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Proceedings of the Institution of Mechanical Engineers Part F: Journal of Rail and Rapid Transit
Journal Prestige (SJR): 0.494  Citation Impact (citeScore): 1 Number of Followers: 11  Hybrid journal (It can contain Open Access articles)ISSN (Print) 0954-4097 - ISSN (Online) 2041-3017 Published by Sage Publications  [1176 journals]
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- Numerical investigation on loading pattern of railway concrete slabs
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Authors: Hassan Liravi, Amin Khajehdezfuly, Javad Sadeghi, Peyman Aela, Yazdan Shafieyoon, Amir A. Shiraz
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
Despite the recent surge in the construction of ballastless railway tracks, there exists a notable research gap concerning the rail seat load (RSL) associated with these track types. The RSL is the load transferred from the rail to the fastening system, the plate beneath the rail and the rail pad. The prediction of RSL in ballasted track systems is widely investigated, however, there has been a relative lack of research into the ballastless railway track systems. In this paper, a 2D finite element model (2D FEM) was adopted to evaluate the RSL concerning the effective parameters, including sleeper spacing, fastening system stiffness and the flexural modulus of the rail. The numerical model was validated through a field test performed in the study. Moreover, a mathematical expression was proposed to determine the RSL ratio for concrete slab tracks. The RSL directly correlates with the sleeper spacing and the fastening stiffness, while this relation with the flexural rigidity is inverse. Based on the results, it was found that the RSL ratio obtained from the conventional methods differed considerably from the proposed mathematical expression. More specifically, this difference was observed in almost all of the values in the sleeper spacing and flexural rigidity of rail for the Kerr model except 0.68 m and 5 MN.m2, respectively.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-08-27T03:33:55Z
DOI: 10.1177/09544097241277577
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- Optimizing passengers’ experience: A goal-oriented reinforcement
learning speed control approach for urban railway trains-
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Authors: Wangyang Liu, Qingsheng Feng, Hong Li
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
Prolonged vibration can be uncomfortable for passengers utilizing urban rail transit systems. This study proposes an automatic speed control framework for urban railway trains to reduce vertical vibrations experienced by passengers. We suggest the concept of the “segmented comfort speed limit” to represent the vertical passing comfort of oncoming sections. This speed limit is calculated from 1/3 octave band acceleration and smoothed through lag-type speed control mode. The deep deterministic policy gradient algorithm with hindsight experience replay mechanism (HER-DDPG) is designed, to balance safety, comfort, and energy efficiency driving. Verify the speed control framework based on HER-DDPG through the rail data collected from Dalian Metro Line 12. Compared with the DDPG-based model, the vertical comfort is improved by 2.34%, and the longitudinal acceleration and total energy consumption are reduced by 45% and 8.1%. Compared with the real-world train control trajectory, HER-DDPG improves vertical comfort by 9.76% and reduces energy consumption by 12.4%. The results show that the proposed framework can effectively improve the ride experience of passengers.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-08-23T01:59:38Z
DOI: 10.1177/09544097241278012
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- The mechanism of polygonal wheel wear considering a three-dimensional
profile-
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Authors: Yaodong Fu, Muzi Wang, Dabin Cui, Ping Lu, Xinyi Li, Tao Liu
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
Wheel polygonal wear is one of the most serious problems in the railway industry nowadays. To study the mechanism of wheel polygonal wear, the wear prediction model was established. The three-dimensional wheel profile model and the improved USFD wear prediction algorithm were used to research the wear state of the wheel. The vehicle system dynamic characteristics and wheel wear state under different running speeds are studied. The results show that the vibration state of the wheel will be affected by the vertical and lateral coupling vibration of the wheel when considering the three-dimensional wheel polygonal wear. Due to the influence of coupled vibration, the wheel will appear larger wheel-rail force fluctuation points at different phase angles. The large wheel-rail force fluctuation at these different phase angles is one of the reasons for the formation of wheel polygonal wear. At the same time, the natural mode of the vehicle system will also affect the order of the wheel polygon and the amplitude of the wheel polygon. This study provides a new idea for the research of the wheel polygon mechanism.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-08-16T05:48:59Z
DOI: 10.1177/09544097241272753
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- Advances in research on the ballast bed stability on railway bridges
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Authors: Rong Chen, Hui Peng, Kai Liu, Juzhen Liu, Junfeng Li, Jianxing Liu, Ping Wang
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
The rapid development of high-speed railway bridges in China has brought enormous challenges to the ballast bed stability on the bridge. With the increase in the bridge span, the bridge deformation under the temperature load increases gradually, as well as the stability difference of ballast bed between different regions. Moreover, the track vibration response under high-speed driving conditions is larger, which can easily cause differential settlement, flying ballast, and deterioration of the ballast bed, thereby affecting the bearing capacity and stability of the ballast bed. In view of this, this article summarizes relevant research work on a ballast bed on the bridge from the perspectives of the resistance, deformation, and acceleration response of the ballast bed. In addition, this study discusses the existing measures for improving the ballast bed stability on the bridge, including the optimization of the sleeper and ballast bed structures. Finally, the main issues that need to be addressed to improve the ballast bed stability on the bridge are pointed out, and ideas for future research on ballast beds on bridges with different spans and structures are proposed.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-08-13T08:08:49Z
DOI: 10.1177/09544097241272888
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- Study on the allowed maximum amplitudes of low-order polygonal wear on
resilient wheels based on operational safety-
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Authors: Shuoqiao Zhong, Xin Zhou, Xiaozhen Sheng, Chuanlun Hou, Yuan Qi, Luis Baeza
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
Following the extensive use of resilient wheels on trams, several subways in China have started pre-launch testing of resilient wheels. While it remains at an early stage, the long-term behavior of the wheel has become a great concern for subway operators and wheel suppliers. To address the concern, this study focuses on derailment risk by evaluating the allowed maximum amplitudes of low-order polygonal wear on resilient wheels. Firstly, a metro vehicle-track dynamic system model equipped with resilient wheels is built. Then, based on the operation safety index and current re-profiling regulations for conventional wheels, the influence of wheel axial and radial stiffness on the radial amplitude limits of resilient wheel polygonal wear is analyzed. To perform the analysis, firstly the commonly-used stiffness for a resilient wheel (300 kN/mm in radial direction and 50 kN/mm in axial direction) is adopted to study the effect of resilient wheel polygonization on wheel load reduction ratio. Then, wheel load reduction ratio is predicted for different radial (up to 600 kN/mm) and axial (up to 100 kN/mm) stiffnesses of the resilient wheel and different orders (up to 10) of wheel polygonization of 1 mm amplitude. A contour plot is provided to illustrate how the wheel load reduction ratio varies with the harmonic order and amplitude of wheel polygonization under different combinations of resilient wheel’s equivalent axial and radial stiffnesses. It is found that, with the increase of the amplitude of the polygonal wear of a certain harmonic order on resilient wheel, the number of the available combinations of the equivalent stiffnesses adopted by the resilient wheel becomes less by considering the operation safety indexed with wheel load reduction ratio. Besides, depending on the stiffness of the resilient wheel, the allowed amplitude corresponding to the polygonization of each order has been suggested with the contour plots.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-08-07T03:33:44Z
