Rolling Noise Research Articles

Macro-scale approach for rough frictionless multi-indentation on a viscoelastic half-space

Abstract This paper deals with the numerical study of frictionless viscoelastic tyre/road contact. The present macro-scale approach takes into account both the viscoelastic behaviour of the tyre and the roughness of the road surface by solving the contact problem between a rough multi-indentation surface and a viscoelastic half-space. The method relies on the fact that a viscoelastic solution can be instantaneously reduced to an elastic solution. A simplified description of viscoelastic material behaviour by a rheological model is used. In order to evaluate the efficiency of the method, numerical contact forces for a simple surface composed of seven rigid spherical tips are compared to the results of a classical matrix inversion method. The correlation between both methods is good. The same comparison for a small sample of road surface was performed and the global differences on the contact forces are below 5%. It is observed that the multi-asperity method can predict tyre/road contact with a rather good accuracy and with a drastically reduced calculation time in comparison with classical methods. Then numerical evaluation of tyre/road viscoelastic contact forces for different road textures is compared to elastic prints in order to assess the effect of the viscoelasticity. The authors believe that the present approach is useful for applications such as rolling noise and rolling resistance prediction.

Characterisation of tram noise emission and contribution of the noise sources

The recent expansion of French tram networks and the related local residential complaints mean that a better knowledge of the situations leading to negative reactions from the local inhabitants is required. Hence a research project has been conducted to evaluate and describe noise and vibration emission of trams as well as the perception by the local residents. This paper investigates tram noise emission on common straight track sections, involving two vehicle scales. First the acoustic power and the mean vertical directivity of the total tramset is assessed using an arc of microphones. Then the localisation and the analysis of the main noise sources are performed by means of a cross array during the tram pass-by. Two tram types representing two generations of French rolling stock, both running on two sites with distinct track characteristics, have been investigated considering the effect of speed, tram type, and track type on the noise source contributions and spectral features. Most sources are located in the lower part of the trams, mainly related to rolling noise, with a strong dependence on speed and track type. The tram type dependency, although globally of second importance, influences greatly the noise spectral distribution and behaviour. The HVAC was the only roof-mounted source which could be detected; its contribution towards building storeys becomes significant in configurations of low rolling noise. A tram noise emission model based on the various noise sources has been developed.

113 在来鉄道における転動音の寄与度評価(騒音・振動の解析・改善(1))

Rolling noise is generated by the vibration of wheels and rails due to the excitation force, caused by roughness on the surfaces of the wheels and rails. Theoretical models, such as TWINS model, have been widely used to gain better understandings of rolling noise. In this paper, the model is applied to Japanese railways and validated in terms of vibration and noise. Through the validation work, it is shown that the predictions show a close correlation to the measured values. For the noise spectra, the contribution of the rail to rolling noise is found to depend on the type of tracks.

Investigation of Radiation Characteristics of Noise from Rail

The vibration of railcar wheels and rails due to excitation forces creates rolling noise. Microphone array measurements and theoretical models, such as the Track-Wheel Interaction Noise Software (TWINS) have been widely used to increase understanding of rolling noise. However, the array measurements are often inconsistent with the TWINS predictions and give less prominence to the rail than the TWINS models. This paper examines whether the microphone array measurements give a correct estimate of sound power radiated by the rail. Static tests are conducted to investigate the vibratory behavior of the track by using a hammer excitation. The sound radiation from a vibrating rail then is modeled with an array of monopole sources, whose strengths are assigned according to the rail vibration calculated using a Timoshenko beam model for the track. The radiation properties of the rail are examined using a shaker excitation in order to validate the sound radiation model. Simulations are used to identify the extent to which the microphone array could see the rail radiation. Results showed that a horizontal microphone array focused normal to the rail cannot detect a large part of the noise from the rail in high frequency range where free wave propagation occurs in the rail. Results obtained by using microphone arrays do not reflect the radiation characteristics of the noise from a rail. This causes the contribution of the rail component to noise to be underestimated.

