Rolling Noise Research Articles

Life cycle analysis of mitigation methodologies for railway rolling noise and groundbourne vibration

Negative outcomes such as noise and vibration generated by railways have become a challenge for both industry and academia in order to guarantee that the railway system can accomplish its purposes and at the same time provide comfort for users and people living in the neighbourhood along the railway corridor. The research interest on this field has been increasing and the advancement in noise and vibration mitigation methodologies can be observed using various engineering techniques that are constantly put into test to solve such effects. In contrast, the life cycle analysis of the mitigation measures has not been thoroughly carried out. There is also a lack of detailed evaluation in the efficiency of various mechanisms for controlling rolling noise and ground-borne vibration. This research is thus focussed on the evaluation of materials used, the total cost associated with the maintenance of such the measures and the carbon footprint left for each type of mechanism. The insight into carbon footprint together with life cycle cost will benefit decision making process for the industry in the selection of optimal and suitable mechanism since the environmental impact is a growing concern around the world.

Experimental Validation Of An Innovative Procedure For The Rolling Noise Correction

Among the wide contest of the train vehicles rolling noise evaluation, the aim of the paper is the development, implementation and experimental testing of a new method for roughness calculation according to FprCEN/TR 16891:2015 and the successive evaluation of the correction parameters of the measured rolling noise due to the presence of not compliant rail roughness. It is, in-fact, a very often operative condition, the execution of rolling noise tests over standard in-operation rails that are characterized by roughness profiles very different from standard one as those prescribed within the ISO 3095 procedure. Very often, this difference lead to the presence of an exceeding noise that needs to be evaluated and revised for a correct definition of the phenomena. Within the paper, the procedure implementation is presented and later on verified in operative experimental contest; forecasted and measured data are compared and successively commented.

On the Rolling Noise Reduction by Using the Rail Damper

On the Rolling Noise Reduction by Using the Rail Damper

Effect of temperature- and frequency-dependent dynamic properties of rail pads on high-speed vehicle–track coupled vibrations

ABSTRACTThe soft under baseplate pad of WJ-8 rail fastener frequently used in China’s high-speed railways was taken as the study subject, and a laboratory test was performed to measure its temperature and frequency-dependent dynamic performance at 0.3 Hz and at −60°C to 20°C with intervals of 2.5°C. Its higher frequency-dependent results at different temperatures were then further predicted based on the time–temperature superposition (TTS) and Williams–Landel–Ferry (WLF) formula. The fractional derivative Kelvin–Voigt (FDKV) model was used to represent the temperature- and frequency-dependent dynamic properties of the tested rail pad. By means of the FDKV model for rail pads and vehicle–track coupled dynamic theory, high-speed vehicle–track coupled vibrations due to temperature- and frequency-dependent dynamic properties of rail pads was investigated. Finally, further combining with the measured frequency-dependent dynamic performance of vehicle’s rubber primary suspension, the high-speed vehicle–track coupled vibration responses were discussed. It is found that the storage stiffness and loss factor of the tested rail pad are sensitive to low temperatures or high frequencies. The proposed FDKV model for the frequency-dependent storage stiffness and loss factors of the tested rail pad can basically meet the fitting precision, especially at ordinary temperatures. The numerical simulation results indicate that the vertical vibration levels of high-speed vehicle–track coupled systems calculated with the FDKV model for rail pads in time domain are higher than those calculated with the ordinary Kelvin–Voigt (KV) model for rail pads. Additionally, the temperature- and frequency-dependent dynamic properties of the tested rail pads would alter the vertical vibration acceleration levels (VALs) of the car body and bogie in 1/3 octave frequencies above 31.5 Hz, especially enlarge the vertical VALs of the wheel set and rail in 1/3 octave frequencies of 31.5–100 Hz and above 315 Hz, which are the dominant frequencies of ground vibration acceleration and rolling noise (or bridge noise) caused by high-speed railways respectively. Since the fractional derivative value of the adopted rubber primary suspension, unlike the tested rail pad, is very close to 1, its frequency-dependent dynamic performance has little effect on high-speed vehicle–track coupled vibration responses.