DOI: 10.1177/09544097241272809
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- Modal coupling characteristics of primary hunting in metro vehicles:
Carbody suspension modes and hunting modes-
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Authors: Longfei Chen, Yong Wang, Huailong Shi
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
Due to coupling with carbody suspension modes in railway vehicles, primary hunting can lead to significant low frequency swaying of the carbody, severely deteriorating ride quality. In order to address this issue, this paper conducts a detailed investigation into the coupling effect between suspension modes and hunting modes of metro vehicles. Initially, a simplified lateral dynamics model is established, and a continuous modal tracking method is adopted for track suspension modes and hunting modes. The results indicate that when the modal frequency of one hunting mode approaches that of corresponding suspension mode, the damping ratio of the two modes exhibits abnormal variation, and the modal frequency curve veers or is slightly disturbed. In exploring the coupling characteristics of hunting modes and suspension modes, revealing the variation trends and similarity of modal shapes, polar diagrams of modal shapes are presented, and the correlation distance is calculated. Equivalent conicity exerts a substantial influence on the effect of modal coupling, influencing minimum damping ratio and modal shape similarity within the modal coupling zone. To ensure sufficient stability margin for metro vehicles, it is necessary to avoid excessively low equivalent conicity. Finally, the phenomenon of vibration response deterioration within the modal coupling zone is confirmed through both a simplified model and a full DOF model.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-07-23T07:17:57Z
DOI: 10.1177/09544097241266915
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- Research on the traction characteristic evaluation of urban rail vehicles
based on entropy weight TOPSIS-
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Authors: Aihua Zhu, Dongping Long, Cong Du, Jianwei Yang, Fan Zhang
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
This paper aims to investigate the influence of different speed at the end of the constant power section of the traction characteristic curve (TCC) on the vehicle dynamic performance and evaluate the TCC. A dynamics co-simulation model is developed in SIMPACK and MATLAB for dynamic analysis of the urban rail vehicle (URV) under different traction characteristics. Then it is used to investigate how acceleration distance and vehicle dynamic performance varies with the speed at the end of the constant power section of the TCC under different starting torques. Moreover, the entropy weight TOPSIS method which is widely used to solve the multi-objective decision-making problem is chosen to evaluate the traction characteristics based on various dynamic performance indexes over 25 test sections and acceleration distance. The results show that under traction conditions, the starting torque has effects on the lateral and vertical accelerations of car body, lateral and vertical wheel-rail contact forces, derailment coefficient and wheel unloading factor. The higher the torque, the greater the value of each index, that means the poorer the vehicle ride characteristics and running safety. For a given starting torque, the dynamic performance indexes increase with the increase of the speed at the end of the constant power section from 50 km/h to 80 km/h during the vehicle speed-up process. The maximum growth rate of the lateral and vertical accelerations of car body, lateral and vertical wheel-rail contact forces are 17%, 8%, 8% and 2%, respectively, when the speed at the end of the constant power section increases from 50 km/h to 80 km/h. Last, the comprehensive evaluation of traction characteristics using entropy-weight TOPSIS method reveals when the starting torque is 800 [math], 1000 [math], 1200 [math] and 1400 [math], the corresponding optimal speed at the end of the constant power section is 80 km/h, 80 km/h, 70 km/h and 50 km/h, respectively. The result of the study can provide theoretical support for traction characteristic design and traction control for URVs.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-07-22T05:51:56Z
DOI: 10.1177/09544097241250370
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- Effect of unsupported sleepers on vertical levelling loss of heavy-haul
railway track geometry under cyclic loadings-
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Authors: Andre Luis Oliveira de Melo, Sakdirat Kaewunruen, Mayorkinos Papaelias
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
With an emphasis on the combined degradation of railway track geometry and components, an improved numerical approach is proposed for predicting the track geometrical vertical levelling loss (VLL). In contrast to previous studies, this research unprecedentedly considers the influence of unsupported sleepers (US) configuration on VLL under cyclic loadings, elasto-plastic behaviour, and different operational dynamic conditions. The nonlinear numerical models are performed adopting an explicit finite element (FE) package, and their results are validated by field data. The outcomes are iteratively regressed by an analytical logarithmic function that cumulates permanent settlements, and by a power function factor, which innovatively extends the response of US on VLL over a long term. Results shows that at 3 million cycles (or 60 MGT) the worst configuration for 20-ton axle load is at 5 US with 5-mm gap (5,51%), whereas for 30 and 40-ton axle loads is at 5 US with 2-mm gap (1.23% and 0,89%, respectively). This indicates that the axle load affects considerably the VLL as expected, however, the US condition plays an important role to accelerate it. Based on this study, the acceptable configuration of US can be specified for a minimum effect on VLL (thresholds) and, therefore, supports the development of practical maintenance guidelines to prolong the railway track service life.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-07-22T02:41:37Z
DOI: 10.1177/09544097241266289
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- Analysis of the dynamic contact behaviour of high-speed train transmission
gear excited by wheel defects-
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Authors: Shuo Dou, Wenpeng Liu
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
Studies on wheel flatness and polygonal wear have demonstrated that wheel defects cause severe impact forces at the wheel–rail interfaces. This study investigated the dynamic contact mechanical behaviour of high–speed train transmission gears when subjected to wheel defects. First, a train-track coupling dynamics model was established, considering the localized contact characteristics of transmission gears. This model was developed using the slice method and the Hertz contact model, exploring the spatial coupling effects between the gear contact interface and the train–track interface. Subsequently, the dynamic model was employed to extract essential contact mechanical parameters of the transmission gear under the influence of wheel defects, including gear meshing load, gear contact stress, and sliding velocity. Furthermore, an analysis was conducted to uncover and elucidate the mechanism by which wheel flatness and polygonal wear impact the dynamic contact behaviour of the transmission gear. This study underscores the importance of considering wheel defects when assessing the contact fatigue and wear performance of high-speed train transmission gears.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-07-20T09:40:18Z
DOI: 10.1177/09544097241266873
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- Optimization algorithm for minimizing railway energy consumption in hybrid
powertrain architectures: A direct method approach using a novel
two-dimensional efficiency map approximation-
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Authors: Rahul Radhakrishnan, Moritz Schenker
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
SEnSOR (Smart Energy Speed Optimizer Rail) is a direct method based optimization algorithm developed at DLR for determining minimum energy speed trajectories for railway vehicles. This paper aims to reduce model error and improve this algorithm for any alternative powertrain architecture. Model simplifications such as projecting the efficiency maps of different train components onto one-dimensional space can lead to inaccuracies and non-optimalities in reality. In this work, 2D section-wise Chua functional representation was used to capture the complete behavior of efficiency maps and discuss its benefits. For this purpose, a new smoothing method was developed. It was observed that there is an average of 6% error in the energy calculation when both, 1D and 2D, models are compared against each other. Previously, solving for different powertrain architectures was time consuming with the requirement of manual modifications to the optimization problem. With a modular approach, the algorithm was modified to flexibly adapt the problem formulation to automatically take into account any changes in powertrain architectures with minimum user input. The benefit is demonstrated by performing optimization on a bi-mode train with three different power sources as developed within the EU-project FCH2RAIL. The advanced algorithm is now capable to adapt to such complex architectures and provide feasible optimization results within a reasonable time.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-06-22T04:01:07Z
