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The Effect of Global Temperature Increase on Lake-Effect Snowfall Downwind of Lake ErieFerian, Michael R. January 2008 (has links)
No description available.
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Temperature Increase Effects on Sagebrush Ecosystem Forbs: Exprimental Evidence and Range Manager PerspectivesWhitcomb, Hilary Louise 01 May 2011 (has links)
Sagebrush plant communities are among the most threatened in North America. This project had two goals: to test how increased temperature affects native and nonnative forb species common to the Western sagebrush region and to evaluate land manager beliefs about changes in their ecosystems, including those affecting forb species.
Native forbs Sphaeralcea munroana, Crepis acuminata, Linum lewisii, Penstemon palmeri, and Oenothera pallida and non-natives Erodium cicutarium and Lactuca serriola were each subjected to two treatments: experimental warming using open-top chambers and a control. Knowing how forbs used in restoration might respond to future conditions is both practical and economical information for land managers. Responses to an open-top chamber treatment suggest that S. munroana, L. lewisii, and P. palmeri may be resilient to predicted increases in temperature, while C. acuminata and O. pallida should be used with caution. As expected, temperature did not affect E. cicutarium fitness but did lead to earlier germination. This result supports the concept that competitive interactions between non-natives and natives could be compounded by increased temperature. Transplanted L. serriola was negatively affected by warming.
Semi-structured phone interviews of range managers in Utah, Idaho, Nevada, Wyoming, Oregon, and Montana addressed demographics, local climate and land changes, and forb knowledge. Additionally, local long-term climate data sets were compared to responses. Most states respondents were evenly split about beliefs of climate change in their area (half said there were no changes, and have said they thought there were some changes). Montana was the exception; Montana’s recent increases in climate-related events may explain most of the managers noting changes. Managers that had more years at their job gave more qualified, but also more accurate climate answers. Managers saying there was no change tended to base their answers on recent weather conditions, while managers that said they did notice changes tended to base their answers on long-term patterns. Forbs typically were not viewed as an important indicator of ecosystem health or resilience. This study indicates restoration organizations might benefit from more specified outreach to managers which focuses on local climate, forbs (especially those known to be used by Greater sage-grouse), and solutions.
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Influence of heat on the physical and mechanical properties of selected rock typesSaiang, Christine January 2011 (has links)
Impelled by the increase in the number of tunnel fires in the last decade alone, wide spread attention has been drawn towards tunnel fire safety studies. Many of these fires occurred in road and railway tunnels involving vehicles and trains. These fire incidents have claimed lives, caused structural damages to the tunnel infrastructure and even economic losses to the government, businesses and communities concerned. When there is a fire in a tunnel, the temperature inside the tunnel increases rapidly to magnitudes as high as 1500°C. At such high temperatures costly damages to the tunnel structure is inevitable. Having an understanding of the detrimental effects of such high temperatures is essential and valuable when carrying out preliminary assessment of the type and extent of damage in the tunnel. This would in turn provide useful information in determining the appropriate remedial measures required to make the tunnel safe and usable again in the aftermath of a tunnel fire. In most tunnel fire safety studies, the focus has been on the behaviour of concrete, since of course concrete is one of the major support elements in tunnels. However, in several cases, such as in Scandinavia for example, where the rock mass is competent enough to support itself only a thin layer of shotcrete is used usually on tunnel walls. In such cases the rock will be fully exposed to heat in an instance of fire. In this case, whether it is prevention or maintenance of the tunnel, it would require knowledge on the effect of elevated heat on the rock mass. Hence, it is line with this thinking that a study was initiated by the Swedish Transport Administration (Trafikverket), Kärnbränslehantering AB, SKB and Vattenfall to study the effect of heat on the physical and mechanical properties of some common rock types, and hence the focus of this thesis. This thesis presents the results of a series of laboratory studies which was carried out to investigate the effect of heat on the physical and mechanical properties of selected rock types, namely; diabase, granite and quartzitic schist. Samples from these rock types were heat treated at temperature levels of 400°C, 750°C and 1100°C, before investigating their mechanical and physical properties through mechanical testing and microscopic investigations of thin sections. Because the effect of heat on rock can be affected by the heating rate and exposure time, the test were conducted under controlled conditions in order to avoid significant variation in the results. The results clearly show that the rock types behave differently at different temperature levels, which tend to depend on the mineral composition and micro cracks distribution. As the temperature increases the rock forming minerals undergo changes in their chemical structure thus causing them to alter from the original phase they had existed in. With these phase changes different reactions take place such as re-crystallization, the loss of crystal bound water, thermal expansion and micro cracking of mineral grains as well as the development of voids. These microscopic changes were manifested in the macro-scale by the variations observed in the behaviour of strength and stiffness of the samples in the mechanical tests.
