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Projected User Interface - Dungeons & Dragons
Dymáček, Petr ; Kapinus, Michal (referee) ; Najman, Pavel (advisor)
This thesis deals with the using of an interactive table for playing Dungeons & Dragons board game. Application, that was made, is controlled by touch screen and gestures. The gestures are detected from depth data captured by Kinect. The work solves calibrations of input devices and the design of the user interface appropriate for the application.
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Computational Modelling of Welding and Heat Treatment Process of Steel with Application of Elastic-Viscoplastic Material Model
Jarý, Milan ; Daněk, Ladislav (referee) ; Dymáček, Petr (referee) ; Junek, Lubomír (advisor)
This dissertation thesis deals with the improvement of computational approaches for prediction of residual stresses in welded joints of welded structures in order to ensure greater compliance of the calculated results with the real conditions of welding and heat treatment. The improvement of computational approaches is based on application of elastic-viscoplastic material models which are able (compared with elastic-plastic material models) to take into account the viscoplastic processes ongoing during welding and heat treatment. This leads to more accurate calculated results which enter into further assessment of limit states and directly decide on the safety and lifetime of welded structures. Performed computational and experimental works, confronted with results published in the world, confirm the influence and benefit of application of elastic-viscoplastic material models in the frame of welding and heat treatment numerical analyses. Therefore elastic-viscoplastic material model is further applied in solution of practical project solved by IAM Brno. Solution of this project, whose aim is the development of repair of dissimilar metal welds (without post-weld heat treatment) in Dukovany and Temelin nuclear power plants using "Weld overlay method", has confirmed that application of elastic-viscoplastic material model leads to more accurate calculated results. For this reason the elastic-viscoplastic computational approach will be included into all future tasks of IAM Brno.
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Application of small punch test for determination of high temperature materials characteristics
Ječmínka, Marek ; Dobeš, Ferdinand (referee) ; Dymáček, Petr (advisor)
Diploma thesis is focused on mechanical properties testing by small punch test and comparison of these properties with mechanical properties obtained by conventional tensile test. Steels P92 and AISI 316L in a shape of discs were tested. There were determined values of mechanical properties, namely yield stress, and ultimate tensile stress, obtained by the small punch test – constant deflection rate in this thesis. Values of initial stress and residual stress were evaluated from relaxation small punch test. Mechanical properties obtained by small punch test – constant deflection rate, and small punch test – relaxation, respectively, are compared with mechanical properties obtained by conventional tensile test, and relaxation tensile test, respectively. There were proposed own empirical relationships for restatement of mechanical properties obtained by small punch test to mechanical properties obtained by conventional tensile test in the thesis. Relatively small agreement of results obtained by small punch test, and conventional tensile test was demonstrated by a comparison. Application of own empirical relationships resulted in better agreement. Very good agreement of results of small punch test – relaxation, and relaxation tensile test was shown by their comparison.
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Determination of mechanical properties of light alloys and composites by means of Small Punch Testing
Bártková, Denisa ; Langer, J. ; Dymáček, Petr ; Válka, L.
Nowadays, in many testing areas a volume of experimental material is limited (laboratory-scaled volume, semidestructive approach). Therefore many testing techniques on miniature samples were devised. Principle of Small Punch Test (SPT) method is a penetration of small puncher through thin disc placed on a ring until the disc bursts. In dependence on loading mode it can provide information comparable to uniaxial tensile tests (UTT) and/or conventional constant load creep tests. However clarification of relations between SPT and conventional methods is difficult and empirical formulas are non-universal. The aim of this study is to i) evaluate mechanical properties of aluminium and magnesium alloys and its composites by means of SPT, ii) compare SPT results with UTT, iii) validate correlation formulas from literature, iv) propose more advanced approach to define correlation between UTT and SPT. Measurement were carried out at constant deflection rate (SPT-CDR) in two different laboratoires. Results from both laboratories were compared to evaluate the reproducibility of the method. Better results agreement was reached for the ultimate strength measurements. Yield strength results exhibited greater variance. An influence of pre-deformation of the sample on yield strength and deflection at maximum force was also identified. We can conclude, that for quantitative estimation of strength parameters we can use correlation formulas based on materials with similar composition and fracture behaviour.
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Compressive creep testing of MoSi2-SiC nanocomposites
Luptáková, Natália ; Ballóková, B. ; Dymáček, Petr
The aim of this study is to investigate the creep resistance of molybdenum disilicide (MoSi2-SiC) based composites with different types of embedded particles. The materials were prepared via powder metallurgy using high temperature controlled reaction sintering (CRS). The creep experiments were performed in uniaxial compression at constant stress in the temperature range from 1273 K (1000 °C) to 1473 K (1200 °C) for applied stress from 50 to 100 MPa. Creep was tested by stepwise loading: in each step, the load was changed to a new value after steady state creep rate had been established. The applied stress dependences of the creep rate at different temperatures were analyzed in terms of stress exponent (n) and activation energy (Q). Possible rate-controlling mechanisms were suggested.
