| 1. |
|
|
| 2. |
- Chaar, Nizar, et al.
(author)
-
Experimental and numerical modal analyses of a loco wheelset
- 2004
-
In: Vehicle System Dynamics. - 0042-3114 .- 1744-5159. ; 41:Suppl., s. 597-606
-
Journal article (peer-reviewed)abstract
- Wheelset structural flexibility is believed to have a major influence on the vehicle-track dynamics. Several studies have related the structural flexibility of the wheelset to fluctuations of wheel-rail forces, rail and wheel corrugation, etc. This paper reports part of an ongoing project that studies the effects of wheelset structural flexibility on the vehicle-track dynamics. The paper focuses on experimental and numerical modal analyses of a loco wheelset in the frequency range of 0-500 Hz. Major issues related to modal analyses and modelling of wheelset are presented along with respective results. The results from numerical modal analysis were in good agreement with those obtained from the experiment. In addition, the wheelset had fairly low eigenfrequencies. Reduced versions of the generated wheelset model will be used in coming work in on-track numerical simulations in order to determine the effects of wheelset structural flexibility on the vehicle-track dynamics. Results from these simulations will be validated against existing experimental on-track results.
|
|
| 3. |
- Chaar, Nizar, et al.
(author)
-
Simulation of vehicle-track interaction with flexible wheelsets, moving track models and field tests
- 2006
-
In: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 44:Suppl., s. 921-931
-
Journal article (peer-reviewed)abstract
- Vehicle-track dynamic interaction emerged as a key multi-aspect subject following the development in high-speed and high axle-load trains. In this context. wheelset structural flexibility and track flexibility are the two main factors that contribute to high frequency content of the wheel-rail forces and influence the vehicle-track damage. Appropriate wheelset and track flexibility models are hence of great importance in pertinent numerical simulations. The present study comprises vehicle-track dynamic simulations considering wheelset structural flexibility and advanced moving track models. Simulated wheel-rail forces are then validated against measured data. The effects of the wheelset structural flexibility and track flexibility on the wheel-rail forces are investigated in the frequency range 0-150 Hz. The influence of track modelling and pertinent data on the simulation results is particularly assessed through a set of moving track models. Measured track data, i.e. irregularities, roughness and flexibility support the simulations. It is confirmed that track flexibility with appropriate modelling and data is important when examining the vehicle-track interaction. In the present case study, the influence of wheelset structural flexibility on the lateral wheel-rail forces is quite significant too.
|
|
| 4. |
- Chaar, Nizar, et al.
(author)
-
Vehicle-track dynamic simulations of a locomotive considering wheelset structural flexibility and comparison with measurements
- 2005
-
In: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit. - 0954-4097. ; 219:4, s. 225-238
-
Journal article (peer-reviewed)abstract
- Wheelset structural flexibility, that is the elastic deformation of the wheelset as a structure, can significantly influence the vehicle-track dynamic interaction. In this paper on-track simulations considering flexible wheelsets, modelled through eigenmodes derived from a finite element model, are presented and compared with on-track measurements. The effects of the wheelset structural flexibility on track forces, in the frequency range 0-100 Hz, are investigated. Results from parametric studies are also presented. The present application is a Swedish Rc7 locomotive having rather slender wheelsets. It is shown that both lateral and vertical track forces are significantly influenced by the wheelset flexibility and that the agreement with measurements is fairly good. The wheelset flexibility increases the lateral track forces. The track representation in the present context is important and the used so-called moving track model needs improvements.
|
|
| 5. |
- Chaar, Nizar, 1970-
(author)
-
Wheelset Structural Flexibility and Track Flexibility in Vehicle-Track Dynamic Interaction
- 2007
-
Doctoral thesis (other academic/artistic)abstract
- This thesis investigates the influence of wheelset structural flexibility and track flexibility on the vehicle-track dynamic interaction, mainly in terms of wheel-rail forces up to 200 Hz, using simulations and measurements. The previous knowledge in this field is first reviewed and summarized, then two case studies are selected for investigation. The first case study involves a locomotive running on a tangent track section at a speed of 140 km/h, while the second one deals with a newly designed motor coach running at two adjacent and tangent track sections with different track components and at speeds up to 280 km/h. For the locomotive case study, the wheelset dynamic properties are first investigated through experimental modal analysis (EMA) for a frequency range of 0-500 Hz, assuming free boundary conditions. The EMA results showed relatively low wheelset eigenfrequencies. A three-dimensional finite element (FE) model, which also includes the wheelset gear-box, is then developed and validated against the measurements for frequencies up to 200 Hz with good agreement. The FE results displayed a significant influence of the wheels’ flexibility on the wheelset’s total structural flexibility. In order to assure proper representation of the track flexibility the vertical and lateral dynamic track properties at a sleeper are measured through a special vehicle at standstill, and measured track irregularities are used. In the numerical simulations, the wheelset structural flexibility is introduced using the calculated eigenmodes above while so-called moving track models are used to model the track flexibility. The simulated wheel-rail forces are then validated against measured ones obtained from corresponding on-track measurements. Results from the simulations highlight the importance of proper track flexibility modelling and track data and also show a significant influence of the wheelset structural flexibility on the lateral track forces. For the motor coach case study, the wheelset dynamic properties are determined through numerical modal analysis using a rather simple FE model and a number of eigenmodes are then introduced in the simulations. The vertical and lateral track dynamic properties at selected track sections are measured using the standstill technique but rolling stiffness measurements, where the vertical track flexibility in the frequency range 5-50 Hz is measured continuously along the track, are also included. The track flexibility is introduced through moving track models. Measured track irregularity and vertical track roughness are also considered. Basic numerical simulations, where the calculated track forces are compared to measured ones, are first performed and followed by a set of parametric studies. The results display a significant influence of the track flexibility on vertical wheel-rail forces for frequencies above 80 Hz, with higher forces for the stiffer track (but weaker rails). The effect of wheelset structural flexibility on the lateral force is also confirmed. The parametric studies highlight the importance of track flexibility modelling and show that modifications of the vertical track receptance, motivated by uncertainties in the pertinent measurements, can improve the simulated forces.
|
|
| 6. |
|
|
