|
| |
|
| |
|
|
Temperature processes at dry friction
Pešek, Luděk ; Půst, Ladislav ; Cibulka, Jan ; Bula, Vítězslav
Application of dry friction damping contact is very often used for damping of turbine blades vibration. This problem is intensively studied in our Institute for several years, but the deficiency of knowledge of special material’s friction characteristics introduces serious uncertainty into the results of research. Therefore laboratory experimental equipment has been designed and realized. Results of the first set of measurement is presented and discussed. Friction double of steel blade material and overlay of tungsten carbide was investigated at various thrust forces and frequencies of relative motion at the simultaneous measurement of temperatures in tree points near the friction surface. Increase of temperature after 25 s of friction run, friction coefficient, friction force, dissipated energy in one cycle, during 1 s, entire energy during the friction run, lost power, and energy for 1oC temperature increase at various conditions were ascertained.
|
|
|
Tribologické chovaní tvrdých uhlíkových kompozitních vrstev
Fořt, Tomáš ; Grossman, Jan ; Sobota, Jaroslav ; Vítů, T. ; Novák, R.
Carbon hard composite coatings were exposed to dynamical load and high temperature pin-on-disc CSM Tribometer. To evaluate the impact resistance of thin hard composite coating in dynamic loading wear applications an impact test was used. The sliding tests in air were carried out in the range from room temperature to 500 °C with controlled relative humidity. Hardness, elastic modulus and fracture toughness of deposited coatings were studied by indentation technique using Fisherscope H100 tester.
|
|
|
Properties of thermo-visco-elastic material 42-809 for manufacturing of vibrodamping elements – 3.part
Svoboda, Jaroslav ; Pešek, Luděk ; Frölich, V. ; Klášterka, Petr
In the report the results of rubber elements properties made of thermo-visco-elastic material 42-809 at low temperatures are summariesed. The tests were performed by a loading fatigue machine INSTRON 8502 in a climate chamber. For improving an accuracy of measurement the test machine was equipped with a lesser force transduser Rumburk with a range up to 40kN. The report includes results of static and dynamic characteristics in temperature range 0 ÷ -50°C, measurement of residual deformations, relaxation time and evaluation of a cyclic loading influence to shapes of static characteristics of the rubber. Furthermore the results of rubber element life time and evaluation of friction behaviour at lower temperatures are presented. The limit lines for 10% of residual deformations are drawn here, too.
|
|
|
Flow resistance of simple 2D bodies in wide range of Reynolds numbers
Hoření, Bohumír ; Chára, Zdeněk
Paper presents results of numerical simulation of flow resistance of selected 2D bodies (flat plate, cylinder and cylinder of square cross section) with help of program Fluent 6 for Reynolds numbers in the range Re=0.5 - 5000000 and the simulations are compared with available experimental data. The aim of the paper was to determine regions where the numerical calculations could give reasonably results.
|
guest ::
