Corrugation Growth Research Articles

A rail corrugation index to characterize noise impacts and grinding effectiveness on rail transit systems

Despite general agreement that rail corrugation generates unwanted noise, there is a need to quantify the relationship between rail corrugation and noise and to leverage this relationship within preventive rail grinding programs. This paper develops a novel rail corrugation index (RCI) and demonstrates the suitability of that index to characterize the relationship between corrugation and noise, to assess grind effectiveness, and to predict noise as a function of rail corrugation. Using a time-series data set collected at a North American rail transit property, the proposed RCI illustrated corrugation growth as a function of accumulated tonnage and an expected reduction of corrugation after grinding. The RCI also correlated well with corresponding wayside noise observations. The evident response behavior and the relationship between rail corrugation and wayside noise gave rise to the assessment of grind effectiveness using the RCI. Further, a modelling effort demonstrated that noise can be predicted using the RCI calculated from only one rail (left or right) on a tangent section. This result suggests that there may also be an opportunity to predict corrugation using noise data, thus limiting the need for track downtime required to measure corrugation.

<b>Method for Evaluating Rail Corrugation Growth Process by Monitoring Vertical Rail Vibration</b>

<b>Method for Evaluating Rail Corrugation Growth Process by Monitoring Vertical Rail Vibration</b>

Effects of decarburized Layer's material property on the rail corrugation development

A rail corrugation development calculation model that can consider the non-uniformity of material properties near rail surface was established to study the effects of rail decarburized layer on the corrugation growth. Firstly, the elastic modulus and hardness at different vertical positions in the rail decarburized layer were measured using nano-indentation technique. Then a two-dimensional wheel-rail rolling contact theory model that can consider the non-uniformity of material properties was established based on elasticity theory and hierarchical model. A numerical table for fast calculation of wheel-rail contact was established. Finally, the rail corrugation development with the presence of rail decarburized layer was simulated by considering wheel-rail contact with non-uniform material properties in the vehicle-track dynamic simulation. The results show that the decrease of elastic modulus and hardness of rail decarburized layer material would accelerate the development of corrugation. The corrugation growth rate with the presence of rail decarburized layer increases 43%. The maximum peak-to-valley depth of rail corrugation is about 9 times larger on the rail with decarburized layer than that on the rail without decarburized layer. Although the hardness plays a much more significant role in the corrugation development than the elastic modulus, the elastic modulus still has some influence on the growth rate of corrugation depth. The maximum depth of corrugation considering the non-uniformity of both elastic modulus and hardness is 11.7% larger than that considering only the non-uniformity of hardness.

Short-pitch corrugation formation on resilient fastener metro tracks explained using rail-bending vibrations within the bogie wheelbase

Short-pitch corrugation is a serious problem on resilient fastened railway track for many metro lines, causing severe noise and vibration that shortens the life of the vehicle and track components. To address this problem, the formation mechanism of this kind of corrugation is investigated in this study. The corrugation characteristics and natural frequency of the resilient fastener track are determined by field investigations. Then, ‘frequency sweeping’ and long-term rail-roughness prediction models are developed to reveal the crucial role of the interactions between two wheelsets in the corrugation formation and to estimate the effects of speed variations and bogie wheelbase on corrugation growth. The spectral analysis results indicate that the spatial frequency spectrum exhibits several peaks at equal intervals due to the short-pitch corrugation of a resilient fastener metro track, which are related to the third-order rail-bending vibration within the bogie wheelbase at about 775 Hz. In addition, large and small speed variations affect the wavelength and depth growth of the corrugation, respectively. The growth of corrugation depth is amplified when the resonance frequency associated with the corrugation formation is an integer-multiple of the wheel-passing frequency. The wheelbase is also an important factor in determining the corrugation wavelength because of its influence on the resonance frequency.

Predicting rail corrugation in a real line by means of a fast non-linear vertical and lateral model

This work is the result of a problem of premature development of rail corrugation found on a new metro line. As urgent solutions, a rail grinding was carried out and friction modifier started to be applied. Experimental corrugation measurements have been taken periodically in this line at 60 control points since 2018, and an extensive database has been collected since then. As a second stage, a computationally efficient new model has been developed to predict corrugation growth under different running conditions. The aim of this work has been to obtain feasible solutions to delay corrugation growth in metro type lines.