DOI: 10.1177/09544097241237836
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- Dynamic characteristics of disc brake systems of a high-speed train with
wheel polygonal wear-
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Authors: Linchuan Yang, Huaqian Zhang, Peng Zhao, Zhiwei Wang, Chunguang Zhao, Jiliang Mo
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
The brake system is a key component of a high-speed train, which suffers intense wheel-rail interactions caused by wheel polygonal wear (WPW) in realistic working conditions. To explore the dynamic characteristics of the disc brake systems with WPW, a rigid-flexible coupled vehicle dynamics model is proposed. The developed model systematically takes into account the flexible deformation of brake components and wheelsets, measured WPW and non-linear factors such as wheel-rail interaction, disc-pad friction and non-linear damping characteristics. It allows the dynamic behaviors of the vehicle brake system in service to be accurately and effectively revealed. The model is verified using line test data, and then the dynamic characteristics of disc brake systems with WPW are investigated in details. The results show that for vehicle speed below 80 km/h and depths of WPW below 0.04 mm, the effect of WPW on the vibration of the caliper is slight. However, as vehicle speed and wear depth continue to rise, the vibration of the caliper increases noticeably. Furthermore, the effects of vehicle speed and wear depth on brake disc vibration are more obvious, and increasing vehicle speed and wear depth will steadily deteriorate the vibration of the disc. Besides, the effect of WPW is particularly pronounced on the dynamic behavior of the brake units closer to the wheels. Overall, the influence of wheel polygon cannot be neglected in the study of dynamic characteristics of brake system. At the same time, the proposed model can also be applied in the strength evaluation of brake components and the study of the tribological behaviors within the brake interface.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-06-21T09:38:31Z
DOI: 10.1177/09544097241264322
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- Analysis of rail corrugation deterioration behavior on a heavy-haul
railway-
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Authors: Jing He, Weiqi Wang, Quan Zhang, Wenkun Wang, Nengpu Yang
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
Rail corrugation is a common form of rail damage discovered when servicing heavy-haul railways that seriously affects the safety of wheel–rail systems. To determine the characteristics of the deterioration of a corrugated heavy-haul railway, this study used ABAQUS simulation software to establish a three-dimensional elastic–plastic wheel–rail finite element model. We then simulated the stress and strain distributions of wheel–rail contact spots as C80 freight cars pass through various corrugated sections of heavy-haul railways, featuring different wavelengths and wave depths. The simulation results demonstrated that the stress and strain increase from the peak positions to the troughs, reaching a maximum somewhere behind the troughs, and then decreasing to the next peak. The stress and strain increase as the depth of corrugation increases. The wheel–rail contact exhibits a maximum stress of 1.312 to 1.770 GPa, and the maximum strain is 0.6470% to 0.9897%. Wheel–rail contact stress and strain occur at a maximum of 8–40 mm after the troughs, rather than at the trough position, forming “planing and rolling” effects. This mechanism revealed by the variation in the stress and strain distributions in this study provides a reference for the in-depth analysis of rail corrugation deterioration and for the exploration of the mechanisms of corrugation deterioration of heavy-haul railways.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-06-21T01:45:32Z
DOI: 10.1177/09544097241262360
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- Natural rail fracture defect calibration using infrared thermography and
edge detection-
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Authors: Ranting Cui, Chaojun Wei, Yuning Wu, Keping Zhang, Xuan Zhu
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
Rail breakage can cause train derailment that leads to catastrophic consequences, prevention of which is worthy of a significant amount of investment in finance and time. Non-destructive evaluation can provide qualitative and quantitative inspection of rail tracks in-situ to detect dangerous faults, even though these defects are primarily invisible or hardly noticed from the surface of the rail. To make it efficient and convenient, infrared thermography technique offers a remote operation without interfering with rail transportation. The image processing for edge detection can further quantify the defect deterioration by depicting the contour of the defect. Moreover, the optimal parameters for various edge operators provide reliable detection for natural fracture defects.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-06-19T08:38:21Z
DOI: 10.1177/09544097241262866
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- Monitoring the bogie lateral dynamics of a high-speed train through
wireless sensor nodes-
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Authors: Carlos Esteban Araya Reyes, Federico Zanelli, Francesco Castelli-Dezza, Stefano Bruni
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
The condition monitoring of railway vehicles and of the infrastructure (track and overhead equipment) through the use of vehicle-based sensors is becoming a major trend for the railway industry and, to this aim, new rolling stock generations are often natively fitted with numerous sensors. However, older vehicles are not equipped with sensors and monitoring systems so that, considering the long service life of the rolling stock, advanced monitoring and condition-based maintenance techniques can only be applied to a relatively minor portion of the in-service railway fleets. This paper presents results from a research programme aimed at designing and testing an innovative monitoring system based on wireless sensor nodes, suitable for the retrofitting of older rolling stock generations, not natively equipped with advanced sensing and monitoring capabilities. The prototype monitoring system was used to detect the incipient bogie instability, which can be related to degradation in some suspension components or to increase of the equivalent conicity at wheel/rail contact. Different vehicle conditions and the influence of the track were considered in the study. Experimental tests have shown that is possible to identify not only how the vehicle condition is evolving in time but also the effect that maintenance operations like wheel reprofiling may have on the bogie lateral dynamics.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-06-17T08:09:48Z
DOI: 10.1177/09544097241262074
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- Carbody hunting behaviour of high speed vehicles in low effective conicity
of wheel-rail contact-
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Authors: Biao Zheng, Lai Wei, Jing Zeng, Caihong Huang
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
In the past, bogie hunting instability garnered more attention due to its potential for causing serious safety issues. However, with the rise in high-speed vehicle speeds and operational mileage, the concerns arising from carbody hunting can no longer be overlooked. This article investigates the causes and solutions for low-frequency carbody swaying under low effective conicity in wheel-rail contact, employing a combination of experimental and numerical techniques. Initially, the study involves an in-depth analysis of time-domain signals from lateral and vertical accelerations of the carbody and bogie frame during a high-speed train field-test. The carbody vibration mode resulting from carbody hunting displays a swaying motion at a frequency of 1.5 Hz. Subsequently, a dynamic system model of the high-speed vehicle was established and the suspension mode of the model were verified. The frequency of the carbody upper sway motion is determined to be 1.39 Hz. Low effective conicity is induced when grinding wheel match with new rail or new wheel match with grinding rail. Under this low effective conicity, the hunting frequency of the vehicle is around 1.5 Hz, close to the frequency of the carbody upper sway motion. The coincidence of the hunting frequency and the upper sway motion frequency leads to the low-frequency swaying of the carbody. At last, the effects of wheel profiles, rail profiles and suspension parameters on the carbody hunting have been studied. The study demonstrates that addressing low-frequency carbody swaying can be achieved through targeted rail grinding. This process involves modifying the rail profile while ensuring careful grinding of the rail inner corner. Furthermore, it has been confirmed in the article that replacing suitable yaw dampers is also effective.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-06-14T01:46:25Z
