Dissertations / Theses: 'Plastiska deformationer'

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Pettersson, Torbjörn. "OMBYGGNAD AV TRAFIKPLATS : Ekhagsmotet i Jönköping." Thesis, Jönköping University, JTH, Civil Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-10491.

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Marko, Vilotić. "Intenzivna plastična deformacija u procesima višefaznog sabijanja materijala." Phd thesis, Univerzitet u Novom Sadu, Fakultet tehničkih nauka u Novom Sadu, 2015. http://www.cris.uns.ac.rs/record.jsf?recordId=95538&source=NDLTD&language=en.

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Predstavljena je nova metoda intenzivne plastične deformacije – višefazno sabijanje V-alatom. Koristeći ovu metodu, sabijanjem u osamnaest faza, unapređene su mehaničke osobine niskougljeničnog čelika Č.1221 – tvrdoća, čvrstoća i deformabilnost. Za ispitivanje mikrostrukture korišćeni su svetlosni, skening i transmisioni mikroskop. Prosečna veličina kristalnog zrna početnog materijala od 19 mikrometara je smanjena na 250 nanometara nakon dvanaest faza sabijanja. Nakon osamnaest faza sabijanja na čelu uzorka ostvarena je ukupna deformacija u iznosu od 3,38.
A new severe plastic deformation method has been presented - multistage upsetting by V-shape dies. By using this method, in eighteen upsetting stages, mechanical propreties (hardness, strenght and formability) of C15E low carbon steel has been improved. For microstructure analysis light, scanning and transmission microscopes have been employed. Initial average grain size of 19 μm has been reduced to 250 nm after twelve upsetting stages. After eighteen upsetting stages, total effective deformation at the sample forehead of 3,38 has been obtained.

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Langschwager, Kay [Verfasser], Matthias [Akademischer Betreuer] Oechsner, and Michael [Akademischer Betreuer] Vormwald. "Lokales Deformations- und Schädigungsverhalten zyklisch elastisch-plastisch beanspruchter Schweißverbindungen / Kay Langschwager ; Matthias Oechsner, Michael Vormwald." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2020. http://d-nb.info/1211088588/34.

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Aastorp, Knut Iver. "Plastic Deformation at Moderate Temperatures of 6XXX-series Aluminium Alloys." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Natural Sciences and Technology, 2002. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-118.

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The present work has been carried out in order to investigate Al-Mg-Si alloys that are deformed at moderate temperatures. These temperatures are in the range between 200 C and 300 C. Also some experiments are performed at room temperatures. Two deformation models have been applied in the experiments: material deformation by compression testing and by forward extrusion.

The investigated alloys are AA6063, AA6082 and an alloy that is named “Alloy R” in this work. The latter alloy is the industrial alloy AA6082 without the Mn-addition (0.56wt%Mn in the AA6082). The “R” denotes the recrystallized microstructure in the material after hot forming operations.

The investigations show the effect of changing the temperature in the given temperature interval on the stress-strain relationship for each alloy. From the compression testing, it is found that none of the alloys AA6063 or Alloy “R” reaches a steady state condition as true strain approaches 0.8 for deformation temperatures between 200 C and 250 C. At compression testing performance at 300 C, the alloy “R” reaches a steady state condition at a true strain equal to 0.4.

As true stress-true strain relationship has been investigated for the “Alloy R” and the AA6063 at comparable deformation parameters, it is shown that the alloy “R”, with the highest Si-content, requires the highest true stress for a given true strain value (AA6063: 0.45wt%Si, Alloy “R”: 0.87wt%Si).

From the compression testing, the effect of Mn on the material properties in the AA6082-alloy has been determined. For the Alloy “R” and the AA6082, the true stress reached the same value after a certain amount of deformation. As deformation temperature increases, this common value of true stress corresponds to a decrease in true strain.

The AA6082 and Alloy “R” are also compared in experiments performed in forward extrusion. One observes that for the same deformation temperature and at identical die diameters, the ram force is identical. It is worth noticing that these alloys did not show the same relationship during the compression testing at low values of true strain (<0.8). On a microscopic scale, one concludes that Mn has no significant effect on the stress-strain relationship for the applied deformation parameters in the forward extrusion equipment.

Hardness measurements indicate that the age hardening potential in the extruded test specimen decreases as the deformation temperature increases. The hardness data is similar for both the AA6082 and the Alloy R, thus indicating that the Mn content has no significant effect on the strength of the material.

The deformed material has been annealed in order to investigate the recrystallization process in the AA6082 and the Alloy “R”. The recrystallization grain size in the Alloy “R” is significantly larger than in the AA6082 at comparable deformation parameters after annealing at 530 C for 15 minutes. This result is due to the effect of Mn-containing dispersoids in the AA6082. The recrystallization grain size in the Alloy “R” seems to be unaffected by the deformation temperature after annealing for 15 minutes. The observation of the AA6082 is quite different. A small increase in grain size is observed for both reduction ratios as the deformation temperature is elevated from 20C to 200 C and further to 250 C. At extrusion temperatures of 300 C the recrystallization grains are significantly larger.

Annealing experiments performed at 430 C on the AA6082 indicates that a change in the deformation temperature from 200 C to 250 C does not affect the amount of stored energy in the material significantly.

The Forge2 programme has been used to perform numeric simulations of the forward extrusion experiment. From this the temperature distribution, strain rate variation and true strain development in the test piece had been investigated. As the simulated true strain values are compared to the grain size in the annealed material, the recrystallization grain size is related to the amount of stored energy in the material in a very convincing way. It is also shown that the recrystallization grain diameter is related to the amount stored energy as the grain diameter is investigated in the radial and the extrusion direction separately.

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Motylenko, Mykhaylo. "Beitrag zur Analyse von Disklinationsstrukturen in plastisch verformten Metallen." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2011. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-67416.

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Gegenstand der Arbeit ist die Analyse der bei hohen Verformungsgraden in Werkstoffen durch kollektive Bewegung der Versetzungen entstandenen neuen Defektkonfigurationen, die auf der mesoskopischen Skala agieren. Diese so genannte Disklinationen rufen neben starken Gitterdehnungen auch erhebliche lokale Gitterrotationen hervor. Es wurde der Nachweis der Existenz der Disklinationen in plastisch verformten Kristallen geliefert sowie die qualitative und quantitative Analyse der Disklinationskonfigurationen und der Disklinationsstärke durchgeführt. Die Untersuchungen an stark verformten Ein- und Vielkristallen wurden mittels sowohl lokalen Methoden der Transmissions- (TEM, CBED) und Rasterelektronenmikroskopie (REM, EBSD) als auch der integralen Methoden der Röntgenstrukturanalyse (XRD) durchgeführt. Die Ergebnisse haben gezeigt, dass die Entwicklung der Zellblockstruktur mit erheblichem Anstieg der Desorientierungen und Versetzungsdichten in Versetzungswänden verbunden ist und durch die Bildung der Netzwerke von Disklinationen gefördert wird.

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Leiss, Bernd. "Strukturbezogene Textur- und Korngefügeuntersuchungen plastisch deformierter Dolomitgesteine am Südwestrand des Damara Orogens (Namibia) : Mechanismen der Texturbildung und ihre kinematische Bedeutung; mit 7 Tab. /." Stuttgart : Schweizerbart, 1996. http://www.gbv.de/dms/goettingen/191563315.pdf.

