Aerodynamic Measurements on Transonic Compressor Blade Cascades KR-D-9 and KR-D-10
Šimurda, David; Hála, Jindřich; Luxa, Martin
2023 - English This report contains results and evaluation of aerodynamic measurements conducted on two variant transonic compressor blade cascades with MCA profile (KR-D-10) and DCA profile (KR-D-9) at transonic flow regimes. Keywords: compressor blade cascade; experiment; transonic flow; MCA profile; DCA profile Available at various institutes of the ASCR Aerodynamic Measurements on Transonic Compressor Blade Cascades KR-D-9 and KR-D-10

This report contains results and evaluation of aerodynamic measurements conducted on two variant transonic compressor blade cascades with MCA profile (KR-D-10) and DCA profile (KR-D-9) at transonic ...

Šimurda, David; Hála, Jindřich; Luxa, Martin
Ústav termomechaniky, 2023

Effect of aging on mechanical properties of 3D printed samples using stereolithography
Drechslerová, V.; Falta, J.; Fíla, T.; Dvořák, R.; Kytýř, Daniel
2023 - English This paper focuses on stereolithography (an additive manufacturing technology working on the principle of curing liquid resins layer by layer using ultraviolet radiation) and the effect of aging on the mechanical properties of the material and printed samples. The aging of the material could be a problem for its subsequent use as the stability of the mechanical properties would not be maintained and unwanted deterioration of the material could occur. As part of the research, sets of samples were printed and subjected to different aging methods and subsequently subjected to quasi-static and dynamic uni-axial load tests. From the data obtained, the basic mechanical properties of the material were calculated and compared with each other. The aim of this paper was to investigate whether aging process causes significant changes in the mechanical properties of the materials used, which could have a consequential impact on their use in different industries. Keywords: stereolithography; aging; mechanical properties Available at various institutes of the ASCR Effect of aging on mechanical properties of 3D printed samples using stereolithography

This paper focuses on stereolithography (an additive manufacturing technology working on the principle of curing liquid resins layer by layer using ultraviolet radiation) and the effect of aging on ...

Drechslerová, V.; Falta, J.; Fíla, T.; Dvořák, R.; Kytýř, Daniel
Ústav teoretické a aplikované mechaniky, 2023

Computed tomography system with strict real-time synchronization for in-situ 3D analysis of periodically vibrating objects
Rada, Václav; Fíla, Tomáš; Zlámal, Petr; Koudelka_ml., Petr; Šleichrt, Jan; Macháček, Michael; Vavřík, Daniel; Kytýř, Daniel
2023 - English In the contribution, we present a laboratory system capable of X-ray computed tomography (XCT) scanning of an periodically moving or oscillating object. The system is an in-house developed XCT setup with electromagnetic voice coil actuator mounted on top of the rotary stage of the setup. The strict synchronization of the components, the rotary stage, the electromagnetic actuator movement and the detector readout is accomplished with use of the detector hardware trigger and hard real-time Linux operating system. Cylindrical sample manufactured from epoxy resin with metal particles to enable movement tracking is scanned in a stationary position and during periodical movement induced by the vibration stage. The volumetric data of the scans is compared and the results of this contribution represent an important step towards identification of defects through modal analysis of in-situ harmonically vibrating object. Keywords: computed tomography; hardware trigger; harmonic motion; realtime synchronization Available at various institutes of the ASCR Computed tomography system with strict real-time synchronization for in-situ 3D analysis of periodically vibrating objects

In the contribution, we present a laboratory system capable of X-ray computed tomography (XCT) scanning of an periodically moving or oscillating object. The system is an in-house developed XCT setup ...

Rada, Václav; Fíla, Tomáš; Zlámal, Petr; Koudelka_ml., Petr; Šleichrt, Jan; Macháček, Michael; Vavřík, Daniel; Kytýř, Daniel
Ústav teoretické a aplikované mechaniky, 2023

Analysis suggestion for vehicle scanning method
Bayer, Jan
2023 - English An analytical approach is suggested that can be conveniently applied in the framework of the Vehicle scanning method (VSM). It assumes that the modal parameters of a bridge will be imported from a finite element (FE) program into MATLAB, where the structural response caused by a moving mass and a moving spring mass is solved using coupling equations and numerical integration. A mathematical formulation of the solution is presented together with a short numerical case study that compares the results to a traditional closed form solution. It is shown that when comparing both forms of analysis the suggested approach is more accurate in the case of slow velocities of the passing sprung mass. Other advantages are that the method allows for the mass of the vehicle or (tractor) towing vehicle and a damping \nto be included in the calculation. The user-friendly preprocessing in commercial FE programs can also be considered an advantage. Keywords: moving vehicle; vehicle scanning method; natural frequency; finite element analysis Available at various institutes of the ASCR Analysis suggestion for vehicle scanning method

An analytical approach is suggested that can be conveniently applied in the framework of the Vehicle scanning method (VSM). It assumes that the modal parameters of a bridge will be imported from a ...