Mechanism of short pitch rail corrugation: initial excitation and frequency selection for consistent initiation and growth

ABSTRACT This paper proposes a new hypothesis for the formation process of short pitch rail corrugation. An FE wheel-track dynamic model is utilized to verify the hypothesis by reproducing corrugation initiation and consistent growth. It is found longitudinal compression modes are responsible for corrugation initiation with necessary initial excitation that allows flexibility for longitudinal vibration. Consistency between longitudinal compression and vertical bending eigenfrequencies of the wheel-track system is required for consistent corrugation growth, which also determines maximum corrugation amplitude. Corrugation initiates by frequency selection instead of wavelength fixing. The proposed mechanism can explain field observations including the wavelength and periodicity of corrugation in the Netherlands, why corrugation forms on continuously-supported tracks where pinned-pinned resonance does not exist, and the small variation between the corrugation wavelength and train speed.

A novel rail corrugation suppressor using synergistic mechanism of vibration absorption and damping

Rail corrugation increases the intensity of interaction between the wheel and the rail, make the vehicle and track vibrate more strongly, and increase the rolling noise. Based on the fixed corrugation wavelength mechanism, this paper determines the required corrugation wavelength to be controlled using field investigations. A new type of corrugation suppressor is developed that combines a dynamic vibration absorber and a labyrinth damper. The purpose of the suppressor is to realize wide-band vibration resistance and energy consumption, and to control the vibrations in a specific frequency band. By analyzing the vibration transmission characteristics of a typical small-radius curved subway track, it is verified that the device can flatten the rail dynamic response function, suppress the pinned-pinned resonance of rail, and increase the transmission attenuation rate of rail vibrations. A coupled rigid-flexible model of vehicle and curved track is established. The rail vibration and corrugation growth rate before and after installing the suppressor are compared. The suppressor can reduce the 1000 Hz vibrations by 10.1 dB and decrease the medium and high frequency vibrations of the rail by 5.6 dB. At the same time, it can attenuate the rail corrugation growth rate near 500 Hz and between 700-1000 Hz. A field tracking test showed that the suppressor can effectively inhibit the initiation of 15-30 mm wavelength corrugation.

Core formation via filament fragmentation and the impact of ambient pressure on it

ABSTRACT Prestellar cores are generally spheroidal, some of which appear oblate while others appear prolate. Very few of them appear circular in projection. Little, however, is understood about the processes or the physical conditions under which prolate/oblate cores form. We find that an initially subcritical filament experiencing relatively low pressure (≲104 K cm−3) forms prolate cores (i.e. those with axial ratios in excess of unity) via gradual accumulation of gas in density crests. Meanwhile, a filament that is initially transcritical and experiences pressure similar to that in the Solar neighbourhood (between few × 104 and few × 105 K cm−3) forms oblate cores (i.e. those with axial ratios less than unity) via Jeans-like fragmentation. At higher pressure, however, fragments within the filament do not tend to survive as they rebound soon after formation. We also argue that quasi-oscillatory features of velocity gradient observed along the filament axis, and in the direction orthogonal to the axis, are integral to the filament evolution process and arise due to the growth of corrugations on its surface. The axial component of the velocity gradient, in particular, traces the gas flow along the filament length. We therefore posit that it could be used to constrain the filament-formation mechanism. The magnitude of the respective components of velocity gradients increases with increasing external pressure.

Noise Reduction by Rail Damper Tunable for Individual Rails in Curve

Tuned mass rail dampers are cost effective for the mitigation of the airborne noise and vibration with the ability to be tuned for individual site. TMDs have been developed and installed at a single rail in a curve tunnel and achieve more than 4dB(A) noise reduction in many cases. According to the on-site noise reduction performance during damper installation, half, one, two or three dampers can be installed at each spacing between two baseplates. TMDs with only half-installation provides more than 10dB reduction at vertical pin-pin resonance (~1kHz). With the standard installation, they provide the strong damping to half the corrugation growth rate. The stick-slip phenomena which causes the corrugation will be affected by the damping effect from TMDs. On the other hand, they can also be tuned to the low-frequency (p2 resonance) for grandborne noise control. The high reduction of the grand borne noise proved our claim for effectiveness of the TMDs besides many other studies on the other parameters like the type of the baseplates or the soil types. According to the test results TMDs achieve strong performance in different range of the frequencies.