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Utvärdering av en billig ultraljudsmaskin med avseende på bildkvalitet och temperaturökning / Evaluation of a Cheap Ultrasound Machine with Respect to Image Quality and Temperature IncreaseDragunova, Yulia, Anderberg, Joakim January 2021 (has links)
Ultraljudsdiagnostik baseras på propagering av mekaniska vågor och används för att avbilda tvärsnitt av kroppen i realtid. Prestandan, med avseende på kontrast, upplösning och måttmätningar, av CONTEC CMS600B-3, en relativ billig maskin är av intresse. Hur volymen av en fantom, dess ytarea och frekvens på utskickade vågor påverkar uppvärmningen av vävnader är även av intresse. Det undersöktes med ultraljudsmaskinerna CONTEC CMS600B-3 och Philips Lumify för att få resultat som inte beror på endast en maskin. Axiella upplösningen på CONTEC CMS600B-3 uppmättes med hjälp av ett gem till 0,61 mm och den laterala upplösningen till 1,27 mm med hjälp av ett snitt i cement. Maskinens måttmätningar hade en relativ avvikelse beroende på mätning. Resultat för reflektionskoefficienten visade att ultraljudsmaskinen har en funktion som kompenserar för attenuering och förstärker signaler med låga amplituder. Temperaturmätningarna undersöktes genom att skapa fantomer som efterliknar mänskliga vävnader med olika volymer och ytareor. En undersökning med ultraljudsmaskinerna visade att mer temperaturökning sker då ytarean ökas när volymen hålls konstant. Med avseende på säkerhet i temperaturökning, axiell upplösning och area/omkrets mått uppfyller CONTEC CMS600B-3 inte standarden och kan därmed inte användas inom sjukvården. / Diagnostics with ultrasound are based on propagation of mechanical waves and is used for imaging cross-section of the body in real-time. Performance, regarding contrast, resolution, and size measure, of CONTEC CMS600B-3, a relatively cheap machine is of interest. How volume of a phantom, its surface area, and frequency of the waves affects the heating of the tissues is also of interest. It was measured using ultrasound machines CONTEC CMS600B-3 and Philips Lumify to obtain results independent of the machine used. The axial resolution of CONTEC CMS600B-3 was established with a paperclip to be 0.61 mm and the lateral resolution was measured to be 1.27 mm using concrete with a triangular slit. Measurements of the machine had a relative deviation was depending on the measure. Results of the reflection coefficient indicated that CONTEC CMS600B-3 has a built-in function that compensates for loss of intensity due to attenuation and amplifies signals with lower amplitude to produce a B-mode image that the user can understand. Temperature measurements were done on phantoms that mimic the human body with different volumes and surface areas. An investigation with ultrasound machines showed an increase in temperature with increased surface area as the volume is held constant. When looking at safety with temperature rise, axial resolution and area/circumference measurements, CONTEC CMS600B-3 does not meet the standard and therefore cannot be used in healthcare.
