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Topical Problems of Fluid Mechanics 2020
Šimurda, David; Bodnár, T.
2020 - anglický
Proceedings consist of contributions dealing with both research on various problems in fluid mechanics and mathematical or experimental methods utilizable for solution of such problems.
Klíčová slova:
experimental fluid mechanics; mathematical modelling; CFD; turbulence
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Topical Problems of Fluid Mechanics 2020
Proceedings consist of contributions dealing with both research on various problems in fluid mechanics and mathematical or experimental methods utilizable for solution of such problems.
Measurements on TR-W-1 Cascade
Luxa, Martin; Šimurda, David
2020 - anglický
The research report contains experimetal data from optical and pneumatic measurements on transonic profile cascade with linear part of suction side downstream the sonic line, which is intended for the rotor wheal of a last stage of steam turbine
Klíčová slova:
transonic flow; steam turbine; profile cascade
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Measurements on TR-W-1 Cascade
The research report contains experimetal data from optical and pneumatic measurements on transonic profile cascade with linear part of suction side downstream the sonic line, which is intended for the ...
Measurements on TR-W-2 Cascade
Luxa, Martin; Šimurda, David
2020 - anglický
The research report contains experimetal data from optical and pneumatic measurements on transonic profile cascade with non-linear part of suction side downstream the sonic line, which is intended for the rotor wheal of a last stage of steam turbine.
Klíčová slova:
transonic flow; steam turbine; profile cascade
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Measurements on TR-W-2 Cascade
The research report contains experimetal data from optical and pneumatic measurements on transonic profile cascade with non-linear part of suction side downstream the sonic line, which is intended for ...
Inverse mass matrix for higher-order finite element method in linear free-vibration problems
Kolman, Radek; González, J.G.; Cimrman, Robert; Kopačka, Ján; Cho, S.S.; Park, B.G.
2020 - anglický
In the paper, we present adirect inverse mass matrix in the higher-orderfinite element method forsolid mechanics. The direct inverse mass matrix is sparse, has the same structure as the consistent mass matrixand preserves the total mass. The core of derivation of the semi-discrete mixed form is based on the Hamilton’s principle of leastaction. The cardinal issue is finding the relationship between discretized velocities and discretized linear momentum. Finally, the simple formula for the direct inversemass matrix is presented as well as thechoice of density-weighted dual shape functions for linear momentum with respect to the displacement shape functionwith achoice of the lumping mass method for obtaining the correct and positive definitive velocity-linear momentum operator. The application of Dirichlet boundaryconditions into the direct inversemass matrix forafloating system is achieved usingthe projection operator. The suggested methodology is tested on a free-vibration problem of heterogeneous bar for different ordersof shape functions.
Klíčová slova:
higher-order finite element method; direct inverse mass matrix; consistent and lumped massmatrix; free vibration problem; heterogeneous bar
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Inverse mass matrix for higher-order finite element method in linear free-vibration problems
In the paper, we present adirect inverse mass matrix in the higher-orderfinite element method forsolid mechanics. The direct inverse mass matrix is sparse, has the same structure as the ...
Anomalies detection in time-series data for the internal diagnostics of autonomous mobile robot
Věchet, Stanislav; Krejsa, Jiří; Chen, K.S.
2020 - anglický
Autonomous mobile robots are complex mechatronic machines which consists of numerous hardware and software modules working asynchronously to achieve desired behaviour. As there are many frameworks which helps to overcome the flat learning curve the problem of internal diagnostics arises. While users and developers are able to focus only on solving the high level problem algorithm or methods the internal states of the system is hidden. This helps to separate the users from solving hardware issues, which is helping until everything works properly. We present an algorithm which is able to detect anomalies in time based behaviour of the robot to improve the users confidence that the internal robot framework works correctly and as desired. The algorithm is based on probabilistic patterns detection based on Bayesian probabilistic theory.
Klíčová slova:
anomalies detection; system diagnostic; robot operating system
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Anomalies detection in time-series data for the internal diagnostics of autonomous mobile robot
Autonomous mobile robots are complex mechatronic machines which consists of numerous hardware and software modules working asynchronously to achieve desired behaviour. As there are many frameworks ...
Stress and Deformation of the Filter Press
Fuis, Vladimír; Kašuba, D.
2020 - anglický
The paper presents the stress and deformation analyses of the new design of the filter press made by Envites spol. s r. o. The analyses are solved in system ANSYS and there are nonlinear - due to the modelling by the contact elements and due to the material nonlinearities.