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Štěpánek, Roman. "Teplotní stabilita Mg-slitiny AZ91 připravené pomocí intenzivní plastické deformace." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230220.

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This thesis dealt with thermal stability of magnesium alloy AZ91 prepared by severe plastic deformation, which leeds to fine grained structure. This structure is characterised by its inherent instability and this thesis tries to find out the value of critical temperature and rate of this instability, which manifests as grain coarsening.

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Mohammadi, Ramona. "Verifieringsmetod för flexibla avgasledande element - Felmodsanalys." Thesis, KTH, Maskinkonstruktion (Inst.), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-192488.

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Detta examensarbete utfördes på Scania CV AB och behandlar delar i lastbilens avgassystem som utsätts för korrosion och nötning. Huvudmålet med detta arbete är att utveckla en provmetod för livslängdsundersökning av flexibla slangar. En serie tester utfördes för att förstå grundorsakerna till brott och en FE-analys utfördes för att verifiera resultaten till dessa prov. En stor del av den flexibla slangen blir stel på grund av höga avgastemperaturer och som leder till plastisk deformation av slangen. Men de tre första lindningarna som ligger närmast motorn behåller sin flexibilitet på grund av kontinuerliga motorvibrationer. Slutsatsen är att huvudorsaken som gör att de flexibla slangarna går av, är slitage som leder till sprickinitiering. Den sprickan sprider sig i form av lågcykelutmattning d.v.s att det tar ganska kort tid tills brott sker i den flexibla slangen. Korrosion initierar mellan de icke-flexibla delar av slangen Korrosionshastigheten ökar med tiden och det orsakar små hål på ytorna. Baserat på testresultaten är den mest lämpliga stället för livslängdsundersökningar Scanias komponentprovceller. Genom att mäta slitagedjupet under repeterbara förhållanden som rekommenderas i rapporten och med hjälp av data från kundutfall, kan en livslängd uppskattas. För att kunna förbättra livslängden för de flexibla slangarna, rekommenderas att använda rostfritt stål typ 1.4828 vid tillverkning av dessa slangar bör varmformning användas, samt att avståndet mellan lagrena respektive tjockleken ökas. Flera tester med olika teststidsintervall behöver göras för att ta reda på nötningshastigheten.
This thesis was conducted at Scania CV AB with information based on corrosion and wear. The main goal of this work is to develop a test method to investigate the stripwounded hose’s lifetime. A series of tests were performed to understand the reasons of their failure and a FE analysis was performed to verify the results obtained from these tests. It was observed that a large part of stripwounded hose becomes stiff due to high temperatures of the exhaust gas. The high temperature leads to plastic deformation of the hose. In contrast, the three first windings closest to the engine keep their flexibility due to continuously engine vibrations while there is sign of wear between the layers in these three windings more than other parts of the stripwounded hose. Hence, it is concluded that the main reason for stripwounded hose’s unpredictable failures is wear which leads to crack initiation. The crack propagation is in type of low cycle fatigue which means that it takes a short time until the stripewounded hose breaks. Corrosion is initiated between the non-flexible parts of the hose. The rate of corrosion is increased by time and causes small holes on the surfaces. According to results from the experiments the most suitable location for the lifetime investigation is Scania’s component test cells . Several tests with different time spans needs to be performed. By measuring the wear depth rate under repeatable test conditions and bycomparing with stripwounded hoses from customer trucks, a lifetime can be estimated. To improve the fatigue lifetime of the stripwounded hoses, it is recommended to use stainless steel of type 1.4828, manufactured through hot-forming with larger distance between layers and thicker layers to find out the wear rate.

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Kubiš, Milan. "Optimalizace sběrného výfukového potrubí Škoda 1,2 MPI." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-230446.

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The subject of this diploma thesis is optimalization of exhaust manifold of ŠKODA 1,2 MPI engine with respect for the plastic deformation at heat stress. The first part is focused on general description of converter module, whose component the exhaust manifold is. In the next part of the thesis is computation of a heat load of the exhaust manifold. The last part is devoted to the seal analysis of the whole converter module of a ŠKODA three-cylinder engine.

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Valeš, Jan. "Počítačová simulace kolapsu budovy zplastizováním kloubů." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2012. http://www.nusl.cz/ntk/nusl-225731.

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The aim of the thesis is to create an analytical 2D model of a multi-storey building and its consequent loading until the point of collapse which occures due to formation of plastic hinges. The first part is going to present a linear analysis of the problem; it focuses on location and level of load when the plastic hinges are formed. Then a nonlinaer analysis is going to be performed by RFEM programme using postcritical analysis and dynamic relaxation. Differences between the results of mentioned types and methods of analysis are going to be compared and an impact of variables is going to be evaluated .

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Třeštík, Jakub. "Výroba pouzdra pružiny protlačováním za studena." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229013.

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TŘEŠTÍK Jakub: Metal forming production of spring bush by cold extrusion. The Master’s degrese project, 2nd form, summer semester, academic year 2009/2010, educational group 5O/60, Mechanical Engineering – Manufacturing Technology, Brno University of Technology, Fakulty of Mechanical Engineering, Institute of Manufacturing Technology, Dept. Of Metal Forming and Plastic, May 2010. This project sloves the manufacturing proces sof “Spring bush” part by technology of cold extrusion. Part is made of 12 122.3 steel. Semifinished product has a cylinder shape with dimensions O29-24 mm. This part is made during four bulk forming operations on the TPZK 25 Šmeral Brno, a.s.

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Hrouzková, Andrea. "Optimalizace výrobní a montážní technologie ventilového čepu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229205.

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The thesis aimed to study the impact of manufacturing and assembly technology, the valve bolt fitted to diesel high pressure pump CP3 in the Bosch, which has been found to leak. As experimental material was chosen heat treated bolts M16x1,5 made of material 12 050th. Groups of samples were produced in two ranges hardness. Experimental determination of the optimum range of hardness was assessed on the basis of the results of the process of the screw and set the value of plastic deformation of the sealing surfaces of the parts. Experimental section also deals with the analysis of bearing surfaces on the pump and the components, after the screw process. To some extent, is observed as surface treatment

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Popelka, Zdeněk. "Analýza mechanismu tvoření třísky při obrábění titanových slitin." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229475.

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The diploma thesis focuses on analysis of mechanism of chip formation during machining of titan alloys. Application of titan alloys in metal-working and engineering industry is currently very significant topic. The mechanism of titan chip formation is dissimilar to steel and its foundation plays an important role in optimization of cutting process.

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Gonev, Trajce, and Ahmed Karabegovic. "Omkonstruktion av slanghållare till en lastvagn för diskdesinfektorer för att effektivisera och säkerställa rengörings- och desinfektionsprocessen." Thesis, Linnéuniversitetet, Institutionen för maskinteknik (MT), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-68024.