DOI: 10.1177/09544097241262395
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- Study on the generation mechanism of curve squeal and its relationship
with wheel/rail wear-
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Authors: Xiaohang Feng, Guangxiong Chen, Bingjie Dong, Qifeng Song, Wenjuan Ren
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
This paper aims to create a friction coupling finite element model of the wheelset–track system, taking into account various curve radii and corresponding wheel/rail contact states. This model will serve as a tool to analyze the underlying causes of curve squeal phenomena. Furthermore, we conducted an investigation into the impact of rail and wheel wear on system stability. This paper utilized a complex eigenvalue analysis (CEA) method to accurately calculate and predict vibration instabilities in the system. The results show that the smaller the radius of the curve, the more prone to it is lateral creep between the rail and the leading wheelset, so that the system is more prone to self-excited frictional vibrations, ultimately resulting in the generation of curve squeal. In addition, the wear of the wheel tread/rail head increases the instability of the system. When the train passes through a section with rail corrugation, rail corrugation suppresses the occurrence of curve squeal.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-05-30T05:39:36Z
DOI: 10.1177/09544097241257290
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- Rail profile optimization of a subway’s sharp curve considering multiple
curve sections and metal removal-
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Authors: Shuguo Wang, Jingmang Xu, Caiwei Liu, Yao Qian, Ping Wang, Pu Wang, Qiantao Ma, Boyi Liu
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
In order to effectively address the engineering problem of optimizing the worn rail profile on subway sharp-radius curves, this paper focuses on the inconsistent wear characteristics of rails on such curves. The contact stress, wheel-rail lateral force, and wear index are taken as objective functions, and key rail profiles at the points of straight-transition, transition-curve, curve-midpoint, circular-transition, and transition-straight are selected. A multi-objective and multi-section optimization scheme based on the optimized limit curve is proposed to design the grinding profile for rails on subway sharp-radius curves. In order to compare its optimization effectiveness, two additional optimization schemes are presented: the second scheme involves multi-section profile optimization with no optimized limit curve as constraints, and the third scheme deals with optimizing a single profile for grinding with equal cross-sections. Through a comparison of the three optimization schemes, the results indicate that all three schemes lead to a reduction in the contact stress, wheel-rail lateral force, and wear index of the outer and inner stock rails after optimization. Scheme 1 shows a more extensive and uniform distribution of wheel-rail contact points, with larger reductions in contact stress and increases in contact area. Scheme 3 only improves contact in severely worn sections, while in less worn sections, the contact distribution becomes concentrated, accelerating wear evolution. Furthermore, in Scheme 1, the cumulative wear after 100,000 and 200,000 cycles is reduced by a maximum of 8.44% and 22.33% compared to before optimization, making it the most effective among the three schemes. Therefore, the optimized profile output by the optimization method proposed in this paper is considered the best solution, which is represented by Scheme 1.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-05-30T05:08:25Z
DOI: 10.1177/09544097241257551
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- On the implementation of hydraulic-interconnected-suspensions at the
primary suspension stage of high-speed rail vehicles-
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Authors: Gioele Isacchi, Francesco Ripamonti
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
In recent years, huge investments have been made to improve the dynamic performance of high-speed trains. Research into innovative suspension components has been part of the development of this transport system for decades. Innovative devices can allow rail vehicles to deal with the constantly increasing speed required by the global market. Among the most innovative suspension layouts proposed in railway dynamics in past years, limited attention has been given to Hydraulic Interconnected Suspensions (HIS). This layout is composed of two hydraulic cylinders with external hydraulic connections. Hydraulic Interconnected Suspensions allow promising tuning capabilities due to their ability to offer different responses based on the specific inputs given to the cylinders. This layout is rarely considered for rail vehicles, and the few previous works related to this topic considered the HIS layout to be applied at the secondary suspension stage. In this context, this paper proposes applying an HIS layout to the primary suspension stage of rail vehicles, in order to overcome the trade-offs between ride comfort, running safety and maximum car body displacement that need to be considered by bogie manufacturers when designing and optimising these mechanical systems. A nonlinear physical model of the HIS is proposed for co-simulation with a Multi-body (MB) model of a high-speed train. The improvement provided implementing an HIS at the primary suspension stage is then compared to similar enhancements that could be made when tuning and varying the standard suspension components of a bogie.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-05-29T05:49:16Z
DOI: 10.1177/09544097241257550
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- Field investigation on the effect of the tamping machine and dynamic track
stabilizer on changing the rail support modulus-
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Authors: Aliakbar Abbasi, Jabbar Ali Zakeri, Ehsan Norouzi, Seyed Ali Mosayebi
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
Due to increasing train speed and passage tonnage, the repair and maintenance of ballasted railway tracks is essential. As a result of cyclic train loads on ballasted tracks, the ballast layer can deteriorate. When the ballast bed deteriorates, it can change the track geometry, which leads to uncomfortable ride and an increase in wheel-rail interaction. Tamping is one of the most widely used methods for filling the ballast layer gaps around sleepers and homogenizing ballast beds in order to align the track geometry. After passing the tamping machine, the dynamic stabilizing machine is utilized to improve the quality of the ballast bed. The rail support modulus is an essential parameter for analyzing ballasted railway tracks, and it can change after maintenance operations. This paper extensively discusses the effects of maintenance operations on rail support modulus as an essential safety factor in ballasted tracks. In this study, a series of field tests are planned and conducted at Karaj station in Iran to investigate the effects of passing tamping and stabilizing machines on the rail support modulus in ballasted tracks. In this regard, the rail support modulus of the ballasted track according to deflection basins was measured in three stages (before tamping, after tamping, and after stabilizing), and the results were analyzed to determine the effects of passing maintenance machines on ballast beds. Based on the results, the tamping operation results in a 75.5% reduction in the rail support modulus, and after stabilizing the railway track, the rail support modulus is increased by 35.8%.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-05-22T03:13:56Z
DOI: 10.1177/09544097241255718
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- High–speed train crash safety assessment for Train–moose
collisions-
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Authors: Yong Peng, Zhengsheng Hu, Min Deng, Kui Wang, Yangyang Yu, Quanwei Che, Gongxun Deng
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