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Měření výkonu v ultrazvukových polích / Power measurement in ultrasound fieldsŠkůrek, Pavel January 2010 (has links)
This work is focused on the developement of a sensor, which enables to measure the ultrasonic power by heat effect of the mechanical Wales. The princip of two basic kinds of thermoacoustic sensor is descibed here – one level and two level sensor. This work also contains a proposition of these sensors with description of each parts and a trial to find suitable absorber. Achieved results, which support the function of the sensors are presented here by form of graphs and tables. Measuring by thermoacoustic sensors is confronted here with measuring of ultrasonic by hydrophone, which is used as reference measuring.
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Berücksichtigung von Temperaturfeldern bei Ermüdungsversuchen an UHPCDeutscher, Melchior 07 March 2023 (has links)
Die Anforderungen an Baumaterialien steigen durch immer schlankere und höhere Tragwerke. Im Massivbau geht daher seit längerem die Materialentwicklung hin zu hochfesten und ultrahochfesten Betonen. Neben der steigenden statischen Beanspruchung nimmt gleichzeitig, bedingt durch immer ausgereiztere Konstruktionen, die Bedeutung der Ermüdungsfestigkeit zu. Deswegen liegt der Fokus der Forschung im Bereich der Hochleistungsbetone aktuell vor allem auf der Widerstandsfähigkeit gegenüber zyklischen Beanspruchungen. Dabei wurde in verschiedenen Forschungsvorhaben bei höheren Prüfgeschwindigkeiten bei Druckschwellversuchen zur Erzeugung von Wöhlerlinien eine Erwärmung der Probekörper festgestellt. Diese Arbeit widmet sich dieser Thematik bezogen auf ultrahochfesten Beton.
Mit einer umfangreichen Parameterstudie konnte ein Überblick über maßgebende Einflussgrößen auf den Erwärmungsprozess gegeben werden. Als wichtigste Ursachen für die Temperaturerzeugung wurde zum einen ein inneres Reibungspotenzial festgestellt, welches mit geringer werdendem Größtkorn und durch wachsende Schädigung ansteigt. Zum anderen ist die eingetragene Energie pro Lastwechsel entscheidend. Anders als die Ermüdungsfestigkeit von Beton, die vor allem von der Oberspannung abhängig ist, ist die Erwärmung pro Lastwechsel von der Spannungsamplitude abhängig. Die Prüfgeschwindigkeit beeinflusst die messbare Erwärmung hingegen nur durch die Veränderung des Zeitraums, der pro Lastwechsel zur Temperaturabgabe zur Verfügung steht. Die Temperaturgenerierung pro Lastwechsel ist hingegen frequenzunabhängig.
Ein negativer Einfluss der Probekörpererwärmung zeigt sich vor allem bei der deutlichen Reduzierung der Bruchlastwechselzahlen im Vergleich zu Versuchen, bei denen kein deutlicher Temperaturanstieg zu verzeichnen war. Basierend auf bisherigen Arbeiten zu hochfesten Betonen schlagen deswegen verschiedene Autoren eine Anpassung des Versuchsablaufs zur Begrenzung der Temperaturentwicklung im Probekörper vor. Die vorliegende Arbeit zeigt im Gegensatz dazu eine Methode auf, bei der die Erwärmung zugunsten einer zeiteffizienten Prüfung zugelassen und anschließend bei der Auswertung berücksichtigt wird. Als eine Hauptursache für das vorzeitige Versagen bei starker Erwärmung wurde die statische Druckfestigkeit, welche temperaturabhängig
ist, ausgemacht. Steigt die Temperatur, reduziert sich gleichzeitig die Druckfestigkeit. Dies führt bei kraftgesteuerten Druckschwellversuchen mit konstantem Lastspiel zu einer Veränderung des bezogenen Spannungsspiels. Vor allem die stark steigende bezogene Oberspannung führt schlussendlich zu einem vorzeitigen Ermüdungsversagen. Da die Temperatur bei den Versuchen, die vor den rechnerischen Erwartungswerten versagen, stetig bis zum Versagenszeitpunkt ansteigt, ist der Probekörper einer sich über die Versuchsdauer veränderlichen bezogenen Beanspruchung ausgesetzt. Bei der Versuchsauswertung kann ein veränderliches Lastspiel nicht für die Einordnung in Wöhlerdiagramme verwendet werden. Weil die Verwendung der Lasteingangsgrößen zu einer Unterschätzung der Ermüdungsfestigkeit führt, muss eine Ermittlung eines äquivalenten konstanten
Spannungsspiels erfolgen, welches die Festigkeitsveränderung des Betons berücksichtigt. Anhand der durchgeführten Druckschwellversuche und der temperaturabhängigen Druckfestigkeit wurde eine analytische Methode entwickelt, mit der unter Verwendung der anfänglichen Lastamplitude sowie der gemessenen maximalen Temperatur eine angepasste Oberspannung berechnet und dann die erreichte Bruchlastwechselzahl in ein Wöhlerdiagramm eingetragen werden kann.