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Biologiskt kontaminerade medicinska instrument utgör en risk för att orsaka sjukdomar, och i förebyggande syfte används bland annat diskdesinfektorer för att rengöra och desinficera dessa instrument.Uppdragsgivaren Getinge Disinfection AB i Växjö vill effektivisera och säkerställa rengörings- och desinfektionsprocessen genom att konstruera en ny slanghållare, vilket även är syftet med detta arbete. Arbetet utförs med den ingenjörsvetenskapliga konstruktionsmetoden.Resultatet är en slanghållare som består av en klämma och en klämma-hållare, samt detaljritningar för prototyptillverkning, se Bilaga 14 och 15.Slutsatserna för slanghållaren är att risken för plastisk deformation har minimerats, att slanghållaren kan hålla i slangar med olika diametrar effektivt och säkert, att slanghållarens klämma är lätt att ersätta, samt att klämman kan vara överdimen-sionerad.Avslutningsvis är slutsatsen att den nya slanghållaren kan bidra till att effektivisera och säkerställa rengörings- och desinfektionsprocessen av anestesislangar

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Dymáček, Martin. "Možnosti odstranění zbytkových napětí v tenkých pásech pomocí tahového rovnání." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229030.

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Tension leveling is a process used in the steel industry in order to eliminate any shape imperfections of cold-rolled thin strips. The master thesis deals with developing a computer program that generates basic parameters of tension leveling line. The theoretical part of the thesis summarizes the types of the shape imperfections in strips, their causes and the principles of their elimination. This part also presents the mechanism of tension leveling and describes the present-day design of tension levelers. The practical part of the thesis starts with an analytical description of stress-strain behaviour of strip during tension leveling (supposing the simplified conditions). A computer program that allows devising basic parameters of tension leveling line is created on the basis of these analytical relations. The program results are successfully verified by numerical model based on the finite element method (FEM) created in the program ANSYS. Then the interdependencies of certain input and output parameters of created program are determined. These interdependencies can be used as effective design of tension leveling lines.

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Poláček, Milan. "Optimalizace parametrů dynamické relaxace při řešení mezních plastických stavů konstrukcí." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226797.

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The aim of the thesis is to create an analytical model of frame construction. Determining load at which individual plastic hinges are formed until the collapse of the structure. The analysis is going to be performed by RFEM with an additional module RFDYNAM. Subsequently, the parameters of dynamic relaxation is going to be optimized to specify and speed up the calculations. Finally, the optimized parameters is going to be used to analyze the storeyed frame construction formed Ing. Jan Vales including a comparison of findings.

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Darida, Jiří. "Mechanické vlastnosti hořčíkové slitiny AZ91E připravené metodou ECAP." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-254287.

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This thesis deals with mechanical and fatigue properties of magnesium alloy AZ91 processed by EX-ECAP method. This method involves the application of extrusion followed by equal-channel angular pressing. To obtain basic mechanical characteristics, the tensile test were carried out at room and elevated temperatures. Further the fatigue tests were performed and obtained data were used to compile S-N curve. The work also includes metallographics analysis of microstructure and fractographic analysis of fracture surfaces of tensile and fatigue test specimens.

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Poloprudský, Jakub. "Struktura a mechanické vlastnosti materiálů na bázi hořčíku zpracovaných metodou HPT." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-400834.

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This thesis is focused on processing of pure magnesium by high pressure torsion method (HPT). This process belongs to the group of intensive plastic deformation methods (SPD). SPD methods are in the centre of scientific interest for several decades. Theoretical part of this thesis puts an effort to summarize basic knowledge and principles of SPD methods with extra focus on method HPT. As theoretical part continues magnesium as technical material is presented. Influence of SPD on use and properties of pure magnesium is then presented. This trend is further developed in effort to describe the effect of individual HPT process variables on the properties of pure magnesium and its alloys. Focus of practical part of this thesis is in influence of number of revolutions. Samples were processed at 1/8, 1/4, 1/2, 1, 4 and 8 turns at room temperature. Speed of process was 1rpm and applied pressure was 6 GPa. The structure of commercially pure magnesium prepared by casting and moulding were observed with focus on differences caused by input material. The structure was observed by both light microscopy and back scattered electron diffraction (EBSD), focusing on structure development, grain size and grain orientation. Compared to other works on similar topic, the emphasis here is on observing the microhardness on the vertical edge of the sample. The hardness shows a steep increase right after 1/8 of a turn. With increasing number of turns gradual homogenization of microhardness is presented accompanied by slight decrease in microhardness. No trend in microhardness relative to the distance from anvil has occurred. Structure observed with EBSD shows a bimodal character with larger grains oriented in the same direction. The three-point bending test didn’t end up as expected, and the approach to evaluation of magnesium-based HPT needs to be re-evaluated for future work. A three-point bending test was designed for the initial assessment of the basic mechanical properties of the material.

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Grygařík, Václav. "Návrh turbínové skříně pro diagonální turbínové kolo." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-254418.

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This thesis is focused on design of the turbine housing CAD model applicable for mixed flow turbine. It also deals with strength analysis of designed turbine housing. The aim of the thesis is to create a three-dimensional turbine housing model accompanied by drawings.

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Man, Ondřej. "Aplikace metody difrakce zpětně odražených elektronů v materiálovém inženýrství." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-233915.

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The thesis deals with principles and common applications of the electron backscatter diffraction (EBSD) method. Some practical experience in application of the method to a study of highly deformed structure of copper and its thermal stability is described on one hand, and, on the other hand, to a study of phase composition of TRIP steel on various levels of imposed strain. The limitations of EBSD method are discussed along with its resolution in comparison with other complimentary techniques.

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Langschwager, Kay. "Lokales Deformations- und Schädigungsverhalten zyklisch elastisch-plastisch beanspruchter Schweißverbindungen." Phd thesis, 2020. https://tuprints.ulb.tu-darmstadt.de/11738/1/Langschwager_Dissertation_Lokales%20Deformations-%20und%20Sch%C3%A4digungsverhalten%20zyklisch%20elastisch-plastisch%20beanspruchter%20Schwei%C3%9Fverbindungen.pdf.

