of U-shape steel profile used as permanent formwork to encase a concrete beam. The association of the two beams also gives a convenient solution adapted to concrete builders. In this thesis, a series of experimental and numerical tests have been performed in order to assess the global and the local behaviour of the beam and its connections.Firstly, the connexion between concrete and steel is achieved by L-shaped angles welded on the upper flanges of the steel beam. Their behaviour has been studied by performing asymmetric push-out tests, which were used to validate a detailed finite element model. Based on the results obtained from a numerical parametric study of the validated a finite element model, an analytical expression of the shear resistance was then proposed.The global behaviour in sagging of the concrete-steel hybrid beam was also investigated by experimental and numerical tests. The impact of the partial interaction under deflection and bending moment resistance have been studied. The results show a ductile behaviour of the concrete-steel hybrid beam both in partial and in full interaction. Finally, an analytical method has been adapted to determine the ultimate flexural capacity of this innovative beam considering the degree of connection. The last part of this work concerns the joint between the concrete-steel hybrid beam and a concrete-filled steel tubular column. The behaviour of this hybrid joint was verified by full-scale experimental tests. A finite element model has also been developed in order to investigate more deeply into the load transferring mechanism within the joint. This FE model is validated by comparing its results against experimental data. An analytical model for the design of the joint is then proposed.This new technology has already been used in actual projects during the thesis. The design procedure of the members and of the joints has been approved by the CSTB, the French certification organism of construction. First feedback for the on-site erection were good, and workers enjoyed the quick assembly and the increase of security on site
48
Branquinho, Maria Ávila. "Sobre o comportamento estrutural e o dimensionamento de cantoneiras de aço formadas a frio submetidas à compressão e conectadas por uma aba." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-30032017-103451/.
Full textAbstract:
A cantoneira de abas iguais é encontrada laminada ou formada a frio. Quando laminada, normalmente possui abas compactas, isto é, se submetida à compressão, não apresenta instabilidade local e, para a faixa usual de comprimentos, não apresenta também o modo global de flexo-torção como dominante. Quando formada a frio, estes modos predominam, uma vez que a relação largura-espessura torna-se elevada. A elevada esbeltez das abas, juntamente com as peculiaridades do seu comportamento mecânico, pode conduzir a significativas divergências entre a força axial resistente (experimental) quando comparada aos valores oriundos dos procedimentos de cálculo apresentados pelas normas. As divergências são ainda maiores quando se considera a cantoneira em sua situação mais usual: sob compressão excêntrica devido à ligação parafusada ou soldada em uma das abas. No presente trabalho foi analisado o comportamento mecânico das cantoneiras formadas a frio e conectadas pela aba por dois parafusos e desenvolvida uma formulação baseada no método do comprimento de flambagem equivalente, bem como identificados seus modos de instabilidade e a respectiva participação modal para diversas faixas de esbeltez. Para validar esta formulação, foi realizada uma análise de confiabilidade que resultou em índices de confiabilidade (β) de acordo com as exigências normativas.The equal-leg angle is found hot-rolled or cold-formed. When hot-rolled, it usually has compact legs, that is, if subjected to compression it does not present local buckling and it does not present a global flexo-torsion buckling mode as dominant for the usual range of lengths. When cold-formed, these modes predominate, since the width-to-thickness ratio becomes high. The high slenderness of the legs, together with the peculiarities of its mechanical behavior, can lead to significant divergences between the axial strength (experimental) and the values from standard\'s procedures. The divergences are even greater when considering the angle in its most usual loading situation: under eccentric compression due to bolted or welded connection in one leg. In the present work the mechanical behavior of the cold-formed angles connected by the leg by two bolts was analyzed in order to propose a formulation based on the equivalent buckling length method, as well as, to define its buckling modes and the respective modal participation for different slenderness ranges. To validate this formulation, a reliability analysis was performed that resulted in reliability indexes (β) according to the design standards requirements.
49
Stloukal, Štěpán. "Zesílení ŽB sloupu pomocí ocelové bandáže." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265384.
Full textAbstract:
The steel bandage is an economical and effective widely used method for strengthening RC columns. Diploma thesis reviews most common design proposals for the types of the bandage with directly loaded and not directly loaded steel angles. This work also includes a comparison of the different constitutive laws for confined concrete. In order to simulate real behaviour of strengthened structure the numerical analysis has been carried out using non-linear software ATENA. According to the European standards and adopted hypotheses the simplified analytical model has been derived to be able to calculate load-bearing capacity of a strengthened column under normal force and bending moment. The proposed model considers the contribution in confinement pressure caused by steel bandage and the contribution of directly loaded angles. In addition, the direct application on real frame structure has been performed.
50
Tristão, Gustavo Alves. "Análise teórica e experimental de ligações viga mista-pilar de extremidade com cantoneiras de assento e alma." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-28092006-101125/.
Full textAbstract:
Este trabalho apresenta um estudo numérico e experimental do comportamento estrutural das ligações viga mista-pilar com cantoneiras de assento e alma. No estudo teórico foi desenvolvido, com base nos EUROCODES 3 e 4, um procedimento para avaliação do comportamento das ligações mistas com cantoneiras de alma e assento e com chapa de topo. O trabalho de investigação experimental, abrangendo modelos submetidos a carregamentos monotônico e cíclico, foi realizado no Instituto Superior Técnico (IST), Portugal, em que o objetivo principal foi avaliar a influência da força axial de compressão no pilar para o comportamento do painel da alma do pilar, e conseqüentemente no comportamento global da ligação mista localizada em nó de extremidade. Nos ensaios experimentais foram analisadas as rotações e deformações no painel da alma do pilar sem e com enrijecedor na alma do pilar. Adicionalmente, a eficiência da ancoragem das barras de armadura longitudinal foi verificada. Paralelamente à investigação experimental, um estudo numérico de ligações mistas foi realizado por meio do modelo em elementos finitos, o qual mostrou-se representativo, tornando-se uma ferramenta para análises paramétricas.This work presents a numerical and experimental study of the structural behavior of beam-to-column composite joints with bottom and web angle connections. In the theoretical study, basing in EUROCODES 3 and 4, an analytic procedure for evaluation the static behavior of beam-to-column composite joints with bottom and web angle connections was developed. The experimental test program, enclosing monotonic tests and a cyclic test, was carried out at the Instituto Superior Técnico of Lisbon (IST), where the main objective was to evaluate the effect of column axial load on column web panel and consequently in the global behavior of single-sided composite joint. In the tests, the panel zone rotations and deformations were analyzed for stiffened and unstiffened column web. In addition, the efficiency of the main rebar was verified. Finally, a thorough of finite element model, a numerical study of composite joints was developed. This model was found to be representative and reliable as a tool to futures parametric analyses.