Diese Methode wird für den vertieft untersuchten ultrahochfesten Beton für eine Vielzahl von Lastkonfigurationen sowie zusätzlich für Versuchsergebnisse eines hochfesten Betons abschließend verifiziert.:Inhaltsverzeichnis
1 Einleitung und Aufbau 1
1.1 Einleitung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.3 Aufbau der Arbeit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2 Stand des Wissens 5
2.1 Grundlagen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1.1 Ermüdungsbeanspruchung . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1.2 Betonermüdung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1.3 Ultrahochfester Beton (UHPC) . . . . . . . . . . . . . . . . . . . . . . . . 12
2.1.4 UHPC unter Ermüdungsbeanspruchung . . . . . . . . . . . . . . . . . . . 14
2.2 Einfluss der Temperatur auf die statische Druckfestigkeit . . . . . . . . . . . . . . 15
2.2.1 Wissenschaftliche Untersuchungen . . . . . . . . . . . . . . . . . . . . . . 15
2.2.2 Regelung nach fib Model Code 2010 (2012) . . . . . . . . . . . . . . . . . 17
2.3 Betonerwärmung bei zyklischen Versuchen – Wissensstand bis 2017 . . . . . . . . 18
2.3.1 Einflussparameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.3.2 Temperaturentwicklung im Probekörper . . . . . . . . . . . . . . . . . . . 23
2.4 Zielstellung der Arbeit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.5 Betonerwärmung bei zyklischen Versuchen - Wissensstand ab 2017 . . . . . . . . 24
2.5.1 Elsmeier - Parameterstudie zur Erwärmung von hochfesten Vergussbetonen 24
2.5.2 Bode - Energetische Auswertung von Ermüdungsversuchen . . . . . . . . . 28
2.5.3 Schneider - Frequenzeinfluss auf den Ermüdungswiderstand von hochfestem
Beton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.5.4 Markert - Feuchte- und Wärmeeinfluss auf die Ermüdungsschädigung von
HPC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
2.6 Zusammenfassung und Abgrenzung . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3 Eigene Forschung 37
3.1 Grundlagen zur Versuchsdurchführung . . . . . . . . . . . . . . . . . . . . . . . . 37
3.1.1 Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
3.1.2 Herstellung, Lagerungsbedingungen und Probekörpervorbereitung . . . . . 39
3.1.3 Probengeometrie und Messapplikationen . . . . . . . . . . . . . . . . . . . 39
3.1.4 Versuchsdurchführung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3.1.5 Betonchargen und Versuchsmatrix . . . . . . . . . . . . . . . . . . . . . . 42
3.2 Auswertung von Temperaturmesswerten . . . . . . . . . . . . . . . . . . . . . . . 44
3.3 Temperaturentwicklung und -verteilung im Probekörper . . . . . . . . . . . . . . 46
3.4 Parameterstudie . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
3.4.1 “Experimental Investigations on the Temperature Increase of Ultra-High
Performance Concrete under Fatigue Loading“ Deutscher et al. (2019) . . 49
3.4.2 “Experimental Investigations on Temperature Generation and Release
of Ultra-High Performance Concrete during Fatigue Tests“ Deutscher
et al. (2020a) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
3.4.3 “Heating rate with regard to temperature release of UHPC under cyclic
compressive loading“ Deutscher et al. (2021a) . . . . . . . . . . . . . . . . 86
3.4.4 “Influence of the compressive strength of concrete on the temperature
increase due cyclic loading“ Deutscher et al. (2020b) . . . . . . . . . . . . 98
3.4.5 Ergänzungen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
3.4.6 Zusammenfassung der Parameterstudie . . . . . . . . . . . . . . . . . . . . 116
3.5 Vergleich mit dem Stand des Wissens . . . . . . . . . . . . . . . . . . . . . . . . . 117
3.5.1 Spannungsspiel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
3.5.2 Frequenz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
3.5.3 Größtkorn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