Klíčová slova:
filter press; envites; finite element method; large deformation
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Stress and Deformation of the Filter Press
The paper presents the stress and deformation analyses of the new design of the filter press made by Envites spol. s r. o. The analyses are solved in system ANSYS and there are nonlinear - due to the ...
Measurements on KR-D-3 Blade Cascade
Šimurda, David; Hála, Jindřich; Radnic, Tomáš
2020 - anglický
This report contains result and evaluation of aerodynamic measurements conducted on a subsonic compressor blade cascade.
Klíčová slova:
compressor blade cascade; experiment; subsonic flow; transonic flow; AVDR
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Measurements on KR-D-3 Blade Cascade
This report contains result and evaluation of aerodynamic measurements conducted on a subsonic compressor blade cascade.
An experimental investigation of yield surfaces anisotropies
Štefan, Jan; Parma, Slavomír; Marek, René; Plešek, Jiří; Feigenbaum, H. P.; Ciocanel, C.
2020 - anglický
This contribution is dedicated to a rigorous experimental procedure for evaluation of yield surfaces of common metallic materials. This yield surface tracing procedure employs thin-walled tubular specimens to identify individual yield points of the material under arbitrary combinations of axial load and torque. A yield point is identified on the basis of a prescribed threshold for the effective plastic strain that is being continuously and fully automatically evaluated throughout the test. The experimental results generated with this tracing method are promising, leading to shapes of the yield surfaces conform with the von Mises criterion. The proposed methodology can effectively capture the YS shape.
Klíčová slova:
experimental mechanics; yield surface; directional distortional hardening; metallic materials
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
An experimental investigation of yield surfaces anisotropies
This contribution is dedicated to a rigorous experimental procedure for evaluation of yield surfaces of common metallic materials. This yield surface tracing procedure employs thin-walled tubular ...
Influencing the Indentation Curves by the Bluntness of the Berkovich Indenter at the Fem Modelling
Kovář, J.; Fuis, Vladimír; Tomaštík, Jan
2020 - anglický
The influence of the Berkovich indenter bluntness on the indentation curves at nanoindentation test of fused silica is determined by the FEM (finite element method) in this paper. The Berkovich indenter, which is mostly used for the nanoindentation test, was assumed for calculations. The indenter is always blunted in real tests. The bluntness of the indenter has an influence on the results of the nanoindentation test. The combination of the nanoindentation test and the FE modelling can be used for the calculation of the parameters of fused silica plasticity and estimation of the bluntness of the indenter. In this paper, the FEM was used for calculating of the indentation curves. Two cases of bluntness were assumed. The curves for ideally sharp or blunted indenter were determined. The results of these calculations showed that the indentation curves are dependent on the bluntness of the Berkovich indenter. The greatest relative influence of the nanoindentation curves by the bluntness is in the area of small values of the indenter displacement. The impact of assuming blunted indenter to calculated parameters of plasticity was assessed. It is often difficult to measure the bluntness of the indenter but it has an influence on the results of the nanoindentation test and should be included into calculations to make it more precise.
Klíčová slova:
Berkovich indenter; bluntness; finite element method; nanoindentation
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Influencing the Indentation Curves by the Bluntness of the Berkovich Indenter at the Fem Modelling
The influence of the Berkovich indenter bluntness on the indentation curves at nanoindentation test of fused silica is determined by the FEM (finite element method) in this paper. The Berkovich ...
Influence of contact region size between damping wire andand metal ring on overall damping
Šnábl, Pavel; Pešek, Luděk; Bula, Vítězslav; Cibulka, Jan
2020 - anglický
Damping wire curved to circular shape is inserted into a groove of slightly smaller diameter in damped steel ring. Deformation of circular-shaped wire causes uneven distribution of pressure in the groove and evenno contact between the wire and the groove in some regions. Experimentaimed for nding those regions was performed and the results are shown.Axial pre-stress of the wire was then applied and it was proven that it helps to reduce the regions with no contact. Dynamic test were made to see how larger contact region achieved by axial pre-stress inuences overall damping of damped steel ring.
Klíčová slova:
damping wire; vibration reduction; dynamic test
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Influence of contact region size between damping wire andand metal ring on overall damping
Damping wire curved to circular shape is inserted into a groove of slightly smaller diameter in damped steel ring. Deformation of circular-shaped wire causes uneven distribution of pressure in the ...
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