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Für eine wirtschaftliche Bauteilauslegung sind rechnerische Methoden, wie die Finite-Elemente- Analyse, etablierte Verfahren. Bei der Lebensdaueranalyse zyklisch belasteter Schweißverbindungen ist das sogenannte örtliche Konzept, das auf der Finiten-Elemente-Analyse basiert, ein gängiges Vorgehen um übermäßige Konservativität zu vermeiden. Beim örtlichen Konzept werden die wesentlichen Geometriemerkmale der belasteten Schweißverbindungen nachgebildet und die Vergleichsspannung am Ort der höchsten Beanspruchung bestimmt. Eigene Untersuchungen haben gezeigt, dass nicht nur die Geometrie der Schweißverbindung einen signifikanten Einfluss auf die Lebensdauer der Schweißverbindung besitzt, sondern auch ihre lokalen Werkstoffeigenschaften, die somit berücksichtigt werden müssen. Der Einfluss der lokalen Werkstoffeigenschaften auf die Lebensdauer von Schweißverbindungen zeigt sich vor allem bei nachbearbeiteten Geometrien, wo alle geometrischen Schweißnahtmerkmale durch Abschleifen entfernt sind. Dort tritt trotz der entfernten Geometrieimperfektionen eine reduzierte Lebensdauer der Schweißverbindung im Vergleich zu der Lebensdauer der eingesetzten Werkstoffe – Grundwerkstoff und Schweißzusatzwerkstoff – ein. Die eingesetzten Werkstoffe sowie die Parameter des Schweißprozesses bestimmen maßgeblich, wie stark die Lebensdauer reduziert wird. Lokale Werkstoffinhomogenitäten führen in der Regel zu Spannungsüberhöhungen und damit zu einer reduzierten Lebensdauer der Bauteile. Um die resultierende Lebensdauer richtig rechnerisch bewerten zu können, sind die bestimmenden Werkstoffeigenschaften zu quantifizieren. Ziel dieser Arbeit ist die Quantifizierung lokaler Werkstoffeigenschaften am Beispiel einer austenitischen Schweißverbindung und die Bewertung dieser Eigenschaften in Hinblick auf die Lebensdauer geometrisch unterschiedlicher Schweißverbindungen. Zur Quantifizierung lokaler Werkstoffkennwerte gibt es unterschiedliche Strategien. Eine Strategie ist die Kennwertermittlung anhand von Miniaturproben, die aus den unterschiedlichen Bereichen der Schweißverbindung gefertigt werden. Da die Herstellung und Prüfung dieser Proben sehr kosten- und zeitintensiv ist, werden in dieser Arbeit die einzelnen Werkstoffe sowie die Schweißverbindungen im Ganzen charakterisiert. Eine weitere Strategie ist die Ableitung von Kennwerten aus anderen Prüfmethoden – z. Bsp. einer flächigen Härtemessung. Dabei tritt die Frage auf, ob eine Umrechnung zwischen den unterschiedlichen Werkstoffkennwerten möglich ist – Härte zu zyklischer Festigkeit. Weiterhin zeigen eigene Untersuchungen, dass die Härteverteilung entlang der untersuchten Schweißverbindung nicht mit anderen lokalen Charakteristiken, wie der Mikrostruktur, einhergeht. Somit tritt ebenfalls die Frage nach der tatsächlichen Verteilung der lokalen zyklischen Werkstoffeigenschaften auf. Hierzu wird in dieser Arbeit eine optische Methode eingesetzt, um die Werkstoffeigenschaften mit Hilfe der Digitalen Bildkorrelation zu identifizieren. Die flächig ermittelten Verformungen entlang der geschweißten Proben werden genutzt, um in einem Postprozessing die zyklischen Werkstoffkennwerte zu ermitteln. Eine identifizierte lokale Werkstoffeigenschaft weist eine direkte Korrelation zur Härtemessung, wohingegen eine andere mit der Mikrostruktur korreliert. Damit lässt sich neben der reduzierten Lebensdauer der Schweißverbindungen auch der Schweißprozess besser verstehen und beurteilen. Die erfassten Werkstoffeigenschaften und damit auch das konzeptionelle Vorgehen zur Bestimmung der Eigenschaften werden einerseits mit Hilfe der globalen Grundcharakterisierung der einzelnen Werkstoffe und andererseits anhand wärmebehandelter Proben validiert.

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Krajňák, Tomáš. "Studium jemnozrnných materiálů připravovaných metodou intenzivní plastické deformace." Doctoral thesis, 2015. http://www.nusl.cz/ntk/nusl-350058.

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Title: Study of ultrafine-grained materials prepared with different methods of severe plastic deformation Author: RNDr. Tomáš Krajňák Department: Department of Physics of Materials, Faculty of Mathematics and Physics, Charles University in Prague Supervisor: Doc. RNDr. Kristián Máthis, PhD., Department of Physics of Materials, Faculty of Mathematics and Physics, Charles University in Prague Abstract: Interstitial free steel with ultrafine-grained (UFG) structure was prepared by high-pressure torsion (HPT). The development of the microstructure as a function of the number of HPT turns was studied at the centre, half-radius and periphery of the HPT-processed disks by X-ray line profile analysis (XLPA), positron annihilation spectroscopy (PAS) and electron microscopy. The dislocation densities and the dislocation cell sizes determined by XLPA were found to be in good agreement with those obtained by PAS. The evolution of the dislocation density, the dislocation cell and grain sizes, the vacancy cluster size, as well as the high-angle grain boundary (HAGB) fraction was determined as a function of the equivalent strain. It was found that first the dislocation density saturated, then the dislocation cell size reached its minimum value and finally the grain size got saturated. For very high strains after the...

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Bajer, Jan. "Mikrostruktura a mechanické vlastnosti hliníkových slitin po intenzivní plastické deformaci." Master's thesis, 2015. http://www.nusl.cz/ntk/nusl-347191.

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New technologies of components assembling in car and aircraft industries and requests on improved mechanical and corrosion properties of metallic materials in the packing industry activate the utilization of highly innovative and unconventional manufacturing processes. There are only a limited number of processing, that retain the original material thickness and in an appropriate manner modify material properties. These are different types of annealing, severe plastic deformation methods or combination of both. In recent years constrained groove pressing (CGP) was devoloped with this method the grain size can be reduced from tens of micrometers to sub-micrometers. The present work is focused on a study of evolution of microstructure and mechanical properties of two alloys based on EN AW 3003 after CGP deformation and subsequent annealing.

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Motylenko, Mykhaylo. "Beitrag zur Analyse von Disklinationsstrukturen in plastisch verformten Metallen." Doctoral thesis, 2009. https://tubaf.qucosa.de/id/qucosa%3A22759.

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Gegenstand der Arbeit ist die Analyse der bei hohen Verformungsgraden in Werkstoffen durch kollektive Bewegung der Versetzungen entstandenen neuen Defektkonfigurationen, die auf der mesoskopischen Skala agieren. Diese so genannte Disklinationen rufen neben starken Gitterdehnungen auch erhebliche lokale Gitterrotationen hervor. Es wurde der Nachweis der Existenz der Disklinationen in plastisch verformten Kristallen geliefert sowie die qualitative und quantitative Analyse der Disklinationskonfigurationen und der Disklinationsstärke durchgeführt. Die Untersuchungen an stark verformten Ein- und Vielkristallen wurden mittels sowohl lokalen Methoden der Transmissions- (TEM, CBED) und Rasterelektronenmikroskopie (REM, EBSD) als auch der integralen Methoden der Röntgenstrukturanalyse (XRD) durchgeführt. Die Ergebnisse haben gezeigt, dass die Entwicklung der Zellblockstruktur mit erheblichem Anstieg der Desorientierungen und Versetzungsdichten in Versetzungswänden verbunden ist und durch die Bildung der Netzwerke von Disklinationen gefördert wird.

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Németh, Gergely. "Studium slitin titanu s využitím neutronové difrakce." Doctoral thesis, 2021. http://www.nusl.cz/ntk/nusl-449111.

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Title: Investigation of titanium alloys using neutron diffraction Author: Gergely Németh Department / Institute: Department of Physics of Materials Supervisor of the master thesis: prof. RNDr. Kristián Mathis, Ph.D., DrSc., Department of Physics of Materials Abstract: Titanium grade 2 was treated by multiple passes of the continuous equal- channel angular pressing technique (CONFORM ECAP) and, after each pass, additionally by rotary swaging. The residual strain field in samples processed by only CONFORM ECAP was studied by neutron diffraction strain scanning. In order to elucidate the microscopic background and calculate the related residual stress field, the local microstructure was thoroughly investigated by various experimental techniques. The microstructure and the deformation behavior of the rotary swaged samples was studied by transmission electron microscopy and by in-situ neutron diffraction during compression. The results of the analyses indicated that microstructural gradients were present in the material as the result of the inhomogeneous deformation during the CONFORM ECAP treatment. These gradients were identified as the main reason of the presence of residual stress fields. The distributions of stress fields calculated based on microstructural parameters were in correlation with simulation...