3.5.4 Betonfestigkeit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
3.5.5 Probenalter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
3.6 Berücksichtigung der Temperatur bei der Versuchsbewertung . . . . . . . . . . . 122
3.6.1 “Influence of temperature on the compressive strength of high performance
and ultra-high performance concretes“ Deutscher et al. (2021b) . . . . . . 123
3.6.2 “Consideration of the heating of high-performance concretes during cyclic
tests in the evaluation of results“ Deutscher (2021) . . . . . . . . . . . . . 134
3.6.3 Verifizierung an einem HPC . . . . . . . . . . . . . . . . . . . . . . . . . . 150
4 Zusammenfassung und Ausblick 153
4.1 Zusammenfassung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
4.2 Ausblick . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
5 Allgemeine Ergänzungen A1
5.1 Materialkennwerte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A1
5.1.1 UHPC 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A1
5.1.2 UHPC 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A3
5.2 Druckfestigkeit unter Temperatureinfluss . . . . . . . . . . . . . . . . . . . . . . . A4
5.2.1 Klimakammerlagerung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A4
5.2.2 Wasserlagerung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A5
5.2.3 getrocknet im Trockenofen . . . . . . . . . . . . . . . . . . . . . . . . . . . A5
5.3 zyklische Druckschwellversuche . . . . . . . . . . . . . . . . . . . . . . . . . . . . A5
5.3.1 UHPC 1 Charge I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A7
5.3.2 UHPC 2 Charge II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A11
5.3.3 UHPC 1 Charge III . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A16
5.3.4 Mörtel Charge IV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A20
5.3.5 NC 1 Charge V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A21
5.3.6 UHPC 1 Charge VI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A22
5.3.7 UHPC 1 Charge VII . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A23
5.3.8 NC 2 Charge VIII . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A28
5.4 Restfestigkeit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A30
5.4.1 UHPC 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A30
5.4.2 UHPC 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A31 / Due to ever slimmer and higher load-bearing structures the requirements on building materials are increasing. On the part of concrete, the development is therefore moving towards high-strength and ultra-high-strength concretes. In addition to the increasing static stress, the importance of fatigue strength is also increasing due to increasingly sophisticated constructions. Therefore, the focus in materials research is currently on resistance to cyclic stresses, especially in the area of high-performance concretes. Various reasearchers has been detected a heating of test specimens
at higher load-speed during pressure swell tests to generate Wöhler lines. For this reason, this study is focused on the heating in relation to ultra-high-strength concrete.
Using a comprehensive parameter study, an overview of the significant influencing variables on the heating process could be given. On the one hand, an internal friction potential which increases with decreasing maximum grain size and due to growing damage, could be indetified as an important causes of temperature generation. On the other hand, the applied energy per load cycle is decisive. Unlike the fatigue strength of concrete, which mainly depends on the maximum stress, the heating per load cycle is dependent on the amplitude. The load frequency only influences the measurable heating by changing the time period available per load change for
temperature release. But the heating per load cycle is independent of the load frequency.