The increasing number of train–moose collision accidents threatens train running safety. This study investigated the bullet train–moose collision process and explored the effect of parameters on the dynamic responses. The multibody (MB) model was developed and validated against real–world collisions and the validated finite element model. A parametric study including the moose size, train speed, moose velocity, moose offset, and impact angle was conducted using MADYMO software. The lateral and longitudinal displacements of the moose’s center of gravity (CG) were used to evaluate the crash safety. The results showed that the moose size significantly affects moose impact dynamics and kinematics. The velocity and the offset of the moose were positively correlated with the lateral displacement. However, there was an obvious nonlinear relationship between the train speed and the lateral displacement. With the increase in the collision speed, the front–end deformation weakens the obstacle removal effect of the front hatch. The landing spots of the small–sized moose were the most concentrated, which means greater risk of secondary collisions. This study provides practical help for improving the running safety of high–speed trains and protecting wild animals along railways.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-05-14T07:03:19Z
DOI: 10.1177/09544097241254146
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- Improving the mechanical performance of railway concrete sleepers using
recycled materials: An experimental and numerical study-
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Authors: Jun Wang, Mohammad Siahkouhi, Yunchang Du, Gang Huang, Xiaodong Han, Guoqing Jing
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
This paper explores the use of three waste materials available in vast quantities, including waste tires, glass bottles and bamboo furniture, in the manufacture of railway sleepers. Mechanical properties of recycled concrete have been studied to establish an optimal mix suitable for concrete railway sleeper manufacturing. Thus, 5%, 10%, 15% and 20% recycled rubber sands (RRS) by volume of fine aggregate are used instead of 30# and 60# mesh sizes of fine aggregate. Moreover, 20%, 40%, 60%, 80% and 100% of aggregate volume are replaced by recycled glass aggregate (RGA) particles. Furthermore, different percentages of recycled bamboo fibers (RBF) have been used as 1%, 2% and 3% by volume of concrete. According to the optimal concrete mixtures of RRS, RGA and RBF, twelve concrete railway sleepers are manufactured and tested for middle and rail seat bending strengths. Results show that ref. sleeper has almost 16% and 24% lower strengths than RGA sleeper in middle and rail seat, respectively, while ref. sleeper have higher strengths by 16% and 13%, and 18% and 7% than RRS sleeper (M60-R5) and RBF sleeper (B2) in middle and rail seat, respectively. The FEM results show that the ([math]) of the RGA sleeper is the minimum ratio by 1.11 and 1.13 for rail seat and middle of sleeper, respectively, which is the best performance. In RBF sleeper FEM model, Bamboo fiber can only bear 5% and 8% of total stress in middle and rail seat, respectively, due to low mechanical properties of fibers.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-05-11T06:09:31Z
DOI: 10.1177/09544097241241356
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- Investigation of curve minimum radius in heavy-haul railway to improve
wheel wear evolution and wheel-rail contact geometry-
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Authors: Pengfei Liu, Kai Hao, Chen Wang, Meiqi Wang, Ao Wang, Zida Xing
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
To determine the minimum and reasonable radius of horizontal curve for reducing wheel wear in heavy-haul railway design, a HXD locomotive with the wheel arrangement of C0-C0 is taken as the research object. Both the corresponding locomotive dynamic model and wheel wear model are established. Based on the measured wear data in a specific line, the simulation model is verified with the prediction error of wheel wear depth below 0.5 mm in general. The wheel wear evolution rules in 400∼1000m radius curves are studied and compared. The results indicate that, the wheel wear is large and sensitive to curve radius within 400∼600 m. The larger radius curve will be helpful to reduce wheel flange contact and wheel wear. For curve radius increasing from 600m to 1000m, the wheel average wear reduces slowly. Especially for curve radius below around 740 m, the wheel flange wear will be predominant. For radius above 740m, the wheel tread wear becomes the main wear form and the wheel flange wear can be reduced significantly. The increase of curve radius will also improve the wheel-rail equivalent conicity. If the minimum curve radius is set as 800m, the equivalent conicity difference between new wheelset and 1st ∼ 3rd worn wheelset can be kept below 21%, 52% and 9% respectively. In this case, the equivalent conicity is closest to the initial state and reaches a steady state, which will not change significantly with the radius further increasing. Viewed from the aspects of reducing wheel wear, avoiding wheel flange contact and keeping conicity stable simultaneously, the minimum radius of horizontal curve should be limited to 800 m. The research results validate the minimum curve radius suggested in Code for Design of Heavy-haul Railway in China, and provide a scientific explanation for the determination of this value.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-05-06T08:57:02Z
DOI: 10.1177/09544097241248205
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- Surrogate-based aerodynamic shape optimization of high-speed train heads:
A review of four key technologies-
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Authors: Hongbo Wang, Shuangbu Wang, Dayuan Zhuang, Zaiping Zhu, Pengcheng You, Zhao Tang, Guofu Ding
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
With the increase in running speed, the aerodynamic characteristics of high-speed trains have a significant impact on running stability, energy consumption and passenger comfort. Since the shape of the high-speed train head can directly influence the surrounding airflow, optimizing the head shape is the primary way to improve the aerodynamic performance of the train. This paper reviews current research studies on the surrogate-based aerodynamic shape optimization of high-speed train heads, aiming to provide a comprehensive reference for designers to enhance design efficiency and optimization performance. The entire optimization process is divided into four essential steps, and the key optimization technologies in each step are discussed, including parametric modeling, computational fluid dynamics (CFD) simulation, surrogate model and optimization algorithm. By introducing the practical applications of these technologies, we summarize their advantages and disadvantages and suggest four potential research directions for the future.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-05-06T08:20:48Z
DOI: 10.1177/09544097241251509
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- Cavity noise reduction of a high-speed train pantograph through jet
parameter optimization-
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Authors: Ziheng Zhang, Xiaodan Miao, Daowei Liu, Ruigang Song, Tianchen Yuan, Jian Yang
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
The effect of aerodynamic noise from high-speed trains on residents living near railway lines is a critical issue. The pantograph cavity is considered to be a major source of aerodynamic noise. To address this problem, this study proposes the application of jetting at the leading edge of the cavity, directly targeting noise reduction at its source. The large eddy simulation approach is used for flow calculations, and the Ffowcs Williams and Hawkings aeroacoustic analogy is adopted for far-field acoustic predictions. Orthogonal designs and the backpropagation algorithm optimized by the genetic algorithm (BP-GA) is used to explore the effects of jetting factors on noise and identify the optimal parameters. Orthogonal design analysis shows that the most influential among the factors is jet orifice diameter, followed by jet velocity and jet angle. The use of the BP-GA algorithm for optimization reveals that the optimal jet parameters are jet velocity of 118.28 m/s, jet angle of 3.17°, and jet orifice diameter of 76.74 mm. The algorithm predicts a minimum noise level of 91.04 dB, which is close to the simulated noise level of 90.74 dB. The jetting process achieves a maximum noise reduction of 4 dB. Results demonstrate that the proposed method for cavity leading edge jetting effectively reduces turbulent kinetic energy and horseshoe-shaped vortices in the cavity, leading to noise reduction. This method also minimizes the effects of aerodynamic noise on distant areas, such as waiting areas and residential buildings. This work provides a theoretical basis for increasing high-speed train speeds.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-05-06T07:24:06Z
DOI: 10.1177/09544097241251912
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- Dynamic behaviour of bridges under critical conventional and regular