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Vlasák, Tomáš. "Mikrostruktura a teplotní stabilita ultra jemnozrnných Mg-Zn-Y slitin." Master's thesis, 2017. http://www.nusl.cz/ntk/nusl-368163.

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The aim of this diploma thesis is to investigate microstructure and thermal stability of ultra fine grained magnesium alloys. The thesis first summarises methods using plastic deformation in order to achieve ultra fine grained structure that are used to process metals. Then experimental methods employed in the experimental part including microhardness testing, scanning electron microscopy and positron annihilation spectroscopy are described. Brief summary of previous research on MgZnY alloys strengthened by quasicrystalline phases and Mg22Gd alloys is given. Finally, results of experimental investigation of MgZnY alloys with various Zn/Y ratios and Mg22Gd alloy are discussed. These results suggest that presence of phases in MgZnY alloys depend on Zn/Y ratio, hardness of these alloys depends on Zn content and that rapid cooling of MgZnY alloys annealed at 500 řC lead to significant increase in volume fraction of quasicrystalline icosahedral phase. In the second section of the experimental part thermal behaviour of Mg22Gd alloy is investigated. Furthermore, formation of GdH2 particles in Mg22Gd is examined and attributed to reaction of hydrogen decomposed from water vapour with gadolinium in areas rich in gadolinium. Finally, significant hardening of Mg22Gd alloy processed by high pressure torsion has been...

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Pribylincová, Natália. "Vliv kyseliny askorbové na parametry rovnice lisování." Master's thesis, 2013. http://www.nusl.cz/ntk/nusl-323784.

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Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Student: Natália Pribylincová Consultant: Doc. RNDr. Milan Řehula, CSc. Effect of ascorbic acid on the parameters of compression equation Many mathematical models describing the compressing process are widely used in the development of new medicinal products in form of tablets. This process can be evaluated by means of compaction equations or throughout the viscoelastic properties. Compaction equation expresses dependency on height, volume or density of the used material which is being compressed by the applied compacting pressure. Based on the gained parameters, it is possible to describe specifically various stages of the compaction process, to determine characteristic properties of the studied material and accordingly to examine its mechanism. This thesis deals with the impact of the ascorbic acid on the parameters of compaction equation. The paperwork evaluates a mixture consisting of ascorbic acid (AA) and microcrystalline cellulose (MCC) in the ratio of MCC : AA 100:0, 75:25, 50:50, 25:75, 0:100. . The mostly used compression equations are described in the theoretic part. The three - exponential equation by Řehula created at the Department of Pharmaceutical Technology at Charles...

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Tisoňová, Zuzana. "Vliv ibuprofenu na parametry rovnice lisování." Master's thesis, 2013. http://www.nusl.cz/ntk/nusl-323802.

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Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Student: Tisoňová Zuzana Consultant: Doc. RNDr. Milan Řehula, CSc. Compacting process is mathematically expressed by compression equations. It is characterized by various parameters of equations. The equation expresses the dependence of the volume, density and height on compacting pressure. In this paperwork, the parameters of compacting equation are evaluated and the pre-loading phase, the phase of elastic deformation and the phase of plastic deformation are studied. This thesis deals with impact of ibuprofen on the parameters of compaction equation. Five mixtures which included microcrystalline celulose and ibuprofen in different ratio 100:0, 75:25, 50:50, 25:75 and 0:100 were studied. Results were based on the three-exponential equation. They were evaluated thanks to box plots. From the results obtained, it is obvious that with decreasing amount of microcrystalline cellulose, the parameter a1 has increased and the parameter E1 also slightly has increased. The composition of the used material didn't have any huge influence on parameters 1/t1 and pH1. During the phase of elastic deformation, the parameters a2 and E2 with decreasing amount of ibuprofen have decreased. On the other hand, the...

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Šmíd, Jakub. "Vliv kyseliny acetylsalicylové na parametry rovnice lisování." Master's thesis, 2013. http://www.nusl.cz/ntk/nusl-325231.

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Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Student: Jakub Šmíd Consultant: Doc. RNDr. Milan Řehula, CSc. Effect of acetylsalicylic acid on the parameters of compression equation Compacting process can be expressed mathematically by compression equations. It is characterized by various parameters. The compression equation expresses the dependence of the volume, density and height on compacting pressure. This paper evaluates the parameters of the compaction equation and study pre-loading phase, the phase of elastic deformation and the phase of plastic deformation. This thesis examines effect of acetylsalicylic acid on the parameters of compaction equation. Tablets were compressed from five mixtures. Mixtures contained acetylsalicylic acid and microcrystalline cellulose in different ratios 0:100, 25:75, 50:50, 75:25 and 0:100. The results were obtained using the three-exponential equation. Evaluation was carried out by using box plots.

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Černá, Pavlína. "Ověření nové metody na hodnocení stresové relaxace tablet." Master's thesis, 2013. http://www.nusl.cz/ntk/nusl-325236.

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Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical technology Supervisor: Doc. RNDr. Milan Řehula, CSc. Title of Dissertation: Validation of a new method for the evaluation of stress relaxation of tablets Keywords: tablets, stress relaxation test, elastic and plastic deformation The theoretical part of this thesis deals with the elastic relaxation of tablets. It describes various methods used in the evaluation of elastic recovery of tablets. The present work explores the factors affecting the elastic relaxation of tablets. The experimental part is focused on the stress relaxation test. Until present only one delay was studied. This work studies the stress relaxation after relieving tablet. The parameters A2, T2 and P2 were reviewed. The relationship between the parameters P2 and compression force relief were studied. For experiments microcrystalline cellulose Avicel PH 102 (MCC) was used. Tablets were compressed in a device used for testing the strength of the material in pressure and tension T1-FRO 50. For the determination of the stress relaxation test, the tablets were compressed with 180 sec first delay. The second delay was always 60 sec but it was measured from certain decrease of pressure (7 kN, 6 kN, 5 kN, 4 kN, 3 kN, 2 kN, 1 kN and 0.1 kN). To...

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Mařanová, Lucie. "Vliv paracetamolu na parametry rovnice lisování." Master's thesis, 2013. http://www.nusl.cz/ntk/nusl-330101.

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Evaluation of the tableting mixtures containing the paracetamolum by the parameters of the equation of compression The diploma thesis deals with effect of paracetamol on the parameters of compression equation. These parameters characterize compression process in the individual phases of compression: precompression phase, phase of elastic deformation and phase of plastic deformation. Paracetamolum was studied in the five mixtures, where it occurred in different ratio with microcrystalline cellulose. Looseness, Carr's index and Hausner ratio were evaluated for each mixture. The sizes of reductions ai, sizes of energies Ei and Ri, "half-pressures" pHi and the velocity constants 1/ti were calculated using three-exponential equation of compression for the individual phases of pressing. The results showed poor flow properties of tableting mixtures and thus its unsuitability for direct compression. The results of the study have revealed that increasing amounts of paracetamolum in the mixture increase reduction of volume a1 and velocity of volume change 1/t1 in dependence on the amount of the extruded air and decrease the required energy due to the smooth surface and less friction during the precompression phase. Reduction of volume a2 decrease with the increase of content of paracetamol due to...

