11,496 research outputs found
A study of the use of vehicles with small wheels for determining the component of noise from the track
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Extended Validation of a Theoretical Model for Railway Rolling Noise Using Novel Wheel and Track Designs
No full textA theoretical model for railway rolling noise, TWINS, was first developed some years ago and was previously validated against field measurements for conventional wheel and track designs. This model has subsequently been used in the design of noise-reducing wheels and tracks. An outcome of the recent Silent Freight and Silent Track projects was a series of novel designs that were tested in a comprehensive field experiment. Alongside this development, the theoretical model has been updated to improve accuracy and include new features. The results of 34 wheel/track combinations that were measured in field experiments are compared with corresponding predictions using the improved model. It is found that the mean difference between measured and predicted overall A-weighted sound pressure levels is less than 2 dB while the standard deviation is 1.9 dB. The improved accuracy of the model is also shown by a reanalysis of the original validation experiments
A review of the modelling of wheel/rail noise generation
No full textMechanisms associated with the interaction of the wheel and the rail dominate the noise production of railway operations at conventional speeds and remain significant even for high-speed trains. This wheel/rail noise may be divided into three main categories. Rolling noise occurs on straight track and is predominantly caused by undulations of the wheel and rail surfaces which induce a vertical relative vibration. Impact noise can be considered as an extreme form of rolling noise occurring at discontinuities of the wheel or rail surface. The excitation is again vertical, but non-linearities play a greater role. Squeal noise, occurring on sharp radius curves, is usually induced by a lateral excitation mechanism. A review of theoretical models that have been developed to predict these phenomena is given
Sound radiation from a vibrating railway wheel
No full textThe sound radiation characteristics of a railway wheel are investigated by using boundary element calculations. The axisymmetry of the wheel allows an axi-harmonic formulation to be used, in which the wheel is defined by a two-dimensional mesh of its cross-section and the motion is decomposed into harmonics of different numbers of nodal diameters. The radiation ratios of the wheel, vibrating in its various normal modes, are calculated for a range of frequencies. The effects of variation in the wheel radius, web thickness and tyre depth are also investigated. From these results, simple formulae are proposed that allow the radiation ratios to be approximated closely. These are more convenient than the boundary element calculations for calculating the rolling noise from a wheel since they are a function of a few simple geometrical parameters. The directivity of wheel radiation is also considered, with comparisons with measured data indicating that simple monopole and dipole characteristics can be applied
Controlling noise by wheel and track design
No full textRolling noise forms the main source of noise from railways. Effective control at source requires a good understanding of the mechanisms of generation. To this end, detailed theoretical models for rolling noise have been developed. Using these methods, it is possible to evaluate the rolling noise behaviour of different wheel and track designs, allowing new designs to be derived that are inherently quieter. In this paper, an overview is given of the mechanisms involved in noise generation and the parameters that have most influence are identified. Examples are then given of two techniques that have been developed using the model with the aim of reducing the noise at source. A tuned absorber system applied to the rail is found in field measurements to reduce the noise from the track by about 6 dB(A). The wheel component of noise can be reduced by an optimised wheel shape in combination with damping treatments
Extended validation of a theoretical model for railway rolling noise using novel wheel and track designs
No full text
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