E45 車輪と直線レールの接触における転動音と車体の挙動(E4振動・騒音の低減)

E45 車輪と直線レールの接触における転動音と車体の挙動(E4振動・騒音の低減)

Investigation of the dynamic contact filter effect in vertical wheel/rail interaction using a 2D and a 3D non-Hertzian contact model

Rolling noise is excited by the roughness of the wheel/rail running surfaces. The contact patch acts as a filter attenuating the excitation at wavelengths that are short in comparison with its length. Additionally, the excitation depends on the variations in roughness profile height across the width of the contact. While most available wheel/rail interaction models include the contact filter effect by roughness pre-processing, a time-domain model is presented in this paper that includes the contact filter effect dynamically by an appropriate two-dimensional (2D) or three-dimensional (3D) non-Hertzian contact model. The 2D contact model is based on a Winkler bedding, while wheel and rail are locally approximated by elastic half-spaces in the 3D contact model. The wheel/rail interaction model is applied to evaluate the contact filter effect for different sets of roughness data measured in several parallel lines. It is found that the 3D contact model gives, as a general tendency, a contact force level several dB lower than the 2D model. The differences increase with a decrease in correlation between the roughness on parallel lines and vary significantly with the choice of roughness line in the 2D model.

Acceptance criterion for rail roughness level spectrum based on assessment of rolling contact fatigue and rolling noise

▶ A reference short-pitch rail corrugation spectrum has been derived. ▶ Development of acceptance criterion regarding noise emission and RCF risk. ▶ Demonstration on employing the criterion to analyze altered operational conditions. ▶ Significantly improve means of planning preventive actions, e.g. grinding. The influences of train speed and rail roughness level on rolling noise and subsurface initiated rolling contact fatigue (RCF) impact are studied. In particular, the consequences of short-pitch rail corrugation on tangent track with wavelengths in the interval 3–8 cm are simulated using models of dynamic vehicle–track interaction. Based on the calculated results, a criterion in terms of a limit for maximum levels of rail roughness with respect to the current traffic conditions can be determined. Such a criterion may be useful for planning of rail grinding intervals if used together with a system for regular monitoring of rail roughness levels. It is concluded that the importance of controlling rail roughness increases with increasing train speed. Increasing axle loads on freight vehicles from 22.5 tonnes to 30 tonnes leads to a significant increase in RCF impact. In operational practice, this is usually compensated for by introducing more conformal wheel–rail profile combinations. Calculated vertical wheel–rail contact forces and rolling noise levels show good agreement with field measurements.

Effects on short pitch rail corrugation growth of a rail vibration absorber/damper

Rail corrugation growth is related to the wheel–track dynamics and uneven wear on the rail head. The so-called pinned–pinned resonance of track vibration is considered as the cause of short pitch rail corrugation that is associated with railway rolling noise generation. A promising measure for reducing railway rolling noise is by the use of rail vibration absorber/damper. Reduction of 5–6 dB in the rail radiated noise can be achieved using rail vibration absorber/damper. In addition a rail vibration absorber/damper is found to be able to suppress the pinned–pinned resonance, and thus, its use may lead to attenuate formation of short pitch rail corrugation. In this work the effects of rail vibration absorber on short pitch rail corrugation growth are studied by combining the wheel–track-absorber dynamics, rolling contact mechanics and wear. The evolution process of rail corrugation is simulated and the results show that short pitch rail corrugation, whose wavelength is associated with the pinned–pinned resonance, is effectively suppressed by a rail vibration absorber. The use of rail vibration absorber has both immediate and long term effect on the railway rolling noise control, i.e. reducing the rail radiation and attenuating growth of short pitch rail corrugation, respectively.

Statistical classification of road pavements using near field vehicle rolling noise measurements

Low noise surfaces have been increasingly considered as a viable and cost-effective alternative to acoustical barriers. However, road planners and administrators frequently lack information on the correlation between the type of road surface and the resulting noise emission profile. To address this problem, a method to identify and classify different types of road pavements was developed, whereby near field road noise is analyzed using statistical learning methods. The vehicle rolling sound signal near the tires and close to the road surface was acquired by two microphones in a special arrangement which implements the Close-Proximity method. A set of features, characterizing the properties of the road pavement, was extracted from the corresponding sound profiles. A feature selection method was used to automatically select those that are most relevant in predicting the type of pavement, while reducing the computational cost. A set of different types of road pavement segments were tested and the performance of the classifier was evaluated. Results of pavement classification performed during a road journey are presented on a map, together with geographical data. This procedure leads to a considerable improvement in the quality of road pavement noise data, thereby increasing the accuracy of road traffic noise prediction models.