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Knapek, Michal. "Studium kooperativních dislokačních jevů v pevných látkách metodou akustické emise." Doctoral thesis, 2016. http://www.nusl.cz/ntk/nusl-353400.

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Title: Study of cooperative dislocation phenomena in solids by the acoustic emis- sion technique Author: Michal KNAPEK Department: Department of Physics of Materials Supervisor: doc. RNDr. František Chmelík, CSc., Department of Physics of Materials Abstract: Plastic deformation of micron-scale crystalline materials differs con- siderably from bulk specimens, as it is characterized by random strain bursts. Three categories of metallic samples were investigated in this thesis: micron- scale copper micropillars with varied geometries, submillimeter-scale aluminum microwires, and aluminum and aluminum-magnesium salt-replicated foams. Very precise fabrication methods and sensitive measurement set-ups consisting of uni- axial compression and tensile tests with concurrent acoustic emission (AE) record- ing were developed. These fine methods allowed for investigations of effects re- lated to plastic deformation at micrometer scales, i.e. the dislocation dynamics associated with the stress drops. Size effects in plastic deformation, as well as clear correlations between the stress drops and the AE events, were found in mi- crosamples, confirming that dislocation avalanches are indeed responsible for the stochastic character of deformation processes also at microscales. Open-cell pure aluminum and aluminum-magnesium...

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33

Šašek, Stanislav. "Studium mikrostruktury a mechanických vlastností jemnozrnných hořčíkových slitin připravených intenzivní plastickou deformací." Master's thesis, 2021. http://www.nusl.cz/ntk/nusl-448480.

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Two magnesium alloys (Mg-4Y-4Gd-2Ca and Mg-2Y-2Gd-1Ca) with high ignition tem- perature were successfully processed by extrusion. Mg-2Y-2Gd-1Ca alloy was addition- ally processed by equal channel angular pressing (ECAP) to achieve ultrafine-grained microstructure. The effect of extrusion parameters on fraction of recrystallized grains, grain size, and texture was revealed by EBSD analysis. The presence of Mg2Ca, REH2 and Mg5RE secondary phases was proven by SEM and TEM. Microstructural condition including distribution and morphology of secondary phase par- ticles directly affected the mechanical properties. Yield tensile stress exceeding 200 MPa was achieved in each condition. Large non-recrystallized grains with strong {10̄10} tex- ture resulted in a significant anisotropy in mechanical properties. Processing by ECAP led to a homogeneous microstructure with a mean grain size below 1 µm. ECAP condition showed superior mechanical properties with a low anisotropy. The developed and analysed microstructural condition resulted in favourable mechanical properties. The studied alloys are therefore promising for the application in aerospace industry. 1

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Barnovská, Zuzana. "Studium mikrostruktury ultrajemnozrnných kovových materiálů metodou pozitronové anihilace." Master's thesis, 2011. http://www.nusl.cz/ntk/nusl-300456.

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In the presented thesis we study the changes in distribution of the size of vacancy clusters in metals processed by severe plastic deformation, so called ul- tra fine grained materials. We use a modern non-destructive method of positron annihilation spectroscopy, which is one of the few methods that allow us to inves- tigate point defects like vacancies with sizes of a few ˚A. The obtained spectra of positrons annihilating in the samples enable us to determine changes of vacancy cluster sizes depending on temperature or severity of the deformation applied on the samples. 1

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35

Škraban, Tomáš. "Mechanické a fyzikální vlastnosti hořčíkových slitin připravených metodou rotačního kování." Master's thesis, 2020. http://www.nusl.cz/ntk/nusl-434492.

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in english For their positive influence on mechanical and physical properties of the material, methods of severe plastic deformation are popular for quite some time today. Rotary swaging is one of them. With its simplicity and productivity, it has the potential for industrial use. It is a radial swaging of rods or tubes, which results in decreasing of their diameter. Influence of this method is researched on extruded rods made of magnesium alloy AZ31. Experiments are made on five samples of different degree of swaging (different diameter). This allows to research gradual evolution of properties during the swaging. Results show significant positive influence on grain size (and microstructure in general) of originally extruded rod. During swaging there is an evolution of material texture and increase in strength.

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36

Le, Thanh Tra. "Hodnocení stresové relaxace směsí laktosy a hydrogenfosforečnanu vápenatého určených k přípravě tablet s theofylinem." Master's thesis, 2016. http://www.nusl.cz/ntk/nusl-344178.

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Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of: Pharmaceutical technology Consultant: Mgr. Petra Svačinová, PhD. Student: Le Thanh Tra Title of Thesis: Evaluation of stress relaxation of mixtures of lactosum and calcii hydrogenphosphate for preparation tablets with theophylline This thesis studies viscoelastic behavior of fillers and tensile strength of tablets with theophylline. Used material are described in theoretical part: Laktosum SpheroLac 100, microcrystalline cellulose Comprecel 102, calcium hydrogenophosphate anhydrate Di-Cafos A150, calcium hydrogenophosphate dihydrate Di-Cafos D160, theophylline and magnesium stearate. Thesis also describes the stress relaxation test, methods of evaluation and it's application. Experimental part evaluates viscoelastic behavior and tensile strength through the test of stress relaxation with maximal compression force 10 kN and dwell time 180 s. The tensile strength of tablets is also evaluated. Experimental part evaluates parameters of elasticity Ai and plasticity Pi, which were obtained from the test of stress relaxation. It evaluates effect of different fillers on these parameters. The highest values were measured at mixtures E (Spherolac 100 a Comprecel 102), further at mixtures D (Spherolac 100 a Di-Cafos A150) and...

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Damborský, Ondřej. "Rovnice sypání granulátu sorbitolu s přídavkem stearanu hořečnatého." Master's thesis, 2016. http://www.nusl.cz/ntk/nusl-344356.

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Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of: Pharmaceutical technology Consultant: Doc. PharmDr. Zdeňka Šklubalová, Ph.D. Student: Ondřej Damborský Title of Thesis: Flow equation of sorbitol granules with addition of magnesium stearate. The aim of this thesis is to study particulate built and consolidation properties of the granulate prepared by wet granulation of sorbitol and it's size fractions in the range of 0,2 - 0,8 mm and it's influence of adding lubricate magnesium stearate 0.5% and 1.0%. The properties were studied by the angle of repose, the three kinds of bulk density, tap density, the Hausner ratio. The granules showed adequate to good flow properties. The addition of magnesium stearate flow increases the rate through the granulate sorbitol. Mass flow rate through the orifice the conical hopper of the test depending on the particle size and hole diameter were monitored. With increasing particle size the rate of pouring decreases, while the diameter of the hole had the opposite effect. Dependence of the flow rate to the average of the opening of the hopper was modeled by a power equation Jones-Pilpel. When using the current parameters with accuracy reverse estimate of the flow rate ranged between approximately 2 - 4%.

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Marcinek, Tomáš. "Vliv rychlosti lisování na průběh lisovacího procesu." Master's thesis, 2016. http://www.nusl.cz/ntk/nusl-345662.