Life Cycle Cost Evaluation of Noise and Vibration Control Methods at Urban Railway Turnouts

A focus of the railway industry over the past decades has been to research, find and develop methods to mitigate noise and vibration resulting from wheel/rail contact along track infrastructure. This resulted in a wide range of abatement measures that are available for today’s engineers. The suitability of each method must be analysed through budget and timeframe limitations, which includes building, maintenance and inspection costs and time allocation, while also aiming at delivering other benefits, such as environmental impact and durability of infrastructure. There are several situations that need noise and vibration mitigation methods, but each design allocates different priorities on a case-by-case basis. Traditionally, the disturbance caused by railways to the community are generated by wheel/rail contact sound radiation that is expressed in different ways, depending on the movement of the rolling stock and track alignment, such as rolling noise, impact noise and curve noise. More specifically, in special trackworks such as turnouts (or called “switches and crossings”), there are two types of noise that can often be observed: impact noise and screeching noise. With respect to the screeching (or flanging), its mitigation methods are usually associated with curve lubrications. In contrast, the impact noise emerges from the sound made by the rolling stock moving through joints and discontinuities (i.e., gaps), resulting in various noise abatement features to minimise such noise impact. Life cycle analysis is therefore vital for cost efficiency benchmarking of the mitigation methods. The evaluation is based on available data from open literature and the total costs were estimated from valid industry reports to maintain coherency. A 50-year period for a life cycle analysis is chosen for this study. As for the general parameters, an area with a high density of people is considered to estimate the values for a community with very strict limits for noise and vibration.

A nonlinear circular ring model with rotating effects for tire vibrations

Rolling noise contributes significantly to the noise inside cars. This noise comes from the tire/road contact and for low frequencies (0–400Hz), it is mainly transmitted into the cabin through structural vibrations. Thus estimating this noise requires modelling the tire vibrations by taking into account the rotating effects and the contact with rough surfaces. Concerning the model of rolling tire, a formulation of a deformable solid is constructed by using an Arbitrary Lagrangian Eulerian approach. This formulation is applied on a new simplified tire model which is a circular ring including shear stresses and nonlinear effects due to the vehicle load. This model is successfully validated by comparison with FEM results.

Perception of Tyre Noise: Can Tyre Noise be Differentiated and Characterized by the Perception of a Listener Outside the Car?

When constructing a tyre, it is of importance that improvements and planned changes are not only physically measurable, but that they also can be perceived by a listener. Tyre/road noise becomes a more important focus area, especially with the growing market of electric vehicles. In the design of tyre/road sound, there are three main aims: to reduce the overall sound level, to increase pleasantness and to do so still maintaining the carried information about e.g. driving conditions. To be able to do this, an understanding of how physical changes in a tyre are reflected in the perception of the same tyre is essential. In the present study, the aim is thus to determine if the rolling noise of a tyre can be both differentiated and characterized by its perceptual qualities. The focus is on the perception of the sound outside the car, perceived by, for example, a pedestrian. Listeners have judged different road tyre combinations and their perception in terms of their emotional responses (pleasantness, activation and stress) and their psychoacoustic responses (loudnes s, sharpness, roughness, and pitch). The results confirmed that rolling noise can be perceptually differentiated. Further, it is possible to differentiate between the effects of the street and the effects of the tyre on all emotional and most psychoacoustic parameters. The results suggest that changes to both road surfaces and tyres can affect both emotional and psychoacoustic perceptual qualities.

Radiation of rail noise regarding surface impedance of ground by using wavenumber domain finite and boundary element

An important source of noise from railways is rolling noise caused by wheel and rail vibrations induced by acoustic roughness at the wheel-rail contact. In conventional approaches to predicting rail noise, the rail is regarded as placed in a free space so that the reflection from the ground is not included. However, in order to predict rail noise close to the rail, the effect of the ground should be contained in the analysis. In this study the rail noise reflected from the ground is investigated using the wavenumber domain finite element and boundary element methods. First, two rail models, one using rail attached to the rigid ground and one using rail located above rigid ground, are considered and examined to determine the rigid ground effect in terms of the radiation efficiency. From this analysis, it was found that the two models give considerably different results, so that the distance between the rail and the ground is an important factor. Second, an impedance condition was set for the ground and the effect of the ground impedance on the rail noise was evaluated for the two rail models.

