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Contribution to Experimental Research of Vibro-Acoustics of Railway wheels with add-on Dampers
Pešek, Luděk ; Vaněk, František ; Veselý, Jan ; Cibulka, Jan ; Boháč, T.
In the contribution a method of measurement and dynamic analysis of the recent operational tests of the monobloc wheel with/without damping elements is presented. On the basis of time-frequency analysis of operational vibration and experimental modal analysis of the wheel its dynamic behavior is described. The vibro-acoustic coupling is analyzed from the comparisons of vibration and sound pressure spectrograms. At passing the curve, the formation and modal-frequency composition of squealing noise is observed and there are identified vibrational modes that mostly contribute to noise emission into surrounding. For quantitative comparison of individual wheel solutions the third octave analysis is used.
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FEM modeling of thermo-mechanical interaction in rubber block
Pešek, Luděk ; Půst, Ladislav ; Šulc, Petr
The FEMLAB code based on weak formulation of PDE’s problem was used at a solution of feedback thermo-mechanical interaction in damping bodies by finite element method. In our approach structural motion and heat conduction equations are solved interactively as time dependent problems. The conservative energy law, i.e. equality of heat energy density and dissipation energy density, realizes the coupling between the equations. The dissipation energy density is computed according to the assumed damping model. In the contribution the results, such as temperature versus strain distribution, of thermo-mechanical processes in case of a plane strain deformation under static compression and cyclic dynamic loading concerning mechanical energy lost modeled as proportional damping, heat generation, heat transfer between rubber and outer steel parts, cooling problem and changing stiffness and damping coef.
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Hyperelesticita pryžového segmentu při jednoosých tlakových zkouškách
Potel, S. ; Pešek, Luděk ; Svoboda, Jaroslav
The plane strain model of hyperelastic material was developed in the ANSYS. For this model, hyperelastic behavior of rubber block and identification of Mooney-Rivlin coefficients from real experimental data for uniaxial compression tests are presented. Furthermore rubber-steel contact problem including tangential Coulomb forces with various friction coefficients were solved. This research is aimed at evaluation of material hyperelastic parameters from static tests and for evaluation of stress state of the rubber segments used as resilient elements in railway wheels. hicle.
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Behavior of thermo-visco-elastic material 42-809 for production of vibrodamping segments - Part I
Svoboda, Jaroslav ; Pešek, Luděk ; Fröhlich, Vladislav ; Vaněk, František ; Klášterka, Petr ; Cibulka, Jan
The report deals with the first results of rubber segment properties for vibrodamping of tram wheels. There are presented static and dynamic characteristics of force and deformation, changes of stiffness, temperature and loss factor with respect to number of cycles. In addition the growth of permanent deformation, lost of recovery, relaxation phenomena etc.
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