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Charles University in Prague, Faculty of Pharmacy in Hradci Králové Department of Pharmaceutical Technology Consultant: Mgr. Pavel Ondrejček, Ph.D. Student: Tomáš Marcinek Title of Thesis: The influence of the tableting speed on the compaction process The main aim of this thesis was to determine the influence of tableting speed on the compaction process of four substances. The compaction process was evaluated by three- exponential equation. The parameters of this equation describe the individual phases of compression, the precompression phase, the phase of elastic deformation and the phase of plastic deformation. Furthermore, the effect of tableting speed on the compressibility of the material was studied using the force-displacement record. Finally, the influence of tableting speed on tensile strength of the prepared tablets was evaluated. Four materials were used for the evaluation. Microcrystalline cellulose Avicel PH-102 and dicalcium phosphate dihydrate DI-CAFOS were used as model fillers. Theophylline and paracetamol were used as model drugs. The course of the compaction process was evaluated at five compaction speeds. The results of this evaluation revealed different behavior of used materials. Furthermore different influence on the compaction process by changing compaction speed was...

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Marcinková, Nikola. "Vliv velikosti matrice na průběh lisovacího procesu." Master's thesis, 2016. http://www.nusl.cz/ntk/nusl-345683.

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Charles University in Prague, Faculty of Pharmacy in Hradci Králové Department of: Department of Pharmaceutical Technology Consultant: Mgr. Pavel Ondrejček, Ph.D. Student: Nikola Marcinková Title of Thesis: The influence of the die size on the compaction process This diploma thesis is focused on exploration the influence of the die size on the compaction process. That was evaluated by parameters of three-exponential equation. Compressibility was studied by using force-displacement record. In this work was also observed an effect of die size on the tensile strength. In processing the experimental part of this work were used four different model materials. Microcrystalline cellulose and dicalcium phosphate are used as model fillers and theophylline and paracetamol as model active substances. Compaction of these materials was carried out in dies of size 7 mm, 9 mm, 11 mm, 13 mm and 15 mm. The results of the work showed that the die size significantly affects all parameters force-displacement record. With the growing size of the die there was a reduction of energy parameters. Most of the compaction parameters were statistically influenced. Increasing die size caused reducing volume reduction and energy consumption and increased speed of volume reduction at the stage of pre- compression and elastic...

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Berková, Simona. "Hodnocení lisovatelnosti směsí pelet a mikrokrystalické celulosy." Master's thesis, 2016. http://www.nusl.cz/ntk/nusl-347065.

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Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Consultant: Mgr. Pavel Ondrejček, Ph.D. Student: Simona Berková Title of Thesis: The evaluation of compressibility of the mixtures pellets and microcrystalline cellulose This thesis is focused on the evaluation of powdered microcrystalline cellulose, pellets and mixtures thereof. Comprecel 102 was used as powdered microcrystalline cellulose. The used pellets were commercially available pellets Cellets 100 made of microcrystalline cellulose. The flow properties of used materials and their mixtures were evaluated by using the angle of repose, flow through orifice and Hausner ratio methods. Further the compressibility was evaluated using the force-displacement record. For the evaluation of compaction proces the three exponential compaction was used. Finally the radial tablet strength and tablet friability was tested. The results showed, that the flow properties improved with an increasing amount of pellets in mixture. I tis due to higher bulk and tapped density and also narrower particle size distribution, smoother surface and the regular shape of used pellets. The parameters of the force-displacement method showed different compressibility of used tabletting mixtures. The evaluation of...

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Přeučilová, Michaela. "Porovnání viskoelastických vlastností směsí laktosy a různých typů kluzných látek s využitím testu stresové relaxace." Master's thesis, 2016. http://www.nusl.cz/ntk/nusl-347381.

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Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of: Pharmaceutical technology Consultant: Mgr. Petra Svačinová, Ph.D. Student: Michaela Přeučilová Title of Thesis: A comparison of viscoelastic properties of mixtures of lactose and different lubricants using the stress relaxation test This diploma thesis deals with viscoelastic properties of pharmaceutical excipients and tensile strength of tablets made of these excipients. Theoretical part is dedicated to description of lactose and lubricants, further the tablets compressibility and compression energy profile are described. The end of theoretical part deals with the stress relaxation test, with evaluation methods and the stress relaxation test influence on lactose tablets with different types of lubricants as well. The experimental part deals with the evaluation of the viscoelastic properties of two types of lactose and their mixtures with different types of lubricants at concentration of 1%. These characteristics were evaluated by stress relaxation test. All tablets were compressed by compression forces of 13 kN and 15 kN with dwell time 180 seconds. The study was about differences between two types of lactose, effect of lubricants and effect of two different compression forces on parameters of elasticity A1 -A3 and...

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Straková, Markéta. "Vliv délky prodlevy na parametry testu stresové relaxace u laktosy a hydrogenfosforečnanu vápenatého." Master's thesis, 2016. http://www.nusl.cz/ntk/nusl-347570.

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Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of: Pharmaceutical technology Consultant: Mgr. Petra Svačinová, Ph.D. Student: Straková Markéta Title of Thesis: The influence of dwell time on the parameters of the stress relaxation test for lactose and calcium hydrogen phosphate The aim of this thesis is to find out viscoelastic properties of pharmaceutical excipients and to evaluate the tensile strength of tablets made of them. The theoretical part describes used materials, these are lactose, calcium hydrogen phosphate and magnesium stearate. The thesis also deals with the stress relaxation test, its evaluation and usage. Tensile strength, calculation and various factors that affect tensile strength are described in the text. The experimental part deals with viscoelastic properties of used materials and their mixtures with lubricant using the stress relaxation test. Different dwell times (60 s, 120 s, 180 s, 240 s, 300 s, 360 s, 420 s, 480 s, 540 s, 600 s) were used for individual measurements. The relation between elasticity parameters (A1, A2, A3) and plasticity parameters (P1, P2, P3) depending on the dwell time was investigated. As for calcium hydrogen phosphate, the dwell time 180 - 240 seconds was found as the most appropriate. As for lactose, the optimum dwell...

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Trpělková, Žofie. "Studium procesu lisování pelet z mikrokrystalické celulosy." Master's thesis, 2016. http://www.nusl.cz/ntk/nusl-351358.

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Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Consultant: Mgr. Pavel Ondrejček, Ph.D. Student: Žofie Trpělková Title: A study of a compaction process of microcrystalline cellulose pellets This work is aimed at the comparison of two types of microcrystalline cellulose (Comprecel 102 a Avicel PH-200) with two types of pellets made of microcrystalline cellulose (Cellets 100 a Cellets 200). Important properties for the compaction into tablets were analyzed in these materials. The particle size distribution, the content of moisture, the bulk and tapped density, the flowability, the angle of repose and the Hausner ratio were evaluated. Furthermore, the compaction process was described by using the force displacement method and the three-exponential equation. Finally, the radial strength and the friability of tablets prepared by using two different compaction forces were evaluated. The results proved that both types of pellets have much better flow properties than powdered microcrystalline celluloses. This is primarily caused by the narrow particle size distribution, higher bulk and tapped density and the significantly smoother surface of pellets. Better flow properties of the pellets also influenced the parameters of the force-displacement...

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Hamplová, Kateřina. "Vliv délky prodlevy na parametry testu stresové relaxace u mikrokrystalické celulosy a škrobu." Master's thesis, 2016. http://www.nusl.cz/ntk/nusl-351444.

