On Dynamics of Radial Elastic Wheelsets

Transcription

1 VSDIA 2000, 7 th Mini Conference, Budapest, 6 8 November On Dynamics of Radial Elastic Wheelsets H. Claus Contents: Motivation Model Development and Simulation Results Parameter Optimization Additional Investigations Conclusion

2 Motivation DFG Project: Radial elastic Wheelsets ICE: Brumming noise and polygonalized wheels Conventional wheels Remedy: Rubber suspended wheels Since the Eschede accident: Return to conventional wheelsets accepting their disadvantages Radial elastic wheels Rubber Investigation: Optimization of stiffness and damping parameters for other designs of radial elastic wheels?

3 Stochastic Excitation Vehicle excitation One sided spectral density in space domain Vertical excitation Spectral Representation Sample function of geometrical track irregularities Track irregularities Vehicle excitation at v=250 km/h

4 Deterministic Excitation Radius of running surface wears in service polygonalization of n th order: n periodic alteration of radius For excitation frequencies between 70 and 100 Hz: 4. order polygonalization ( km/h) 3. order polygonalization ( km/h) Linear model: excitation frequency = vibration frequency 1. and 2. order polygonalization 5. order polygonalization and higher tie excitation

5 Vibrations of Carbody Measurement: Fulda Würzburg, 260 km/h tie excitation frequency Radial irregularities of running surface 1. order 3. order 2. order 4. order polygonalized wheels 5. order Track irregularities Vertical excitation of the passenger coach Evaluation of traveling comfort Black Box sound power level Assumptions: polygonalization, track irregularities mean square value (Gaussian process)

6 Model 1 Source model (Jaschinski 1992) Elastostatic secondary suspension (massless elements) carbody Elastodynamic secondary suspension Investigation of the frequency response of the secondary spring bogie frame wheelset Track and ballast suspended Static and dynamic secondary suspension are modular interchangeable in the model track body subsoil Eigen frequencies of the secondary spring:

7 Simulation Results (Model 1) Spectral density of vertical acceleration White noise and realistic track irregularities are suitable for excitation Model1 does not describe the vertical dynamics sufficiently! Secondary suspension Amplitudes strongly sensitive to traveling velocity Amplification of amplitudes only in small ranges of frequency Excitation System response to white noise corresponds to the frequency response response to polygonalized wheels follows the frequency response System response to realistic track irregularities: behavior of a passenger coach running with ideal wheels Strong decrease of acceleration amplitudes in higher frequency range

8 Model 2 and Simulation Results FE Modeling Modal Reduction Multibody System Approach 1/2 bogie frame model First three eigen modes: Spectral density of vertical acceleration Excitation: realistic track irregularities Wide frequency range with increased amplitudes Model 2 shows vertical vibrations which may cause the brumming noise!

9 Model 3 and Simulation Results Radial elastic wheels (MBS Model) wheel disc wheel rim rubber Spectral density of vertical acceleration Excitation: realistic track irregularities Parameter: Radial stiffness of a single wheel: Viscous damping factor: Acceleration amplitudes considerably decreased between 70 and 100 Hz Model 3 shows the positive effect of radial elastic wheels on traveling comfort!

10 Parameter Optimization

11 Parameter Optimization (Cont.) Response to unit step excitation time [s] original value of stiffness of secondary suspension: Roll motion Original stiffness coefficient well chosen! c c c SC SC SC =1e5 N/m =3.5e5 N/m =7e5 N/m

12 Parameter Optimization (Cont.)

13 Experimental Data

14 Conclusion