Rail roughness and rolling noise in tramways

Companies which manage railway networks have to cope continually with the problem of operating safety and maintenance intervention issues related to rail surface irregularities. A lot of experience has been gained in recent years in railway applications but the case of tramways is quite different; in this field there are no specific criteria to define any intervention on rail surface restoration. This paper shows measurements carried out on some stretches of a tram network with the CAT equipment (Corrugation Analysis Trolley) for the principal purpose of detecting different states of degradation of the rails and identifying a level of deterioration to be associated with the need for maintenance through rail grinding. The measured roughness is used as an input parameter into prediction models for both rolling noise and ground vibration to show the potential effect that high levels of roughness can have in urban environment. Rolling noise predictions are also compared with noise measurements to illustrate the applicability of the modelling approach. Particular attention is given to the way the contact filter needs to be modelled in the specific case of trams that generally operate at low speed. Finally an empirical approach to assess vibration levels in buildings is presented.

Direct determination of dynamic properties of railway tracks for flexural vibrations

Abstract The vertical vibration of rails constrained and supported by fastening systems occurs due to moving dynamic loads induced from rotating train wheels. The dynamic stiffness and damping capability of the railway track on the viscoelastic medium are essential to evaluate their performance on minimizing rail vibration and environmental noise generation. In this study, a new experimental method to measure the viscoelastic properties of the railway track for flexural vibration was proposed using the wave propagation approach. The proposed method was used to analyze the generation and transfer of vertical rail vibration at frequencies of rolling noise generation and to test actual track models. A slab track model and embedded railway tracks were used in the experiments. The rail was excited by a shaker or an impact hammer, and the resulting acceleration responses were measured at two locations. The flexural wave propagation was found to occur only at frequencies higher than the mass-spring resonance frequency of the rails. After obtaining the wavenumber from the transfer function between the measured responses, the frequency-dependent stiffness and loss factor of the track structures were calculated. The viscoelastic properties of different railway tracks of finite length were measured accurately in the laboratory setups. Then, for validation of the proposed method, the field test was performed using the infinitely long embedded tracks used for a tramway. The measured dynamic stiffness from the finite embedded tracks in the laboratory was very similar to the field test results. The proposed method enables direct determination of the dynamic properties and comparison of flexural wave propagation characteristics of different railway tracks.

The effect of temperature on railway rolling noise

The stiffness and damping of railpads in a railway track are affected by changes in the temperature of the surrounding environment. This results in the rolling noise radiated by trains increasing as the temperature increases. This paper quantifies this effect for a ballasted track equipped with natural rubber railpads and also studies the behaviour of a cork-reinforced rubber railpad. By means of measurements in a temperature-controlled environment, it is shown that the shear modulus of the natural rubber increases by a factor of six when the temperature is reduced from 40 ℃ to −20 ℃. The loss factor increases from 0.15 at 40 ℃ to 0.65 at −20 ℃. The shear modulus of the cork-reinforced rubber increases by a factor of 10, and the loss factor shows the typical trend of transition between rubbery and glassy regions. The railpad stiffness estimated from decay rate measurements at different temperatures is shown to follow the same trend. Field measurements of the noise from passing trains are performed for temperatures between 0 ℃ and 35 ℃; they show an increase of about 3–4 dB. Similar results are obtained from predictions of noise using the measured dependence of pad stiffness.