trains: Review of some regulations included in EN 1991-2-
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Authors: Pedro Museros, Andreas Andersson, Benjamín Pinazo
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
In the field of structural analysis dedicated to the study of vibrations of high-speed railway bridges, one reference load model is the well-known HSLM-A, which limits of validity are stated in Eurocode EN 1991-2, Annex E. In a recent paper published in the Journal of Rail and Rapid Transit, the authors investigated the degree of coverage provided by HSLM-A to critical articulated trains. Now in the present article, the authors have extended those analyses to critical conventional and regular trains as well. This is an important aspect because HSLM-A as such is an articulated-type model, so it is of interest to understand how it deals with covering the various resonance phenomena generated by other train types. Therefore, the main goal of this work is to establish whether the conventional and regular trains that stem from the validity rules given in Annex E/EN 1991-2, produce vibratory effects that are duly covered by HSLM-A. Following the aforementioned validity rules, one first aspect analysed is the importance of near-to-integer wheelbase ratios in the coupled vibrations produced by conventional trains. Subsequently, seven realistic, conventional and regular high-speed train models have been synthesised; these models have been made publicly available in Mendeley Data, and comprise almost 3800 different sequences of axle loads. Finally, the response of simply-supported bridges has been analysed with a view to compare the seven synthesised models versus HSLM-A. The exceedance and required speed increase have been computed for both displacements and accelerations, in a comprehensive ensemble of spans and speeds. The results provide a diagnosis of the degree of coverage of HSLM-A with respect to those conventional and regular trains compliant with Annex E/EN 1991-2.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-04-29T09:15:56Z
DOI: 10.1177/09544097241245150
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- Nonlinear impedance characteristics of a gas hydraulic energy absorber and
performance prediction for railway transportation of valuable goods-
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Authors: Wenlin Wang, Hongyou Liu, Dazhuo Wu, Yongming Wu, Jian Zhao
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
It is meaningful to investigate the nonlinear impedance characteristics of gas hydraulic energy absorbers (GHEAs) and their potential application in modern railway transportation of valuable goods. Fluid-mechanics-based full parametric modelling of a GHEA used in a high-speed train is performed, both simulations with the developed mathematic model and physical experiments are carried out on the static and dynamic characteristics of the GHEA. The agreement between the results of the simulation and the experiment with tolerable deviations validates the nonlinear mathematic model. Longitudinal train dynamics (LTD) modelling and simulation of a Chinese rapid freight train with the validated GHEA model or the conventional MT-2 friction-type energy absorber model is finally conducted. The results show that when the train uses GHEAs instead of MT-2 energy absorbers, the coupler forces and vehicle accelerations of the train are significantly reduced, and the vehicles operate more steadily in situations such as train startup, emergency braking and shunting operations; thus, gas hydraulic energy absorber is protective and would be alternative for equipping rapid freight trains for the transportation of valuable goods. The obtained nonlinear mathematic model in terms of the structural, oil and gas property parameters of the GHEA is useful and meaningful in further parameter design optimization of GHEAs and optimal specification of GHEAs for rapid freight trains.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-04-29T06:55:47Z
DOI: 10.1177/09544097241249504
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- An investigation into the constitutive relation of corrugated metro rail
material based on nano-indentation experiment and inverse analysis-
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Authors: Shuai Chen, Guotang Zhao, Jian Han, Ping Wang, Hengyu Wang
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
To establish the constitutive relation of corrugated rail material, rail corrugation was reproduced. The material mechanical properties of corrugation peaks and troughs were obtained by experiment. A set of dimensionless functions was proposed for the elastic modulus, hardness and yield stress at arbitrary depth of corrugation peaks and troughs. By combining the finite element model and dimensional functions, the constitutive relations were obtained at different vertical and lateral positions of corrugation. The closer the material is to the rail surface, the larger the mechanical property values. The elastic modulus and hardness of corrugated rail material at the trough surface are higher than those at the peak, while the yield stress at the peak surface is higher than the trough.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-04-25T03:19:25Z
DOI: 10.1177/09544097241245598
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- Wheel-rail contact wear analysis on curved lubricated track for heavy haul
locomotive studies-
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Authors: Yan Quan Sun, Maksym Spiryagin, Qing Wu, Colin Cole
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
The effect of lubrications on a curved track to heavy-haul wheel-rail contact wear is studied. To analyse wheel-rail contact wear damage due to existing high-adhesive AC locomotive, a methodology for investigation is proposed, and the locomotive models are required to run at 20 km/h under maximum traction efforts, and the simulations include a DC locomotive for comparison. An extended creep force model, which was developed by Polach and has been widely used for the wheel-rail contacts under dry and wet conditions with variable friction coefficients, is further extended to apply for the typical low-coefficient-friction modifier, oil, and grease lubricant conditions. The wear models from two pairs of wheel-rail materials are used to predict the wear rates, and the wear numbers Tγ are presented for discussions. The simulations show that the lubricants significantly reduce the wheel-rail contact wear.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-04-03T09:06:13Z
DOI: 10.1177/09544097241244411
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- Force transmission and height adjustment stability of the new height
adjustable long pillow ballastless track-
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Authors: Zhenxing He, Cheng Luo, Shuzhen Wang, Jianfeng Yun, Quanbao Feng
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
To address the settlement issue in high-speed railway foundations, the present study introduces a novel ballastless track system called NHABT (New height-adjustable ballastless track). This paper outlines the structural characteristics of the track and provides a detailed explanation of the methodology employed for height adjustment. To account for the unique properties of the NHABT structure, this study establishes finite element and vehicle-track coupling dynamics models. Firstly, under wheel load conditions, the study investigates the stress distribution of the NHABT structure and analyzes the influence of track bed length, thickness, and height adjustment on the force transfer characteristics of the NHABT structure. Secondly, the impact of height adjustment on the quality of vehicle operation and the stability of the NHABT structure is examined. The results indicate that adjusting the NHABT structure within a range of 20 to 200 mm is achievable by changing the side support pad or sleeper. The maximum stress occurs in the folded corner area on both sides of the sleeper groove. The force transfer characteristics of the NHABT structure are not affected by the length of the track bed, but its thickness significantly influences the stress in the folding corner area of the sleeper groove. The vehicle running quality and the stability of the NHABT structure after the adjustment are maintained at the same level as before the adjustment.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-03-28T05:49:48Z
DOI: 10.1177/09544097241241418
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- Novel in-situ real-time line scan optical monitoring of wear and surface
damage initiation in a laboratory twin disc test-
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Authors: Adam PG Wilby, Jacob Corteen, Roger Lewis, David I Fletcher
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