The sonRAIL emission model for railway noise in Switzerland

In this article, the sonRAIL emission model for railway noise in Switzerland is presented. The model allows precise calculation of emission levels taking into account all relevant variables. The emission levels are determined as sound power spectra for five source heights. The rolling noise is calculated using roughness spectra for wheel and rail. Total rolling noise is sub-divided into track superstructure and vehicle components. The influence of different superstructure types is taken into account using transfer functions. The article explains the calculation procedures as well as the measurement procedures used to generate the model. A method of noise monitoring based on indirect roughness measurements is presented for the acquisition of model data.

The directivity of railway noise at different speeds

For a sound source, directivity is an important parameter to specify. This parameter also reflects the physical feature of the sound generation mechanism. In this article, studies on the directivity of railway noise, by measurement and by theoretical investigation, are discussed extensively and systematically. The two most important noise types, i.e. rolling noise and aerodynamic noise, are focused on. A model of perpendicular dipole pair is proposed to interpret the measurement specified directivity characters of wheel/rail radiation. This model naturally explains why a vibrating railway wheel does not present dipole directivity character and why rail radiation is of different vertical and horizontal directivity characters. Moreover pantograph noise is also found to be of perpendicular dipole components. As for aerodynamic noise around bogies, scattering of the air flow is proposed to be the mechanism of the noise generation; this understanding leads to a different directivity description for the noise component. Directivities of other important noise types are discussed as well; their directivities become understood, although lacking of relevant directivity data. In summary, this study provides applicable directivity functions together with a survey of the directivities of all important railway noise types and components. Hopefully, this work will be useful, for railway noise engineering also contribute to understand better railway noise.

A simple approach for determining the preload of a wire race ball bearing

Wire race ball bearings have been widely used in high-tech weapons. The preload of a wire race ball bearing is crucial in engineering applications. In this study, a more effective approach is proposed for exact determination of the wire race ball bearing preload. A new mathematical model of the preload and the starting torque of the wire race ball bearing was built using the theorem of the 3D rolling friction resistance and the non-conforming contact theory. Employing a wire race ball bearing with a 1000 mm diameter used in a specific type of aircraft simulating rotary table, the numerical analysis in MATLAB® showed that the preload magnitude can be controlled in the range of 130–140 μm. As verification, the experimental results were in agreement with the theoretical results, and confirm the feasibility of this method. This new approach is more exact in the preload range of 10–158 μm than that computed by the numerical method reported in our previous work (Shan et al., 2007b). This implies that the present method contributes to more effectively preventing rolling noise, overturning moments and wear of the wire race ball bearing. The current research provides critical technical support for the engineering application of wire race ball bearings with large diameters.

New vehicle noise emission for French traffic noise prediction

Traffic noise prediction models in France are based on vehicle noise emission values defined by the French Guide du Bruit des Transports Terrestres (Noise Guide for Ground Transport – Noise levels prediction). These emission values are suited for models addressing the noise assessments of road infrastructures and the dimensioning of acoustic protections, needing traffic noise estimations in terms of Ł Aeq over a long period of time (an hour or more). The values, obtained from measurements collected in the 70s, are updated in the publication of a new guide (Methodological Guide, Vehicle noise emissions, to be published), which addresses the road surface influence on tyre/road noise. The emission values are now expressed through the contributions of a power unit component, function of traffic speed, traffic flow type and road declivity, and of a rolling noise component, function of traffic speed and road pavement. The paper outlines the procedures followed to determine the components, gives their numerical values, and illustrates some vehicle noise emissions.

Research on Simulation Platform Architecture for Noise Reduction of Electric Locomotive Wheel

Wheel/rail rolling noise is the main source of noise from railway operations, it is at least as important as aerodynamic noise. In this paper, the makeup of unit modules of CAE(Computer Aided Engineering) simulation platform for of railway passenger car and its function frame are given. Based on finite element method, boundary element method, the structural model, interior acoustic cavity and acoustics model of electric locomotive wheel were analyzed by Nastran and Sysnoise software. This paper is imposed sinusoidal excitation on the wheel, and then the laying of the viscoelastic layer and optimization of damping-wheel, obtain the wheel’s structure of the vibration noise radiation.The analysis result shows that the laying of the viscoelastic layer can reduce wheels radiation noise, and the noise can be reduced from 0.27 to 8.62 dB.Practical application indicated this simulation platform can supply effective technology support for the development of product.