A negative influence of the specimen heating could be observed in the significant reduction of the number of cycles to failure compared to tests in which there is no significant increase in temperature. Based on previous studies on high-strength concretes, various authors propose an adaptation of the test procedure to minimise the temperature development in the specimen. The present work proposes a method in which heating is allowed in favour of time-efficient testing and the maximum temperature is taken into account in the results. The static compressive strength,
which is temperature-dependent, could be identified as a main cause of premature failure in the case of strong heating. If the temperature increases, the compressive strength is reduced simultaneously. This leads to a change in the related stress cycle in force-controlled pressure swell tests with constant load cycle. The increasing related maximum stresslevel causes finally a premature fatigue failure. All tests that fail before the calculated expected value heat up until failure. This leads to a permanently changing stress amplitude over the duration of the test. In the evaluation, a changeable load cycle cannot be used for the classification in Wöhler
diagrams. Due to the fact that the use of the load input values leads to an underestimation of the fatigue strength, an equivalent constant stress cycle must be determined, which takes into account the strength change of the concrete. Based on the pressure swell tests carried out and the temperature-dependent compressive strength, an analytical method was developed. Using the initial load amplitude as well as the measured maximum temperature, an adjusted maximum stress level can be calculated. The achieved number of cycles to failure can be entered in a Wöhler diagram with the calculated maximum stress level. This method is finally verified for the ultra-high strength concrete investigated in further detail for a wide range of load configurations and additionally for test results of a high-strength concrete.:Inhaltsverzeichnis
1 Einleitung und Aufbau 1
1.1 Einleitung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.3 Aufbau der Arbeit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2 Stand des Wissens 5
2.1 Grundlagen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1.1 Ermüdungsbeanspruchung . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1.2 Betonermüdung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1.3 Ultrahochfester Beton (UHPC) . . . . . . . . . . . . . . . . . . . . . . . . 12
2.1.4 UHPC unter Ermüdungsbeanspruchung . . . . . . . . . . . . . . . . . . . 14
2.2 Einfluss der Temperatur auf die statische Druckfestigkeit . . . . . . . . . . . . . . 15
2.2.1 Wissenschaftliche Untersuchungen . . . . . . . . . . . . . . . . . . . . . . 15
2.2.2 Regelung nach fib Model Code 2010 (2012) . . . . . . . . . . . . . . . . . 17
2.3 Betonerwärmung bei zyklischen Versuchen – Wissensstand bis 2017 . . . . . . . . 18
2.3.1 Einflussparameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.3.2 Temperaturentwicklung im Probekörper . . . . . . . . . . . . . . . . . . . 23
2.4 Zielstellung der Arbeit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.5 Betonerwärmung bei zyklischen Versuchen - Wissensstand ab 2017 . . . . . . . . 24
2.5.1 Elsmeier - Parameterstudie zur Erwärmung von hochfesten Vergussbetonen 24
2.5.2 Bode - Energetische Auswertung von Ermüdungsversuchen . . . . . . . . . 28
2.5.3 Schneider - Frequenzeinfluss auf den Ermüdungswiderstand von hochfestem
Beton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.5.4 Markert - Feuchte- und Wärmeeinfluss auf die Ermüdungsschädigung von
HPC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
2.6 Zusammenfassung und Abgrenzung . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3 Eigene Forschung 37
3.1 Grundlagen zur Versuchsdurchführung . . . . . . . . . . . . . . . . . . . . . . . . 37
3.1.1 Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
3.1.2 Herstellung, Lagerungsbedingungen und Probekörpervorbereitung . . . . . 39
3.1.3 Probengeometrie und Messapplikationen . . . . . . . . . . . . . . . . . . . 39
3.1.4 Versuchsdurchführung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3.1.5 Betonchargen und Versuchsmatrix . . . . . . . . . . . . . . . . . . . . . . 42
3.2 Auswertung von Temperaturmesswerten . . . . . . . . . . . . . . . . . . . . . . . 44
3.3 Temperaturentwicklung und -verteilung im Probekörper . . . . . . . . . . . . . . 46
3.4 Parameterstudie . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
3.4.1 “Experimental Investigations on the Temperature Increase of Ultra-High
Performance Concrete under Fatigue Loading“ Deutscher et al. (2019) . . 49
3.4.2 “Experimental Investigations on Temperature Generation and Release
of Ultra-High Performance Concrete during Fatigue Tests“ Deutscher