A new optical monitoring system has been developed to photograph in-situ in real time the initiation of damage on the running surface of a rail steel twin-disc sample undergoing wear testing. The line-scan camera system has been demonstrated on the Sheffield University ROlling Sliding 2 (SUROS2) twin-disc machine. The results show the system can continuously track the development of wear flakes, with wear flake initiation and stabilisation of wear flake size observed without test interruption for the first time. Image analysis to quantify the total wear flake shadow pixel count showed a good correlation with the mass loss results, indicating the potential for the optical data to quantify rail steel wear without interruption to testing. Furthermore, in a water-lubricated test the new system enables observation of rolling contact fatigue (RCF) crack initiation through a water layer present on the specimens, without requiring test interruption. The improving knowledge of the wear and RCF performance of rail steels available from the new observation method can help improve understanding of steel performance and support to the selection of rail steel grades according to their performance.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-03-26T11:52:29Z
DOI: 10.1177/09544097241242169
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- Using digital image correlation (DIC) to measure railway ballast movement
in full-scale laboratory testing of sleeper lateral resistance-
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Authors: Jacob W Whittle, Stephen Danks, Iwo Słodczyk, David I Fletcher
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
A fast and accurate method is described for determining the surface movement of railway ballast during a full-scale lateral resistance test. The proposed method utilises commodity camera equipment and open-source Digital Image Correlation (DIC) algorithms, to track individual ballast particles. It does not require time intensive ballast preparation. Tests have been performed under ambient and floodlit conditions, using colour and greyscale processing routes. The results are compared against direct measurements from lateral resistance tests to assess the accuracy of the proposed method, with a range of absolute maximum error between 0.9% and 3.4% under different laboratory conditions. The study shows that this technique is a viable way to track and measure ballast and sleeper movement over wide areas in near real time, which will lead to an increased understanding of the way ballast interactions influence track behaviour.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-03-21T07:16:39Z
DOI: 10.1177/09544097241241102
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- Wheel wear prediction for high-speed trains by considering wheel-rail
elastic deformation-
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Authors: Gengzhuo Miao, Ren Luo, Huailong Shi
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
Wheel-rail geometric parameters are crucial for determining wheel wear in high-speed trains. Under the action of a wheel-rail load, both the wheel and rail suffer elastic deformation, which affects the wheel-rail contact relationship and further influences the wheel profile and its evolution. In this study, a field test was conducted on a high-speed train operating at 250 km/h, and the worn wheel profiles and wear curves were continuously measured for one reprofiling cycle. Subsequently, a vehicle dynamics model is built using a wheel wear prediction model based on the integrated USFD wear algorithm. In this model, the finite element model of the wheel-rail contact is considered. The wheel-rail geometric parameters are obtained by determining their elastic deformation through the finite element method, which considers the effect of three parameters: the track gauge, back-to-back space of the wheelset, and rail cant. After considering the wheel-rail elastic deformation, the track gauge decreases from 1435 to 1434.5 mm, the back-to-back space varies from 1353 to 1352.3 mm, and the rail cant changes from 1:40 to approximately 1:37. Finally, the simulation and experimental results are compared, revealing that the wheel-rail elastic deformation has a significant impact on the wheel wear after the vehicle travels 150,000 km. The wear depth and wheel-rail equivalent conicity after considering the elastic deformation are closer to the measured results.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-03-09T12:20:27Z
DOI: 10.1177/09544097241239089
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- Wheel profile optimization for intercity EMUs based on the Gaussian
function correction method-
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Authors: Maorui Hou, Yayun Qi, Changxin Chi, Peng Ao, Hua Liu
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
Intercity EMUs are prone to wheel flange wear and tread wear due to the high operating speed and many small radius curved tracks. The problems caused by wheel wear have seriously affected the safety of high-speed railway operations in China. In this paper, based on the original LMA wheel profile, the Gaussian function correction (GFC) method is proposed to design the wheel profile. The GFC method mainly changes the root region of the wheel flange, to enhance the curve passing performance and reduce wheel wear of the vehicle. The optimal profile is optimized by the Kriging surrogate model (KSM) and the whale optimization algorithm (WOA). The wheel-rail contact characteristics, dynamic characteristics and the wheel wear of the wheel profiles before and after optimization are simulated and analyzed. The results show that the equivalent conicity of the optimized profile is reduced; the critical speed is increased by 9.3 km/h, the lateral ride index and comfort index of the vehicle are further reduced. The curve passing performance is also improved, the wheel-rail wear of the optimized profile is further reduced and the maximum wear depth of the wheels before and after optimization is 43.4e-9m and 34.1e-9m on the curved track with a radius of 500m, which is reduced by 21.43%. This method provides a reference and basis for wheel profile design and profile re-profiling of intercity EMUs.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-02-27T09:35:29Z
DOI: 10.1177/09544097241229142
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- Multi-modal battery-operated trains on partially electrified lines: A case
study on some regional lines in Italy-
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Authors: Luca Pugi, Luca di Carlo
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
A full electrification of many local railway lines is often not feasible or sustainable in terms of construction and maintenance costs or alternatively for the presence of additional constraints and limitations deriving from environmental or infrastructural limitations. Battery Operated Powertrains or other kind of hybrid solutions are currently proposed as sustainable alternatives to internal combustion engines for the propulsion of rolling stock on non-electrified lines. In this work, the authors propose the adoption of a partial electrification of lines to assure higher performances and reliability of battery-operated rolling stock designed to be recharged and feed using standard technologies such as pantographs gathering power from suspended catenaries. This innovative solution is designed for a benchmark test vehicle inspired from an existing one and simulated considering some possible scenario of application corresponding to some existing railway lines in Italy.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-02-26T04:50:19Z
DOI: 10.1177/09544097241234959
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- Analysis of settlement thresholds for a new ballastless track-concrete box
subgrade structure-
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Authors: Zhihui Zhu, Yongjiu Tang, Weiqi Zheng, Yu Qin, Lei Yu, Xiang Wang
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
In this paper, the effects of settlement on force, track deformation, and train dynamics to determine the settlement thresholds of ballastless track-concrete box subgrade (BTCBS) are studied. Firstly, this study introduces four settlement types, namely V-shape, box rolling, box faulting, and trapezoid settlement. The nonlinear finite element model (FEM) of BTCBS and the train-ballastless track-concrete box subgrade (TBTCBS) model considering nonlinear contact between track slabs and base slabs are established. Then, the effects of settlement on fastener force, track deformation, and vehicle dynamics are studied. According to the calculated results and China’s codes, the settlement limit values of BTCBS can be obtained. The results indicate that the settlement thresholds with box rolling and faulting are controlled by vertical force of fasteners, and the settlement limit values with V-shape and trapezoid settlement are controlled by 10 m chord versine of vertical irregularity (CVVI). The suggested settlement limit values of BTCBS for box faulting, box rolling, trapezoid, and V-shape settlement are respectively 2.48 mm, 2.55 mm, 17.43 mm, and 8.79 mm.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-02-19T12:56:54Z
DOI: 10.1177/09544097241234704
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- A rail fastener defect detection algorithm based on improved YOLOv5