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Investigation of Mechanical Properties of Fe3Al-Based Alloys with Vanadium and Carbon Additions by Small Punch Test
Dobeš, Ferdinand ; Dymáček, Petr ; Kratochvíl, P. ; Král, R. ; Çelikyürek, I. ; Torun, O.
Additions of carbon and carbide-forming elements can positively influence high temperature mechanical properties of alloys based on Fe3Al intermetallic compound. In the present study, the effect of vanadium and carbon additions on mechanical properties of Fe3Al-type alloy is investigated by a combination of small punch tests and conventional tensile and compressive tests. The constant-deflection mode of the small punch test is used to estimate the properties and their temperature dependence. The yield force and the maximum force are evaluated from the force vs. deflection dependence and compared with the corresponding quantities resulting from conventional tests. The comparison is discussed in terms of equations suggested previously by Mao and Takahashi. Modifications suggested recently by Garcia et al. are taken into account as well. Fractographic observations of ruptured specimens are performed with scanning electron microscope. Temperature dependence of small punch test quantities is related to the microscopic image of the fracture. Equivalent fracture strain is evaluated from both small punch test data and microscopic observation of fractured specimens. The relation between equivalent fracture strain and small punch fracture energy is examined. Fracture toughness is calculated from the equivalent fracture strain. Temperature dependence of calculated fracture toughness supports the conclusion that the ductility of investigated alloys is not deteriorated by the presence of carbides.
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Applicability of small punch test to determine the material mechanical properties at room and high temperatures
Dymáček, Petr ; Ječmínka, M.
The paper is focused on testing of mechanical properties by small punch test (SPT) and comparison of these properties with mechanical properties obtained by conventional tensile tests of steels P92 and AISI 316L. The yield stress and ultimate tensile stress obtained by SPT at constant deflection rate (SPT-CDR) were evaluated. Values of initial stress and residual stress were evaluated from relaxation small punch test (SPT-R). Mechanical properties obtained by SPT-CDR and SPT-R are compared with mechanical properties obtained by conventional tensile test and relaxation tensile test, respectively. Modified empirical relationships for an assessment of tensile test properties from quantities determined by small punch test are proposed. Good agreement of results of SPT-R and relaxation tensile test is shown by their comparison.
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Prediction of static materials properties of P92 steel based on small punch test
Dymáček, Petr ; Ječmínka, M. ; Abendroth, M.
Small punch testing under constant deflection rate of P92 steel at room temperature was performed. The experimental SPT curves were used for prediction of yield and ultimate strength based on empirical formulas published in the literature and also by numerical inverse analysis with help of finite element method. Conventional tensile tests were performed for verification of the data derived from small punch testing. Good agreement was found in the case of ultimate strength. Determination of the yield strength is less accurate mainly due to significantly lower values of force at yield compared to maximum force measured by SPT. Two approaches for evaluation and determination of the force at yield limit in SPT diagram and estimation of the yield strength of the material are described in the article.
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Influence of atmosphere on small punch testing of P91 steel
Dymáček, Petr ; Dobeš, Ferdinand
The small punch testing (SPT) under constant force condition was performed in various atmospheres: air, hydrogen and argon. The material selected for the study was P91 steel and testing temperature 873 K. The effect of atmosphere on the test results such as time to rupture, minimum deflection rate and other parameters was measured and evaluated. The results show that there is not very strong but definite effect of atmosphere on SPT creep rupture time. The longest times to rupture were obtained in hydrogen atmosphere for whole range of tested forces. However the difference between tests in hydrogen and tests in air or in argon diminished with decreasing force and longer time to rupture.
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The Influence of Carbon on Small Punch Testing of Niobium-alloyed Iron Aluminide
Dobeš, Ferdinand ; Dymáček, Petr
Iron-aluminium-based alloys are promising candidates for various applications at high temperatures. Unfortunately, creep resistance of these alloys is relatively low. It could be improved by introducing second-phase particles, e. g., by additions of carbon and carbide forming elements. On the other hand, the presence of carbides can influence ductility of the alloys with enhanced creep resistance. In the present study, the effect of niobium and carbon additions on the ductility of a Fe3Al-type alloy is investigated. The constant-deflection mode of the small punch test is used to compare fracture properties and their temperature dependence in the alloy with different amounts of carbon. It is shown that both the fracture energy and the deflection at maximum load are greater in the alloy with the greater carbon and that the ductility is not reduced by the presence of niobium carbides. The ductile-to-brittle transition temperature closely correlates with the temperature of phase transformation from D03 to B2 lattice. This temperature is greater in the alloy with lower carbon owing to greater amount of niobium solved in Fe3Al lattice. Complicated temperature dependence of the yield force can be ascribed to the flow stress anomaly inherent for this type of intermetallic alloys
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