et al. (2020a) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
3.4.3 “Heating rate with regard to temperature release of UHPC under cyclic
compressive loading“ Deutscher et al. (2021a) . . . . . . . . . . . . . . . . 86
3.4.4 “Influence of the compressive strength of concrete on the temperature
increase due cyclic loading“ Deutscher et al. (2020b) . . . . . . . . . . . . 98
3.4.5 Ergänzungen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
3.4.6 Zusammenfassung der Parameterstudie . . . . . . . . . . . . . . . . . . . . 116
3.5 Vergleich mit dem Stand des Wissens . . . . . . . . . . . . . . . . . . . . . . . . . 117
3.5.1 Spannungsspiel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
3.5.2 Frequenz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
3.5.3 Größtkorn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
3.5.4 Betonfestigkeit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
3.5.5 Probenalter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
3.6 Berücksichtigung der Temperatur bei der Versuchsbewertung . . . . . . . . . . . 122
3.6.1 “Influence of temperature on the compressive strength of high performance
and ultra-high performance concretes“ Deutscher et al. (2021b) . . . . . . 123
3.6.2 “Consideration of the heating of high-performance concretes during cyclic
tests in the evaluation of results“ Deutscher (2021) . . . . . . . . . . . . . 134
3.6.3 Verifizierung an einem HPC . . . . . . . . . . . . . . . . . . . . . . . . . . 150
4 Zusammenfassung und Ausblick 153
4.1 Zusammenfassung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
4.2 Ausblick . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
5 Allgemeine Ergänzungen A1
5.1 Materialkennwerte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A1
5.1.1 UHPC 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A1
5.1.2 UHPC 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A3
5.2 Druckfestigkeit unter Temperatureinfluss . . . . . . . . . . . . . . . . . . . . . . . A4
5.2.1 Klimakammerlagerung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A4
5.2.2 Wasserlagerung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A5
5.2.3 getrocknet im Trockenofen . . . . . . . . . . . . . . . . . . . . . . . . . . . A5
5.3 zyklische Druckschwellversuche . . . . . . . . . . . . . . . . . . . . . . . . . . . . A5
5.3.1 UHPC 1 Charge I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A7
5.3.2 UHPC 2 Charge II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A11
5.3.3 UHPC 1 Charge III . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A16
5.3.4 Mörtel Charge IV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A20
5.3.5 NC 1 Charge V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A21
5.3.6 UHPC 1 Charge VI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A22
5.3.7 UHPC 1 Charge VII . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A23
5.3.8 NC 2 Charge VIII . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A28
5.4 Restfestigkeit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A30
5.4.1 UHPC 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A30
5.4.2 UHPC 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A31
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Effect on Contact Resistance dueto Cross Connection of MC4 Compatible ConnectorTanguturi, Sai Kishan January 2018 (has links)
Electrical connectors are the blocks that connect solar panels together. Whenever a photovoltaic plant commences, the main discussion goes around on solar panels, inverters, charge controllers, etc. But the topic of connectors is usually hardly discussed. Connectors in a photovoltaic system can definitely contribute to improve the overall performance of the system, provided that importance is given while selecting the connectors. The electrical connectors used in photovoltaic systems can be connected in two possible ways. Connectors can be connected either in a pure-connection or in a cross-connection. Male and female connectors from the same brand results a pure-connection (P-C). Male and female connectors from two different brands results in a cross-connection (C-C). There have been discussions in photovoltaic, electrical connector markets and international solar events regarding the risks involved, losses and consequences due to a cross-connection. The main reason behind cross-connections is the unawareness of the installers in knowing the difference between a pure-connection and a cross-connection. Even though the installers are aware of this difference, they are not aware of the consequences of cross-connections. Multi-Contact, a leading electrical connector manufacturer of MC4 photovoltaic connectors affected by the counterfeit products of MC4, due to the sudden boom in the solar market during 2011-12. With the help of TÜV