Rail Corrugation Growth Research Articles

<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>

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.

Spectral Characteristics of Rail Surface by Measuring the Growth of Rail Corrugation

Continuous interaction between wheels and rails during train operation results in rail wear and tear. Corrugation of the rail surface is particularly caused by the contact mechanism between train wheel and rail and increases the vibration and dynamic wheel load, and if continued, leads to various defects and breakage of the track. Many devices are used to measure corrugation accurately, but measurement deviation varies greatly by measuring device. The most common corrugation measurement system measures surface roughness with a vibration acceleration sensor or displacement sensor. Corrugation with different pitches can be calculated by assuming the longitudinal rail surface as a chord with variable wavelength. Recent systems use a measurement model applying multiple sensors for more accurate measurement. This study investigated spectral characteristics of rail surface roughness based on long time measurement results. In particular, spectral changes upon the growth of rail surface wear and corrugation were analyzed when using the measurement system applying the chord offset method with multiple sensors. The results of analysis were verified through the field subway section, a running track undergoing corrugation, three months after initial measurement, and compared the measurement results according to the number of sensors. Additionally, the rail surface wavelength bands that affected measurement value according to the number of sensors were analyzed.

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.

Modeling the development of rail corrugation to schedule a more economical rail grinding

Rail corrugation should be managed appropriately, as it causes noise, vibration, and degradation of track components and materials. Generally, rail corrugation is managed with the removal of rail surface roughness by rail grinding. However, in many cases, rail corrugation will reoccur after the rail is ground, thereby making the management of the phenomenon difficult for railway operators. For the proper management of rail corrugation, it is necessary to understand the development of rail corrugation and model it mathematically. However, this effort has not been made in previous studies. This paper investigates an efficient method for scheduling a regular grinding maintenance to manage rail corrugation. Using regularly measured data about rail surface roughness on a commercial line, a mathematical model was developed to estimate the growth of rail corrugation. This model was utilized to estimate the effects of the remaining roughness after rail grinding on the maintenance cost and to optimize the maintenance schedule. First, it was confirmed that the development of rail surface roughness of rail corrugation can be expressed in three phases and can be modeled by fitting the functions of growth curves to measurements of rail surface roughness recorded over a long period. Next, the rail grinding strategy was examined by applying this model to realize both effective and economical strategies for the maintenance of rail corrugation. This study confirmed that maintenance costs can be reduced by rail grinding that removes almost all of rail corrugation. In the case of ballasted tracks, it has been found that the optimal grinding schedule can reduce the cost of rail grinding as well as the cost of tamping. These findings can be applied by railway operators tasked with managing maintenance schedules for railway lines at a minimum cost.

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.

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.

“Does god play dice with corrugations?”: Environmental effects on growth

Corrugation growth has perplexed many researchers for several decades with remaining challenges including its reliable prediction in the field. In the present paper, the effect of environmental variations on corrugation growth is investigated using field measurements and mechanics-based modelling. Statistically significant relationships between average daily rainfall, humidity and the growth of rail corrugation were investigated using meterological and railway site field monitoring of a metropolitan network test site with a recurring rail corrugation of about 95mm wavelength. Corrugation growth rate (Gr) was determined by systematically measuring the longitudinal rail profile with a Corrugation Analysis Trolley (CAT) on the 240m radius, narrow gauge, concrete-sleepered curve. Both roughness generated and weld initiated profile growths were investigated. The weather data was obtained from records held by the Bureau of Meteorology. The modelling is developed to provide insight and mechanics based analysis of the field corrugation growth under changes in environmental conditions and vehicle speed variability. Results show a strong correlation between variations in rainfall and corrugation growth that is consistent with changes in steady state wear. Changes in contact patch geometry and the damage mechanism as the corrugation amplitude grows are shown to have substantial but slower effects on growth. The results are used to explain observed changes in corrugation growth rate under variable speed control at the same site.

Rail corrugation growth on small radius curves—Measurements and validation of a numerical prediction model

The development of low rail corrugation (rutting corrugation) on a 120m radius curve on the Stockholm metro is studied by field measurements, laboratory measurements and numerical simulations. The corrugation develops exclusively on the low rail with wavelengths of about 5cm and 8cm. It is concluded by field measurements that the application of friction modification effectively mitigates the corrugation growth on the curve. For the low rail, high levels of lateral acceleration and plastic material flow in the surface layer orientated towards the field side indicate large magnitude lateral creep forces generated by the curving vehicles. A time-domain model for prediction of roughness growth on small radius curves is applied to obtain an improved understanding of the wheel–rail interaction leading to rutting corrugation. The model is validated by comparison of predicted long-term rail roughness growth against measured data, and it is concluded that the corrugation is generated by the low rail contact of the leading wheelset of passing bogies. The corrugation wavelengths observed on the curve are related to excitation of the first symmetric and first antisymmetric bending eigenmodes of the leading wheelsets. Important parameters for the identified wavelength-fixing mechanisms are investigated.

Noise and vibration control by rail dampers

MTR Corporation and Wilson Acoustic Limited launched a project to investigate the effect of rail dampers on noise reduction and rail corrugation growth in an operational metro railway at a 300m radius curved track. Corrugation was measured by Corrugation Analysis Trolley (CAT) every month throughout a 6-month grinding cycle. Corrugation of wavelength 50-80mm was observed at the low rail, corresponding to 250-400Hz at train speed of 70km/hr. No corrugation was observed at the high rail. Corrugation growth rate was reduced by 45% after installation of rail dampers. In contrary to rail corrugation models at tangent track which predict exponential growth with time, corrugation growth at the test site is approximately linear. Corrugation at the test site was thought to be the combined effect of low vertical response and high lateral response at 250–400Hz, resulting in periodic fluctuation of normal contact force, minimal normal contact force is accompanied by lateral sliding causing frictional wear. Rail dampers have no apparent effect on the vertical response at anti-resonance 250–400Hz, but significantly reduce the lateral response. Measurement results and literature reviews suggest that using rail dampers to decrease lateral response could reduce growth of short pitched corrugation at sharp curves.