Towards a model for electric vehicle noise emission in the European prediction method CNOSSOS-EU

The CNOSSOS-EU method is recommended in Europe for environmental noise prediction. In regards to road traffic, it includes vehicle noise emission models implicitly referring to internal combustion vehicles. The development of electrically driven vehicles calls for the future consideration of these vehicles in prediction models. On the basis of experimental data, the study reported in this paper proposes a noise emission model for extending CNOSSOS-EU to light electric vehicles. Correction terms to be applied to the propulsion noise component are determined. Investigations on a sample of tyres with good rolling resistance performance, which is a main tyre selection criterion on these vehicles, indicated that no correction is required for the rolling noise component. Differences between the noise emission from conventional vehicles and electric vehicles are discussed for several road surfaces. Owing to the limited vehicle sample as well as transitional statements, this new model for electric vehicles running at constant speed over 20km/h should be considered as a first step towards the definition of this vehicle technology in CNOSSOS-EU.

Development of raw materials for green tire

With the development of automobile industry, the production amount of China tires has been on the top of the world. But there is still a big gap compared with the developed tire manufactures. The market share of high-end tires is almost completely occupied by foreign manufacturers. With the implement of technical regulation for energy-saving and safety tires of Europe and America tire manufacturers and the legislation of tire labelling law, the most important performance of tires such as rolling resistance, wet-skip resistance and noise are strictly rated, which will be labelled on the surface of tire and will be taken as a guide for tire buyer and technical threshold for domestic tire manufacturers for tire export.

Improved railway wheelset–track interaction model in the high-frequency domain

As it is well known, there are various phenomena related to railway train–track interaction, some of them caused by the high frequency dynamics of the system, such as rolling noise when the vehicle runs over the track, as well as squeal noise and short-pitch rail corrugation for curved tracks. Due to these phenomena and some others unsolved so far, a large effort has been made over the last 40 years in order to define suitable models to study the train–track interaction. The introduction of flexibility in wheelset and rail models was required to have a more realistic representation of the wheel–rail interaction effects at high frequencies. In recently published train–track interaction models, the rails are modelled by means of Timoshenko beam elements, valid up to 1.5 kHz for lateral rail vibration and up to 2 kHz for vertical vibration. This confines the frequency range of validity for the complete train–track model to 1.5 kHz.With the purpose of extending the range of validity above 1.5 kHz, a 3D track model based on the Moving Element Method (MEM) is developed in this paper to replace the Timoshenko beam considered in earlier studies, adopting cyclic boundary conditions and Eulerian coordinates. The MEM approach considers a mobile Finite Element (FE) mesh which moves with the vehicle, so the mass of the rail ‘flows’ with the vehicle speed but in the opposite direction through the mesh. Therefore, the MEM permits to fix the contact area in the middle of a finitely long track and to refine the mesh only around the contact area, where the forces and displacements will be more significant. Additionally, a modal approach is adopted in order to reduce the number of degrees of freedom of the rail model. Both strategies lower substantially the computational cost. Simulation results are presented and discussed for different excitation sources including random rail roughness and singularities such as wheel flats. All the simulation cases are carried out for a Timoshenko beam and a 3D MEM track model in order to point out the differences in the contact forces above the range of validity of the Timoshenko beam.

Review study of main sources of noise generation at wheel-rail interaction

Railways are very economical and efficient long-distance transportation systems in many high-density populated countries. However, in terms of environmental safety, different countries announced an increasing traffic noise near residential area. The relative importance of wheel-rail noise to overall train noise plays a crucial role in developing railway transportation. Generally, there are three types of noise at wheel-rail interaction: rolling noise, impact noise, and squeal noise. Rolling noise refers to vertical vibration excitation on straight track due to the undulations of the wheel and rail surfaces. TWINS as the most advanced model up to date can provide total noise prediction within 2 dB compared to full-scale experiments. The impact noise happens when wheel is running on the rail surface discontinuities. Since linear noise generation assumption is employed at contact patch and non-linear contact element is ignored, impact noise due to large roughness are rarely developed and they need to be extended to the reasonable higher frequencies (5 kHz). The squeal noise is usually due to lateral excitation mechanism and always occurs on sharp radius curves. Due to the complexity of wheel-rail noise generation mechanisms, the almost all existing prediction models either have not been validated or they are bounded to predict noise under limited conditions and certain frequency ranges. In this paper, the differences between three main sources of noise generation at wheel-rail interaction will be reviewed.