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Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of: Pharmaceutical technology Consultant: Mgr. Svačinová Petra, Ph.D. Student: Hamplová Kateřina Title of Thesis: The influence of the dwell time on the parameters of the stress relaxation test for microcrystalline cellulose and starch. This thesis is focused on the viscoelastic properties of pharmaceutical excipients and the tensile strength of tablets. The theoretical part describes used materials. Microcrystalline cellulose and starch were used as fillers and magnesium stearate at concentration of 1% was used as lubricant. The stress relaxation test and its evaluation and utilization not only in pharmacy is described as well as the tensile strength of tablets. The experimental part deals with the viscoelastic properties of used materials and their mixtures with lubricant. These properties were evaluated using the stress relaxation test. At maximum compression force of 10 kN the length of dwell time was changed (60 s, 120 s, 180 s, 240 s, 300 s, 360 s, 420 s, 480 s, 540 s, 600 s). For derived parameters of elasticity A1-3 and plasticity P1-3 the dependence on the length of dwell time was evaluated. Parameter A1 increases with increasing dwell time for all substances. For parameters A2, A3, the dependence on the dwell...

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Cruz, Mauro Daniel Carvalho. "Efeito das propriedades elasto-plásticas na propagação de fendas por fadiga." Master's thesis, 2018. http://hdl.handle.net/10316/86073.

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Dissertação de Mestrado Integrado em Engenharia Mecânica apresentada à Faculdade de Ciências e Tecnologia
A fadiga é o modo de falha prematura mais severo e comum em componentes mecânicos durante o tempo de serviço. No âmbito da análise de propagação de fendas, é utilizada, recorrentemente, a relação entre a velocidade de propagação de fendas por fadiga e a gama do fator de intensidade de tensões (da⁄dN‒∆K), apesar das limitações reconhecidas no parâmetro ∆K. O comportamento elastoplástico do material é determinante para da⁄dN, porém não tem sido possível desenvolver estudos paramétricos experimentais ou numéricos. Por outro lado, a utilização do CTOD (deslocamento de abertura de extremidade de fenda) plástico, em substituição de ∆K, permite fazer previsões de da⁄dN e assim desenvolver estudos paramétricos centrados nas constantes do material.Na presente dissertação pretendem-se realizar vários estudos de sensibilidade, nomeadamente, estudar o efeito dos parâmetros do material no ratcheting strain cíclico (δε), na gama de deformação plástica cíclica (∆ε_p) e na gama plástica de CTOD (∆CTOD_p). Além disso, pretende-se verificar se existe correlação entre ∆ε_p e δε em provetes não fissurados, e se é possível transpor diretamente as tendências observadas em provetes não fissurados para provetes com fenda. Finalmente, pretende-se estudar a variação de ∆CTOD_p em função de dos vários parâmetros e o efeito dos parâmetros no fenómeno de fecho de fenda.Constatou-se que, para materiais com encruamento cinemático puro, a tensão limite de elasticidade (Y_0) é, em todos os estudos realizados, o parâmetro mais significativo. Para materiais com encruamento isotrópico + cinemático (misto), o parâmetro mais relevante é a tensão de saturação isotrópica (Y_SAT). Existe uma evidente diferença de sensibilidade entre parâmetros, para cada estudo feito. Nalguns casos, a ordem de parâmetros mais significativos, entre estudos diferentes, é a mesma.
Fatigue is the most severe and common type of premature failure in mechanical components at service. For this reason, its study has been developed with great seriousness. In the analysis of crack propagation, the relationship between the fatigue crack propagation velocity and the stress intensity factor range (da⁄dN‒∆K) is recurrently used, despite its known limitations. The elastoplastic behavior of materials is crucial for da⁄dN, yet it hasn’t been possible to develop experimental or numerical parametric studies. On the other hand, using the plastic component of CTOD (Crack Tip Opening Displacement), instead of ∆K, allows making previsions on da⁄dN and making parametric studies about material’s parameters.The main objective of this thesis is to carry out sensitivity studies, namely: to study the effect of the material’s parameters on the cyclic ratcheting strain (δε), on the cyclic plastic deformation range (∆ε_p) and on the plastic range of CTOD (∆CTOD_p). Also, it is intended to verify if there is a correlation between ∆ε_p and δε on non‒fissured materials and if the results of fissured and non-fissured materials are similar. At last, it is intended to study the trend of ∆CTOD_p as a function of the material’s parameters and their effect on crack closure phenomenon.It was found that, for materials with pure cinematic hardening, the most significant parameter is the yield stress (Y_0). For materials with isotropic + kinematic hardening, the most relevant parameter is the isotropic saturation stress (Y_SAT). There is a clear difference of sensitivity between parameters, for each study. In some cases, the most important parameters are the same for different studies.

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Bartha, Kristina. "Fázové transformace v ultra-jemnozrnných slitinách titanu." Doctoral thesis, 2019. http://www.nusl.cz/ntk/nusl-398721.

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Title: Phase transformations in ultra-fine grained titanium alloys Author: Kristína Bartha Department: Department of Physics of Materials Supervisor of the doctoral thesis: PhDr. RNDr. Josef Stráský, Ph.D., Department of Physics of Materials Abstract: Ti15Mo alloy in a metastable β solution treated condition was processed by high pressure torsion (HPT) and equal channel angular pressing (ECAP). The microstructure after HPT is severely deformed and ultra-fine grained, while ECAP deformation results in rather coarse-grained structure with shear bands containing high density of lattice defects. Two types of thermal treatments - isothermal annealing and linear heating - were carried out for the solution treated condition and both deformed materials. Wide spectrum of experimental techniques was employed to elucidate the differences in phase transformations, especially in α phase precipitation, occurring in deformed and non-deformed material upon thermal treatment. It was shown that the α phase precipitation is accelerated in the deformed materials due to a high density of lattice defects, which provide a dense net of preferred sites for nucleation and also fast diffusion paths necessary for accelerated growth. The enhanced precipitation of the α phase in deformed materials also affects the stability of the ω...

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Stráská, Jitka. "Fyzikální vlastnosti jemnozrnných hořčíkových slitin připravených různými technologiemi." Doctoral thesis, 2014. http://www.nusl.cz/ntk/nusl-338107.

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Title: Physical properties of ultrafine-grained magnesium based alloys prepared by various severe plastic deformation techniques Author: Jitka Stráská Department / Institute: Department of Physics of Materials Supervisor of the doctoral thesis: Doc. RNDr. Miloš Janeček, CSc. Abstract: The objective of the doctoral thesis is the complex investigation of ultrafine-grained magnesium alloy AZ31 prepared by two different severe plastic deformation techniques, in particular the hot extrusion followed by equal-channel angular pressing (EX-ECAP) and high pressure torsion (HPT). These severe plastic deformation methods, and as well as many others, are described in detail in the introductory theoretical section. Experimental results are summarized in the following experimental part of the thesis. Mechanical properties, lattice defect structure and especially microstructure were investigated using various experimental techniques. Thermal stability of ultrafine-grained microstructure of AZ31 after EX-ECAP was investigated and the activation energies for grain growth in different temperature ranges were calculated using kinetic equation for grain growth and Arrhenius equation. Results from the dislocation density measurements proved temperature ranges of the recovery and the following grain growth. Results from the...

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Dissertations / Theses on the topic 'Plastiska deformationer'

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