Bayer, Jan
Ústav teoretické a aplikované mechaniky, 2023

A short study on self-balancing of vertical rotors mounted in passive contactless bearings
Zapoměl, Jaroslav; Kozánek, Jan
2023 - English Energy losses and wear of the support elements of high-speed rotors can be reduced by mounting the rotors in stable passive contactless bearings, the operation of which is based on magnetic levitation. The goal of the conducted research was to investigate applicability of self­balancing device added to vertical rotors supported by bearings showing low stiffness and damping, which is a specific property of passive magnetic bearings. This paper deals with applicability and efficiency of self-balancing devices added to vertical rotors supported by bearings having very low stiffness and damping, which corresponds to the properties of magnetic frictionless bearings. Keywords: self-balancing of rotors; passive contactless bearings; the influence of external damping Available at various institutes of the ASCR A short study on self-balancing of vertical rotors mounted in passive contactless bearings

Energy losses and wear of the support elements of high-speed rotors can be reduced by mounting the rotors in stable passive contactless bearings, the operation of which is based on magnetic ...

Zapoměl, Jaroslav; Kozánek, Jan
Ústav termomechaniky, 2023

Dynamic tensile experiments of hard rubber on instron test machine under finite deformations
Šulc, Petr; Pešek, Luděk; Bula, Vítězslav; Šnábl, Pavel
2023 - English This paper deals with the first experimental tests of hard rubbers under tensile harmonic loading on the axial-torsional servohydraulic Instron 8852 test machine. The objective of these experiments on cylindrical rubber specimens on this machine is to obtain stress-strain curves of rubber specimens, first considering uniaxial finite longitudinal strains for a single load cycle. Next, the hysteresis loops and their skeleton curves are compared for two selected strain measures as a function of their conjugate stress. It is shown how to obtain the dependence between elongation in the axial direction and constriction in the radial direction, which is used to determine the Cauchy stress in this configuration. Keywords: uniaxial harmonic loading; finite deformation; second Piola-Kirchhoff stress; hysteresis loop; Green-Lagrange strain tensor Available at various institutes of the ASCR Dynamic tensile experiments of hard rubber on instron test machine under finite deformations

This paper deals with the first experimental tests of hard rubbers under tensile harmonic loading on the axial-torsional servohydraulic Instron 8852 test machine. The objective of these experiments on ...

Šulc, Petr; Pešek, Luděk; Bula, Vítězslav; Šnábl, Pavel
Ústav termomechaniky, 2023

Jánovce. Paleomagnetic research. Report
Elbra, Tiiu; Kdýr, Šimon; Uçar, Hakan; Pruner, Petr; Schnabl, Petr
2023 - English Keywords: Jánovce archeological site; Paleomagnetism; Rock magnetism Available at various institutes of the ASCR Jánovce. Paleomagnetic research. Report

Elbra, Tiiu; Kdýr, Šimon; Uçar, Hakan; Pruner, Petr; Schnabl, Petr
Geologický ústav, 2023

Enhanced growth rate of diamond films at low temperature in focused microwave plasma system
Babčenko, Oleg; Bydžovská, Irena; Fait, Jan; Shagieva, Ekaterina; Ondič, Lukáš; Kromka, Alexander
2023 - English The low temperature (< 500 °C) diamond film deposition on fused silica in two different focused microwave plasma systems, i.e. a multimode clamshell cavity (MCC) and a rotational ellipsoid cavity (REC) reactor, was investigated. During the experiments, the methane to hydrogen ratio, in the hydrogen-rich process gas mixture, varied from 1 % to 15 % for MCC and from 1 % to 9 % for REC. The grown films were analyzed by scanning electron microscopy and Raman shift measurements. The outcomes of the study and enhanced diamond growth at low temperatures is advantageous for overcoating of fused silica as well as thermally sensitive substrates, e.g. optical elements, photonic crystals, sensors, etc. Keywords: well-faceted diamonds; low temperature deposition; high growth rate; low non-diamond content; focused plasma Available at various institutes of the ASCR Enhanced growth rate of diamond films at low temperature in focused microwave plasma system

The low temperature (...

Babčenko, Oleg; Bydžovská, Irena; Fait, Jan; Shagieva, Ekaterina; Ondič, Lukáš; Kromka, Alexander
Fyzikální ústav, 2023

Self-balancing of vertical disc rotors supported by contactless bearings
Zapoměl, Jaroslav; Kozánek, Jan; Košina, Jan
2023 - English Article discusses the self-balancing of the vertical disc rotors supported by contactless bearings on principle of diamagnetic levitation. There are three possibilities of contactless supports: permanent magnet levitation with the help of bismuth, graphite and pyrolitic graphite. Keywords: self balancing; vertical disc rotors; contactless bearings Available at various institutes of the ASCR Self-balancing of vertical disc rotors supported by contactless bearings

Article discusses the self-balancing of the vertical disc rotors supported by contactless bearings on principle of diamagnetic levitation. There are three possibilities of contactless supports: ...

Zapoměl, Jaroslav; Kozánek, Jan; Košina, Jan
Ústav termomechaniky, 2023

Topical Problems of Fluid Mechanics 2023
Šimurda, David; Bodnár, T.
2023 - English Proceedings contain collection of papers presented during the conference Topical Problems of Fluid Mechanics 2023. Majority of papers is concerned with numerical simulations covering wide range of applications in fluid mechanics.\n Keywords: experimental fluid mechanics; mathematical modelling; CFD; turbulence; stratified fluid; multiphase flow; vortex structures; supersonic flow Available at various institutes of the ASCR Topical Problems of Fluid Mechanics 2023

Proceedings contain collection of papers presented during the conference Topical Problems of Fluid Mechanics 2023. Majority of papers is concerned with numerical simulations covering wide range of ...

Šimurda, David; Bodnár, T.
Ústav termomechaniky, 2023