Correlation between rolling noise generation and rail roughness of tangent tracks and curves in time and frequency domains

Despite considerable advantages of the railway track over other means of transportation, noise pollution is the main adverse consequence of railway transportation. The basic cause of railway noise is rail corrugation. Although characteristics of railway noise have been considerably studied in the literature, rail corrugation effects on rolling noise generation in tangent tracks and the curves have not been sufficiently investigated. This research addresses the limitations of the current understanding of the rolling noise generation by investigating rail corrugation effects on rolling noise in tangent tracks and curves. This research was made based on the results obtained form a thorough field investigation carried out in a railway line which includes tangents tracks and sharp curves. A track geometry recording car was used to measure rail corrugations. For this purpose, an indirect method was developed in this research to obtain rail corrugation patterns from the data recorded by the track recording car. The effectiveness of the new method was shown. The induced noises were recorded using two particular types of microphones and implementing the method suggested by the ISO 3095 Standard. The rolling noise signal was distinguished from the total noise, using Butterworth Band-Pass Filtering. The role of rail corrugations in the rolling noise was discussed. Correlations were made between various types of corrugations and the induced noises. The results were presented and discussed in the spatial and frequency scales. Results obtained have led to new findings in rail corrugation effects on rolling noise generation. This research paves a way toward a better understanding of rolling noise sources and the parameters influencing the noise.

A full-spectrum analysis of high-speed train interior noise under multi-physical-field coupling excitations

High-speed-railway-train interior noise at low, medium, and high frequencies could be simulated by finite element analysis (FEA) or boundary element analysis (BEA), hybrid finite element analysis–statistical energy analysis (FEA–SEA) and statistical energy analysis (SEA), respectively. First, a new method named statistical acoustic energy flow (SAEF) is proposed, which can be applied to the full-spectrum HST interior noise simulation (including low, medium, and high frequencies) with only one model. In an SAEF model, the corresponding multi-physical-field coupling excitations are firstly fully considered and coupled to excite the interior noise. The interior noise attenuated by sound insulation panels of carriage is simulated through modeling the inflow acoustic energy from the exterior excitations into the interior acoustic cavities. Rigid multi-body dynamics, fast multi-pole BEA, and large-eddy simulation with indirect boundary element analysis are first employed to extract the multi-physical-field excitations, which include the wheel–rail interaction forces/secondary suspension forces, the wheel–rail rolling noise, and aerodynamic noise, respectively. All the peak values and their frequency bands of the simulated acoustic excitations are validated with those from the noise source identification test. Besides, the measured equipment noise inside equipment compartment is used as one of the excitation sources which contribute to the interior noise. Second, a full-trimmed FE carriage model is firstly constructed, and the simulated modal shapes and frequencies agree well with the measured ones, which has validated the global FE carriage model as well as the local FE models of the aluminum alloy–trim composite panel. Thus, the sound transmission loss model of any composite panel has indirectly been validated. Finally, the SAEF model of the carriage is constructed based on the accurate FE model and stimulated by the multi-physical-field excitations. The results show that the trend of the simulated 1/3 octave band sound pressure spectrum agrees well with that of the on-site-measured one. The deviation between the simulated and measured overall sound pressure level (SPL) is 2.6dB(A) and well controlled below the engineering tolerance limit, which has validated the SAEF model in the full-spectrum analysis of the high speed train interior noise.