Rheinland, Multi-Contact conducted couple of tests namely temperature increase test and accelerated stress tests to understand the disadvantages of cross-connections. This thesis tried to replicate the tests performed by Multi-Contact in an attempt to understand the test results by using connectors that are used in the Swedish market. Performing temperature increase test and accelerated stress tests on most commonly used connectors in the Swedish market is the main aim of this thesis. The first test, gives an understanding of the temperature variations across various connector sets (four connector sets from various manufacturers used in this thesis) and the latter tests helps to understand the quality of the contact resistance of these connector sets. The four connector set manufacturers used in this test were Multi-Contact (MC), Weidmüller (WM), Blussun solar (BSS) and PBM. The quality of contact resistance of a connector is directly related to the quality of the connector set. During the 20 minutes of the temperature increase test, the connector set from WM performed better than its competitors in the P-C. Whereas, the MC-BSS connector set had performed well in the C-C. The connector type of male MC and female BSS showed its dominance throughout the test. Unfortunately, no conclusions were able to be drawn from this test results due to insufficient information about the test procedure. From the results of accelerated stress tests, the C-C set from MC outperformed its P-C counterpart. All ten connector sets used in this project passed the standard and qualified as connectors with good quality contact resistance. Therefore the best results out of only a P-C connector set does not seems to be completely true. With the standard used in this thesis, it is quite difficult to judge the quality of connectors. Rather than saying a P-C is superior and a C-C is inferior in terms of quality, there is a need to come up with a new method to evaluate the quality of connectors. Matching the connectors based on their tolerances could be a potential solution to the mismatching problem in connectors.
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Regulace přítlaku lamelových spojek dvouspojkové převodovky / Engagement Force Control of Multi-plate Clutches of Dual Clutch GearboxHorák, Josef January 2020 (has links)
The master’s thesis deals with ways of controlling starting clutches of cars, especially of DQ200 gearbox, which contains dry disc clutches. The introduction describes basic principles of torque transfer and amount of clutch force. Then the description of construction of starting clutches and ways of controlling clutch types mentioned beforehand is given. In the next part of the thesis, wide spectrum of control methods is measured, from which a certain part is selected. This is followed by driving tests and based on driving data, one method of the clutch control is chosen. Then those control methods from narrow selection are tested for acoustic impact in the cabin of the car. In the end the best way of clutch control is selected. The selection based on driving data and acoustic measurement.
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Modeling The Temperature of a Calorimeter at Clab : Considering a Thermodynamic Model of The Temperature Evolution of The Calorimeter System 251Ekman, Johannes January 2021 (has links)
It is important to know the heat generated due to nuclear decay in the final repository for spent nuclear fuel. In Sweden, the heating powers generated in spent nuclear fuels are currently measured in the calorimeter System 251 at the Clab facility, Oskarshamn. In order to better measure, and increase understanding, of the temperature measurements in the calorimeter, a simple thermodynamic model of its temperature evolution was developed. The model was described as a system of ordinary differential equations, which were solved, and the solution was applied to calibration measurements of the calorimeter. How precise the model is, how its parameters affect the model, et cetera, are addressed. How the temperature evolution of the system changes as the values of parameters in the model are changed is addressed. The mass correction of the calorimeter could be estimated from this model, which validated the established mass correction of the calorimeter. How the measurement results from the calorimeter would be affected if the volume of the calorimeter was changed was also considered. Additionally, gamma radiation escape from the calorimeter without being detected as heat in the calorimeter. The gamma escape energy fraction was estimated by SERPENT simulations of the calorimeter, as a function of the initial photon energy. The gamma escape was also estimated for different values of the radius of System 251.
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