The influences on railway rolling noise of a rail vibration absorber and wave reflections due to multiple wheels

A compound track-absorber model is employed to study the effect of multiple wheels and rail vibration absorbers on a rail, one of the main parts that generate rolling noise. Effects are wave reflections induced by multiple wheel—rail interactions and the increase in the decay rate of vibration along the rail by using a rail absorber. The rail vibration and noise radiation owing to a roughness excitation are studied by comparing the results of calculations with and without rail absorbers and multiple wheels in turn (i.e. four situations in all). These results are given in terms of vibration energy and sound power levels, and a comparison is made between tracks in four situations. Theoretical predictions show that multiple wheels and rail absorbers have significant effects on the rail receptance, the wheel—rail interaction force, and the vibration decay rate along the track. In addition, the influence of multiple wheels on the energy and noise is limited, whereas that of the rail absorbers is notable. The rail component of rolling noise can be reduced by 7.3 dB(A) by using the rail absorber. However, multiple wheels have a slight effect on the rail radiation.

Rail and wheel vibration absorber performance testing.

Rail and wheel dynamic vibration absorbers have been proposed as noise reduction measures for rail transit systems in Europe and the United States. These absorbers are essentially tuned spring‐mass systems that add damping to the rail or wheel, and can effectively control wheel squeal. Their noise reduction effectiveness for rolling noise and rail corrugation noise is less clear. The extensive test results of under‐car and wayside noise reductions are presented and discussed for wheel vibration absorbers at the San Francisco Bay Area Rapid Transit (BART) system for operations on resilient direct fixation fasteners. These results are compared with test results obtained under TCRP Project C3 at the Portland Tri‐Met light rail system for both rail and wheel vibration absorbers. The reduction in pinned‐pinned mode rail vibration by application of rail vibration absorbers on ballast‐and‐tie track at Tri‐Met is discussed.

Empirical Rolling Noise Prediction Models Based on Pavement Surface Characteristics

ABSTRACT Tyre/road noise is a complex phenomenon which is function of tyre, surface properties and speed. This study aims to define a rolling noise prediction model for a reference tyre, as a function of speed, on dense asphalt surfaces with medium-low macrotexture levels. The model was defined by relating texture levels of pavement profiles and rolling noise levels recorded at different speeds. The study also defines an extension of the model valuable for semi-porous surfaces, as a function of only surface characteristics. Both of the models serve as a support tool for mix design of low noise asphalt pavement surfaces.

Tribological study of Fe–Cu–Cr–graphite alloy and cast iron railway brake shoes by pin-on-disc technique

A new class of materials is being installed in railway brake blocks to substitute classic cast iron in order to reduce the rolling noise produced by the roughness of the tread-wheel surface. The tribological properties of cast iron and Fe–Cu–Cr–graphite sintered alloy brake shoes were analyzed. Kinetic friction coefficient ( μ) and wear were monitored by means of a pin-on-disc technique. The sintered alloy brake showed an increase in μ at higher braking velocities while the cast iron brake exhibited a decrease in μ. Wear was greater on the sintered alloy, explained by its low shear strength which decreased due to its low thermal conductivity. The roughness produced by the sintered brake shoes in wheel-tread surface was 10 times lower than that produced by cast iron.

Railway Wheel and Rail Roughness Analysis

The paper deals with the railway wheel unroundness (out-of-round) analysis and with the rail head roughness analysis. Roughness of the running surfaces is the predominant source of noise of rail bound transport systems today. Reliable measurements of the roughness of rails and wheels are crucial for noise reduction purposes. In the past, the main purpose of measurements was the understanding of corrugation growth and rolling noise generation. Meanwhile, quantitative descriptions have gained considerable importance.

Reducing the rail component of rolling noise by vibration absorber: theoretical prediction

A compound track—absorber model is employed to study the performance of a rail vibration absorber in reducing the rail component of rolling noise. The rail vibration and radiation due to a roughness excitation are calculated with the use of the absorber. Different types of rail absorber and installation locations are considered in calculations to investigate their influence on the absorber's performance. The theoretical predictions show that the rail-radiated noise can be reduced by about 6—8 dB(A) using the rail absorber for the situation modelled here. The most appropriate installation place for a discrete absorber is at mid-span between sleepers because the vibration response there is large. As the rail vibration amplitude is small at sleepers, they are not the appropriate installation place for a discrete absorber to reduce rail radiation via energy dissipation. It should be noticed that the performance of the rail absorber is predicted under idealized conditions, and the noise reduction that can be achieved using the absorber is dependent on some practical factors, which are not further studied in this work.