Applying System Dynamics of Discrete Supported Track to Analyze the Rail Corrugation Causation on Curved Urban Railway Tracks

Urban rail corrugation on curved tracks with small radii causes strong howling during operation, which has been bothering subway operating companies for many years. Therefore, revealing its causes and growth is important for the comfort and safety of subway operation. Current studies believe that the occurrence of rail corrugation is largely due to the resonant vibration of the wheel-rail system. However, little attention has been paid to the key causes of the track resonance and the practical prediction of the occurrence probability of rail corrugation on the certain track. This paper intends to solve these above issues. Firstly, the practical model of predicting the rail corrugation growth is proposed based on the wheel-rail coupling interaction, the key causes of corrugation are investigated, and the sensitivity analysis is carried out, while the corrugation superposition model is introduced to the analyze the corrugation evolution as well as to validate the corrugation growth from the aspect of material friction and wear. Secondly, the impact of the key causes on the initiation and development of the rail corrugation is investigated based on the cosimulation. Finally, case studies validate the proposed theory model and method. The results show that the practical prediction model for the rail corrugation growth proposed in this paper is able to estimate the occurrence possibility of rail corrugation on a specific track, and the superharmonic resonance of the track directly excited by passing vehicles eventually leads to rail corrugation. It is also found that shortwave corrugation develops more rapidly, and adjusting the support stiffness or sleeper spacing leads to fluctuations in the corrugation wavelength and its wear rate.

The dynamic resonance under multiple flexible wheelset-rail interactions and its influence on rail corrugation for high-speed railway

The wheel-rail dynamic resonance (W-RDR) under multi wheelset-rail nonlinear interactions in the mid-high frequency range is still unclear regarding wheelset flexibility, wave transmissions and reflections (W-TF) among each wheel-rail interaction. To clearly elucidate W-RDR and its induced modes, a double vehicle-track coupled dynamic model of multiple flexible wheelset-rail interactions is established. The validity of the model in the mid-high frequency range is verified by comparing the simulated axlebox acceleration with the measured data. Then, the W-RDR (vertical force, friction power) is calculated and analyzed. Furthermore, the W-RDR under the single/ double/ multiple wheelset-rail interactions is compared and the rail bending modes between bogie wheels are proposed. The influence of wheelset flexibility and W-TF among each wheel-rail interaction on W-RDR are clarified. Finally, the initiation mechanism of rail corrugation is revealed based on corrugation growth rate. The results show that the wheelset flexibility has limited influence on vertical force resonances but significant contribution to friction power resonances. The W-TF between bogie wheels produce three rail local bending modes. The W-TF between wheels of adjacent bogies further intensify response peaks but do not generate new resonances. The W-RDR is mainly caused by the P2 resonance mode, the rail bending modes between bogie wheels and the wheelset bending modes. The rail 3rd-order bending, pinned-pinned resonance between bogie wheels and the wheelset 2nd antisymmetric bending resonance are key factors in corrugation initiation. Moreover, the wheel-rail resonance at the bogie leading wheelset is more prone to produce corrugation than that at the rear wheelset.

Generation Mechanism and Development Characteristics of Rail Corrugation of Cologne Egg Fastener Track in Metro

By establishing vehicle-track space coupled model and rail corrugation evaluation model, the generation mechanism of rail corrugation was analyzed in frequency domain and time domain, and development characteristics of corrugation were studied by using corrugation growth rate. Analysis based on frequency domain: through modal analysis and frequency response analysis on the finite element model of track structure, it is found that there are natural frequencies of track structure close to measured corrugation passing frequencies. It shows that the vibration modes corresponding to these frequencies can be more easily excited, which can cause the resonance phenomenon of track structure and form the rail corrugation at corresponding frequencies. Analysis based on time domain: the time-history curves of rail vertical vibration acceleration and rail vertical displacement are calculated by using vehicle-track coupled model and the frequency domain transformation of the time-history data is carried out. It is found that there are characteristic frequencies close to the measured corrugation passing frequencies, which indicates that the vibration of track structure at corresponding frequencies is an important reason to promote the formation of corrugation. The change of vehicle speed has no effect on characteristic frequencies of corrugation growth rate curves, which reflects the fixed frequency characteristic of corrugation. With the increase of train operation times, the corrugation corresponding to characteristic frequencies will gradually form and develop, and the increase of vehicle speed will increase the wavelength range and development speed of rail corrugation.

