Effect of Wheel Load on Wheel Vibration and Sound Radiation

The current researches of wheel vibration and sound radiation mainly focus on the low noise damped wheel. Compared with the traditional research, the relationship between the sound and wheel/rail contact is difficulty and worth studying. However, there are few studies on the effect of wheel load on wheel vibration and sound radiation. In this paper, laboratory test carried out in a semi-anechoic room investigates the effect of wheel load on wheel natural frequencies, damping ratios, wheel vibration and its sound radiation, The laboratory test results show that the vibration of the wheel and total sound radiation decrease significantly with the increase of the wheel load from 0 t to 1 t. The sound energy level of the wheel decreases by 3.7 dB. When the wheel load exceeds 1 t. the attenuation trend of the vibration and sound radiation of the wheel becomes slow. And the increase of the wheel load causes the growth of the wheel natural frequencies and the mode damping ratios. Based on the finite element method （FEM） and boundary element method （BEM）, a rolling noise prediction model is developed to calculate the influence of wheel load on the wheel vibration and sound radiation. In the calculation, the used wheel/rail excitation is the measured wheel/rail roughness. The calculated results show that the sound power level of the wheel decreases by about 0.4 dB when the wheel load increases by 0.5 t. The sound radiation of the wheel decreases slowly with wheel load increase, and this conclusion is verified by the field test. This research systematically studies the cffcct of wheel load on wheel vibration and sound radiation, gives the relationship between the sound and wheel/rail contact and analyzes the reasons, therefore, it provides a reference for further research.

Finite Element Analysis for the Structure Optimization Design of the CPUE Load-Bearing Wheel of Tracked Vehicle

A new kind of material cast polyurethane elastomers (CPUE) is introduced to take the place of rubber on load bearing wheel for the first time. Based on load bearing wheel dimensions, material properties and operating conditions, the structure of wheel flange is optimized by zero order finite element method. A detailed three dimensional finite element model of flange of load bearing wheel is developed and utilized to optimize structure of wheel flange. Its service life, which is affected by flange structure parameter, is analyzed by comparing the optimization results with those of prototype of wheel. The results of optimization are presented and the stress field of load bearing wheel in optimal dimension obtained by using finite element analysis method is demonstrated. The finite element analysis and optimization results show that the CPUE load bearing wheel is feasible and suitable for the tracked vehicle and has a guiding value in practice of the weighting design of the whole tracked vehicle.

Comprehensive Analysis of High Temperature Performance of SBS-modified Asphalt Mixture

Evaluation of high temperature performance of SBS-modified asphalt mixture was presented.Both wheel loaded method and creep method were adopted for two different mixtures and two kinds of specimens with different height,and corresponding indicators were measured.Meanwhile,the correlation between these indicators was thoroughly analyzed and two kinds of mixtures were compared.The experimental results show that there is a good linear relationship between LWT indicators and CT indicators for M-13,while a relatively poor relationship for M-25,especially that between dynamic stiffness and static stiffness and that between dynamic stability and static creep stiffness.Besides,logarithmic relationship between DS and RD has a higher determination coefficient than that for linear relationship.Thus,multi-index evaluation should be taken for synthetically assessing high temperature performance of asphalt mixture.

Influence of local geometric parameters on fatigue performance of orthotropic steel deck

Fatigue has become critical issue for bridge with orthotropic steel deck.Number of stress cycle and equivalent stress amplitude were adopted as two investigated fatigue effects.As presented from fatigue monitoring comparison of two series-lined bridges,three local geometric parameters of steel box girder have significant influence on fatigue performance of two welded joints.They are thickness of longitudinal ribs(Tr),longitudinal spacing of transverse floor plate(Sc)and longitudinal truss(LT).Fatigue analytical models were created for parametric study of fatigue effects under wheel load.Consequently,three local parameters have exhibited insignificant influence on number of stress cycle.Compared with Tr and Sc,configuration of LT has brought about foremost effect on the equivalent stress amplitude.For equivalent stress amplitude of rib-to-deck and rib-to-rib welded joints,the influence regions of LT are respectively longitudinal strap and quadrate with the geometric length of 600 mm.Enough attention ought to be paid for local stiffen structure on fatigue performance of orthotropic steel deck in fatigue design and monitoring.

Evaluation of High-Speed Track Quality Using Dynamic Simulation of Vehicle-Track Interaction

Track quality is a determinant factor for evaluating the overall performance of vehicle track interaction with respect to safety, ride quality and maintenance. Important parameters specifying the general quality of the track include track geometry (undamped) and track stiffness (damped), which can be evaluated by measurements taken along with track sections. A new co-simulation model based on Finite Element Method (FEM) and Multi Body Simulation (MBS) is built for the detailed description of track quality and its contribution to vehicle track interaction without simplifying the track structure as interconnected single elements. The simulation models and tools have been validated with the help of measured track geometry, track stiffness and dynamic wheel rail forces along the track sections of high speed lines. A comparative study between high speed lines using conventional ballasted track and ballastless track showed a significantly better quality in ballastless track sections. The dynamic forces which were determined by simulations and verified by measurements along the ballastless track section were comparatively less than the specified limits by German regulations for ballastless track design. Lower levels of dynamic forces can be utilized for optimization of track design and installation procedures with respect to lower initial costs.