Simulation of Rolling Noise Based on the Mixed Lagrangian–Eulerian Method

ABSTRACT This article presents a new method for predicting rolling noise, which is an increasingly important subject not only for roads but also for the railway transportation industry and has attracted an increasing amount of attention. Unfortunately, there are no effective numerical methods to analyze and predict rolling noise because of the required solution accuracy. For example, tires are often simplified as shells or rings in rolling noise modelling, lacking the pattern information, and leading to low accuracy. The new method presented in this article is based on the mixed Lagrangian–Eulerian method, which can be used to analyze the velocity field, acceleration field, and contact deformation of rolling contact structures with large deformations. First, two kinds of tire meshes are developed: a Lagrangian mesh for the rolling tire and an Eulerian mesh that is fixed in space and that will be used in the noise simulation. A nonrotational acceleration field is constructed by mapping the acceleration of the Lagrangian mesh onto the Eulerian mesh. Then, using that acceleration field as the acoustic source, the rolling noise can be predicted numerically using the boundary element method. Comparison between the test and simulation results shows that this method provides reasonable predications. The case studies demonstrate that the rolling noise of a tire with a block pattern is mostly caused by the impact vibration of the tire pattern. The method provides a powerful tool for investigating rolling noise, especially for patterned tires.

Impact of Potential and Dedicated Tyres of Electric Vehicles on the Tyre-road Noise and Connection to the EU Noise Label

With the advent of electric vehicles and their significant lower propulsion noise emission it is possible to assess the tyre-road noise trough cruise-by measurements with an increased accuracy, even at speeds where a combustion engine propulsion system would usually disturb the measurement results. The European project FOREVER (Future OpeRational impacts of Electric Vehicles on European Roads) funded by CEDR between 2013 and 2014, aimed to provide data and information on the potential future noise impacts of electric vehicles (EVs) and hybrid electric vehicles (HEVs) on national roads, more specifically (i) the noise levels generated by electric/hybrid vehicles, (ii) how these vehicles can be effectively included in noise prediction models, and (iii) the likely noise impacts for residents as the number of electric/hybrid vehicles on national roads increases. Within work package 3 of the project, concerned with the noise emission of tyres used on EVs and HEVs, nine different sets of tyres have been selected and compared by carrying out pass-by measurements based on the standard ISO 11819-1. Special attention has been paid to potential and dedicated tyre sets which meet the demands for low energy consumption and a low rolling resistance to optimize the range of electric vehicles. The results have been analysed in order to reveal differences between single tyre sets and to quantify the influence of the tyres on the tyre-road noise. In a second part of the work, the EU tyre labels have been considered. The tyre labels have been introduced by the European Community for informing and helping consumers to choose products according to energy efficiency, safety in wet braking conditions and exterior rolling noise. Minimum requirements are also set in type-approval legislation. In the FOREVER project the exterior noise labels of the nine selected tyres have been compared with the results of the pass-by noise measurements performed on a common real-life road surface. Discrepancies observed on tyre ranking between both approaches have been discussed. Investigations within the concept of “low-noise tyres” have been put forward accordingly. Finally, outcomes for the modelling of rolling noise from electric vehicles in the European noise assessment method CNOSSOS-EU, which is recommended for strategic noise mapping in Europe, have been given. As a complement to the EV propulsion noise component previously specified in the FOREVER project, it turns out that no correction term is required for EV rolling noise. In this paper, the main content as well as the outcomes of work package 3 of the project FOREVER are presented.

<b>Evaluation Method for Aerodynamic Noise Generated from the Lower Part of Cars in Consideration of the Characteristics of Under-floor Flows on Shinkansen Trains</b>

A method has been developed for predicting the aerodynamic noise from the bogie of a high-speed train using a two-dimensional microphone array in a low-noise wind tunnel. First, the flow velocity in the rail direction was measured in a field test at several points along the sleeper direction under the train car. Second, the flow distribution was reproduced precisely in a low-noise wind tunnel. Third, aerodynamic noise generated by the bogie (qaerodynamic bogie noiseq) was estimated from the noise source distribution measured with a two-dimensional microphone array. Finally, based on the experimental results, the noise generated from the lower part of the car (i.e. the aerodynamic noise estimated through the proposed method and the rolling and machinery noise estimated in a previous study) was compared with field test data measured near the track. The estimated lower part noise levels showed good agreement with those measured in the field test. This suggests that the proposed method is valid for the quantitative estimation of aerodynamic bogie noise. It was also shown that the contribution of the aerodynamic bogie noise is greater than the rolling and machinery noise, especially in the low-frequency region.