The growth and mitigation of rail corrugation due to vibrational interference between moving wheels and resilient track

ABSTRACT The present work investigates corrugation growth and mitigation associated with vibration interference between multiple moving wheels and resilient track. A discretely supported slab track is developed in the time domain. The tangential contact between the wheel and rail is described using an unsteady two-dimensional model. Combined these two models with long-term wear, the growth processes of corrugation under single and multiple wheel-rail interaction are simulated. The results show that low-frequency standing wave between wheels caused by vibratory interferences can lead to the drastic fluctuation of the contact force and thusly the standing wave-shaped profile of corrugation occur on railhead. It is also found that corrugation with multiple wavelengths successively appear and these wavelengths are always equivalent to unit fractions of the wheelbase, in which characteristic wavelengths predicted reach agreements with the observed results in situ. It is concluded that low-frequency standing wave between moving wheels are the dominant contributions to corrugation growth and the dependence of wavelengths on the wheelbase constitutes the wavelength-fixed nature of rail corrugation. Furthermore, the corrugation mitigation is investigated by installing rail damper. The results show that short pitch rail corrugation can be postponed by rail damper, but rail corrugation have the potential to reappear.

Theoretical investigation into the formation mechanism and mitigation measures of short pitch rail corrugation in resilient tracks of metros

Severe rail corrugation occurs at both the curved and tangent tracks of the metro in Shanghai, where resilient rail fasteners are used to reduce ground-borne vibration by isolating the transmission of track vibration to the infrastructure. The wavelength of corrugation is about 25–30 mm. It could be assumed that this short pitch rail corrugation is caused by the pinned–pinned resonance. However, rail fasteners with low stiffness were believed to be able to suppress the pinned–pinned resonance thereby resulting in corrugation. To investigate the formation mechanism of this specific rail corrugation, a multiple wheel–rail interaction model is used to calculate the wheel–rail dynamic forces caused due to the multiple wheel–rail interactions, which are considered to play a major role in the formation of corrugation. Then the influences on wear and corrugation growth are analyzed in terms of both amplitude and phase of the wheel–rail dynamic forces. By combining the properties of multiple wheel–rail interactions with their influences on wear and corrugation, the growth rates of rail corrugation at different wavelengths (frequencies) are studied to obtain the characteristic wavelength (frequency), at which the highest corrugation growth rate appears. The obtained characteristic wavelength is in good agreement with observation in the practice of Shanghai metro. It is found that the wave reflection from the wheels on the rail is responsible for the short pitch rail corrugation in the resilient tracks. Finally, tuned rail dampers are applied in the multiple wheel–rail interaction models to investigate their effects on rail corrugation growth. The simulation results show that use of tuned rail dampers is effective in suppressing the short pitch rail corrugation occurring at resilient tracks.

An iterative methodology for the prediction of dynamic vehicle–track interaction and long-term periodic rail wear

In this study, a versatile numerical method for the prediction of long-term growth of rail roughness is presented and its functionality is demonstrated for the development of rail corrugation on small radius curves. The procedure includes two sub-modules: (1) a time-domain model for the simulation of dynamic vehicle–track interaction in a wide range of frequencies by using a commercial software for multibody dynamics and (2) a post-calculation of sliding wear based on the Archard’s model in combination with a non-Hertzian and transient wheel–rail contact model. The structural flexibility of the wheelset is accounted for by using the finite element method. The rail wear generated by a large number of passing trains is assessed by recurrently updating the rail surface based on the wear depth calculated in each post-processing step. The current work sets out from a previous study in which a model for the prediction of long-term growth of rail roughness on small radius curves was developed in a general-purpose programming language. By transferring the model into a commercial software, the aim is to develop an engineering tool that is more applicable for different operational conditions, such as various vehicle and track designs and track alignments. The proposed method is verified by comparing the simulation results against those obtained with the pre-existing software. Conditions similar to a 120 m radius curve on the Stockholm metro exposed to corrugation growth on the low rail are considered. The corrugation is found to be generated by the leading wheelsets. The prevailing wavelength-fixing mechanisms are identified and discussed.