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.

Investigation of a transitional wear model for wear and wear-type rail corrugation prediction

▶ A calculation procedure for wear coefficient in frictional work wear model. ▶ The application of wear transition model for investigating wear-type rail corrugation growth rate. ▶ Results of the wear coefficient under conditions of friction modifiers and their effects on wear-type rail corrugation; and quantifying of the feasibility of friction modifiers. In this paper, a recently proposed mechanics-based model for the wear coefficient of rail steels is experimentally validated and implemented to obtain useful predictive wear models for some popular railway steels. The model is then implemented to investigate the feasibility of top of rail (TOR) friction modifiers (FMs) for wear-type rail corrugation control. The experimental results confirm the analytical prediction of the first transition (step change in value) of the wear coefficient based on known conditions of creep and load. The implementation of the model under dry and friction-modified conditions shows a substantial reduction in the wear coefficient from 1.6 × 10 −09 kg/Nm to 0.34 × 10 −09 kg/Nm, respectively. This along with an approximate 50% reduction in friction coefficient, is predicted to result in substantial decreases in corrugation growth rate and grinding costs of ∼20 times under the experimentally measured conditions of friction modifiers.

Monitoring of rail corrugation growth due to irregular wear on a railway metro curve

Short-pitch rail corrugation developing on the low rail in sharp curves is a problem experienced by many railway networks worldwide. Because of the large existence of small radius curves, metro lines are particularly affected. This case study is performed as part of a project which aims at developing a numerical tool for prediction of rail corrugation growth on curves. The development of corrugation on a 120 m radius curve of the Stockholm metro has been monitored by repeated measurements of rail roughness and train pass-by noise. Within a grinding interval of 1 year, severe short-pitch corrugation was build up with maximum peak-to-peak magnitudes of about 0.15 mm. Spectral analysis of measurement data shows large roughness magnitudes in the wavelength interval 4–14 cm, with peaks at approximately 5 cm and 8 cm. The corrugation pattern has a pure longitudinal direction (with corrugation ridges transverse to the track direction) and an irregularly varying magnitude along the 100 m long measured track section. The roughness growth rate increased with time until 300 days after rail grinding, thereafter only moderate additional roughness growth was observed. Because of moderate train speeds of about 30 km/h, the rolling noise caused by the corrugation has a low-frequency content (<200 Hz). A 10.1 dB unit increase (139–300 days after grinding) in roughness level in the wavelength interval 4–14 cm was found to correspond to an increase in rolling noise level in the frequency interval 60–200 Hz of 4.9 dB. In dry weather conditions, discomfort related to pass-by noise is rather linked to the occurrence of wheel squealing than to rolling noise.

Wear transitions in a wear coefficient model

The value chosen for the empirical wear coefficient in the frictional-work wear model greatly affects wear simulation results such as those for predicting rail corrugation growth. Furthermore, experimental results have widely shown that this wear coefficient is strongly dependent on the type of wear process involved, however these wear regimes are only defined empirically at present. This paper suggests a general model for the wear coefficient. Based on the wear mechanics involved, new analytical models for determining the wear transitions between wear types for wheel/rail steel is also proposed. The model predictions are in agreement with the available experimental data in the literature.

Rail corrugation growth—Influence of powered wheelsets with wheel tread irregularities

A multibody system model for simulation of general three-dimensional train-track interaction (accounting for frequencies up to several kHz) is used to investigate the hypothesis that rail corrugation is generated by powered wheelsets on the Swedish high-speed train X2. Part of the braking effort on the powered wheelsets is accomplished by tread braking with cast iron brake blocks. In particular, the influence of wheel corrugation, which is present because of such braking, on rail corrugation growth is studied. The numerical model uses an iteration scheme including simulation of dynamic train-track interaction in the time domain coupled with a long-term wear model. Measured wheel–rail contact forces and measured rail roughness are compared to the simulated results. Wheel–rail contact forces are considerably higher when wheel irregularities are present. However, the averaging effect from several passing wheelsets with different sets of wheel irregularities is found to give a rate of rail corrugation growth similar to the one obtained if the wheels had been completely round. The rail corrugation wavelengths are found to be explained by irregular wear due to high wheel–rail contact forces and slip caused by local rail bending modes between the two wheelsets in a bogie.

Prediction of the growth of wear-type rail corrugation

The growth behaviour of the vibrational wear phenomenon known as rail corrugation is investigated analytically and numerically using mathematical models. A simplified feedback model for wear-type rail corrugation that includes a wheel pass time delay is developed with an aim to analytically distil the most critical interaction occurring between the wheel/rail structural dynamics, rolling contact mechanics and rail wear. To this end, a stability analysis on the complete system is performed to determine the growth of wear-type rail corrugations over multiple wheelset passages. This analysis indicates that although the dynamical behaviour of the system is stable for each wheel passage, over multiple wheelset passages, the growth of wear-type corrugations is shown to be the result of instability due to feedback interaction between the three primary components of the model. The corrugations are shown analytically to grow for all realistic railway parameters. From this analysis an analytical expression for the exponential growth rate of corrugations in terms of known parameters is developed. This convenient expression is used to perform a sensitivity analysis to identify critical parameters that most affect corrugation growth. The analytical predictions are shown to compare well with results from a benchmarked time-domain finite element model.