Monitoring of Rail Corrugation Growth on Sharp Curves For Track Maintenance Prioritisation

Monitoring of Rail Corrugation Growth on Sharp Curves For Track Maintenance Prioritisation

Reply to Giannakos, K. Comment on: Toughness of Railroad Concrete Crossties with Holes and Web Openings. Infrastructures 2017, 2, 3

This paper responds to the discussion [1] by Dr. K. Giannakos over our technical note [2].[...]

The effect of non-uniform train speed distribution on rail corrugation growth in curves/corners

Rail corrugation is a significant problem in railway engineering, manifesting as an oscillatory wear pattern on the rail head. These profile variations induce unwanted vibrations, excessive noise and other associated problems. Constant train speed for consecutive train passes has been shown to accelerate corrugation growth while widening the probabilistic speed distribution can be shown to mitigate the phenomena. This paper extends this research by investigating the effect of non-uniformity (or asymmetry) in speed distribution on corrugation growth on curved track/corners. To this end, an efficient corrugation growth prediction model is further developed to include quasistatic bogie cornering dynamics and investigated under non-uniform speed distribution conditions. The results indicate that under typical cornering conditions, the rate of corrugation growth is increased (or decreased) when the mean or skewness of the distributed set of passing speeds is biased to higher (or lower) speeds. In particular, for the conditions investigated, controlling (or not controlling) skewness could achieve a further 12% (or −20%) in corrugation growth rate reduction from a nominal 41% reduction due to symmetric speed variation. Hence, non-uniform speed distribution could cause up to a 50% reduction in predicted effectiveness of widened speed distribution control to reduce corrugation growth rate.

Rail corrugation growth accounting for the flexibility and rotation of the wheel set and the non-Hertzian and non-steady-state effects at contact patch

In this work, a simulation tool is developed to analyse the growth of rail corrugation consisting of several models connected in a feedback loop in order to account for both the short-term dynamic vehicle–track interaction and the long-term damage. The time-domain vehicle–track interaction model comprises a flexible rotating wheel set model, a cyclic track model based on a substructuring technique and a non-Hertzian and non-steady-state three-dimensional wheel–rail contact model, based on the variational theory by Kalker. Wear calculation is performed with Archard's wear model by using the contact parameters obtained with the non-Hertzian and non-steady-state three-dimensional contact model. The aim of this paper is to analyse the influence of the excitation of two coinciding resonances of the flexible rotating wheel set on the rail corrugation growth in the frequency range from 20 to 1500 Hz, when contact conditions similar to those that can arise while a wheel set is negotiating a gentle curve are simulated. Numerical results show that rail corrugation grows only on the low rail for two cases in which two different modes of the rotating wheel set coincide in frequency. In the first case, identified by using the Campbell diagram, the excitation of both the backward wheel mode and the forward third bending mode of the wheel set model (B-F modes) promotes the growth of rail corrugation with a wavelength of 110 mm for a vehicle velocity of 142 km/h. In the second case, the excitation of both the backward wheel mode and the backward third bending mode (B-B modes) gives rise to rail corrugation growth at a wavelength of 156 mm when the vehicle velocity is 198 km/h.

Assessment of lubricant applied to wheel/rail interface in curves

Lubrication between wheel and rail in curves is generally known to decrease the friction between wheel and rail, resulting in the reduction of wear of wheel flange and rail gauge corner in high rail, corrugation growth in low rail and noise generation at both of high and low rails. However, the selection of kinds of lubricants and their application methods adopted by railway companies are not necessarily reasonable or effective. This paper describes the results of fundamental studies on the basic characteristics of various lubricants applied to the wheel/rail interface, such as the effect on vehicle traction behavior, spread extent on rail surface, the effect on vehicle/track dynamic behaviors (focused on the lateral force interacting between wheel and rail) and the vehicle braking performance. Finally, a direction for the selection of suitable kinds of lubricants and lubrication methods are proposed according to the results obtained by the above studies.