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Authors: Ling Wang, Qiuyu Zang, Kehua Zhang, Lintong Wu
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
Being a crucial component of railway tracks, monitoring the health condition of fasteners stands as a critical aspect within the realm of railroad track management, ensuring the normal passage of trains. However, traditional track fastener detection methods mainly use artificial checks, giving rise to challenges encompassing reduced efficiency, safety hazards, and poor detection accuracy. Consequently, we introduce an innovative model for the detection of track fastener defects, termed YOLOv5-CGBD. In this study, we first imbue the backbone network with the CBAM attention mechanism, which elevates the network’s emphasis on pertinent feature extraction within defective regions. Subsequently, we replace the standard convolutional blocks in the neck network with the GSConv convolutional module, achieving a delicate balance between the model’s accuracy and computational speed. Augmenting our model’s capacities for efficient feature map fusion and reorganization across diverse scales, we integrate the weighted bidirectional feature pyramid network (BiFPN). Ultimately, we manipulate a lightweight decoupled head structure, which improves both detection precision and model robustness. Concurrently, to enhance the model’s performance, a data augmentation strategy is employed. The experimental findings testify to the YOLOv5-CGBD model’s ability to conduct real-time detection, with mAP0.5 scores of 0.971 and 0.747 for mAP0.5:0.95, surpassing those of the original YOLOv5 model by 2.2% and 4.1%, respectively. Furthermore, we undertake a comparative assessment, contrasting the proposed methodology with alternative approaches. The experimental outcomes manifest that the YOLOv5-CGBD model exhibits the most exceptional comprehensive detection performance while concurrently maintaining a high processing speed.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-02-17T10:43:24Z
DOI: 10.1177/09544097241234380
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- Feature analysis of precipitation-induced subgrade defects on a high-speed
rail ballasted track using multiple track inspection data: A case study-
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Authors: Junhua Xiao, Yingqi Bai, Chengjie Song, Siqi Sun, Xiaozhou Liu
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
Heavy rainfall has posed a great challenge to the service performance of high-speed rail (HSR) substructure, resulting in a reduction in the ride quality and safety of high-speed trains. To carry out proper repair work for the substructure, it is imperative to realize efficient identification of precipitation-induced subgrade defects. To this end, this paper aims to extract the features of typical precipitation-induced subgrade defects from the multiple track inspection data to provide a basis for defect identification. Firstly, the geotechnical site investigation including Ground Penetrating Radar (GPR) detection, moisture content test, and dynamic cone penetration (DCP) test of a typical defective spot is performed to determine the condition of the subgrade after heavy rainfall; then, the analysis methods of track inspection data are introduced; finally, the track geometry data and carbody acceleration data of four typical defective sections are analyzed, and the time-domain, frequency-domain and discrete wavelet transform (DWT)-based features which are highly correlated with the precipitation-induced subgrade defects are extracted. The results show that the feature indexes extracted from track surface irregularity and carbody vertical acceleration increase significantly after heavy rainfall; the long wavelength components (8 m and above) of both track irregularity and carbody vibration are more sensitive to the subgrade defects, which is reflected by the sharp increase of the DWT-based features at some levels corresponding to long wavelength ranges. The results of defect feature extraction based on the track inspection data agree well with the geotechnical site investigation results, which demonstrate the feasibility of utilizing multiple track inspection data to identify the typical precipitation-induced subgrade defects.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-02-16T04:13:07Z
DOI: 10.1177/09544097241234094
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- Investigating the stick-slip vibration behavior of a locomotive with
adhesion control in a curve-
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Authors: Linping Sun, Zhongliang Yang, Weihua Ma, Shihui Luo, Bo Wang
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
In order to explain the wheel-rail stick-slip vibration phenomenon of alocomotive in a curve, a co-simulation dynamic model taking into account adhesion control was established to reproduce the locomotive wheel-rail curve stick-slip vibration behavior, and the effect of parameters such as creep threshold, descent slope, rail surface condition and track curve radius on the stick-slip vibration behavior was measured by the traction force and the overall dispersion of adhesion coefficient. The results illustrate that the wheel-rail curve stick-slip vibration is caused by the dynamic traction force fluctuation under the adhesion control, and the increase of creep threshold will lead to the decrease of tractive force fluctuation amplitude and the decrease of stick-slip vibration intensity, which will increase the adhesion utilization rate, However, the increase of descent slope, the decrease of track curve radius and wheel-rail friction coefficient have the opposite effect on stick-slip vibration behavior. This phenomenon can be eliminated by improving the rail surface condition, expanding the track curve radius and lowering the locomotive traction force.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-02-10T06:49:11Z
DOI: 10.1177/09544097241233039
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- Influence of ballast and railway substructure on the degradation of local
geometry defects-
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Authors: Pedro Rodrigues, Paulo F Teixeira
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
The degradation of track geometry is a very complex phenomenon that has typically been analysed considering global quality indicators. In this paper, the influence of ballast and track substructure on its geometric degradation is analysed by modelling the degradation rates of more than 17,400 local defects of longitudinal levelling, alignment, and twist from 66,892 km of track inspection measurements carried out during the period 2001-2012 on 19 conventional lines of the Portuguese railway network. It is corroborated that singularities markedly contribute to greater density and faster degradation of defects, especially culverts and level crossings. Ballast type and age significantly affect the probability of emergence and degradation rates of defects. In a significant number of situations, defects are found to degrade much faster than the standard deviation indicators, highlighting the importance of monitoring and modelling their evolution to prevent the need for carrying out corrective interventions as much as possible.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-02-08T11:52:52Z
DOI: 10.1177/09544097241232553
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- Non-contact detection method for pantograph-catenary contact force based
on image processing-
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Authors: Chen Hong-ming, Zhou Ning, Cheng Yao, Zhang Wei-hua
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
This paper introduces a non-contact method for detecting contact force between pantograph and catenary (PAC), based on image processing and Kalman filter. A non-contact method for detecting contact force of PAC, which only utilizes the vertical displacement of the collector head, is proposed. First, the images of the collector head area are collected by adding an image acquisition system on the roof of the vehicle. Second, combined with target tracking and template matching, the vertical displacement of the pantograph’s collector head is identified. Finally, based on the Kalman filter considering least squares method and the PAC dynamics model, a method for detecting contact force is constructed. The estimation of the PAC’s dynamic contact force is realized only by using the vertical displacement of the collector head obtained from the image identification. The results of simulation and test-bed results show that the Kalman filter considering least squares significantly has higher accuracy and better robustness compared with the traditional Kalman filter.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-02-07T01:33:47Z
DOI: 10.1177/09544097241230358
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- Characterisation of track buckling resistance
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Authors: Elena Kabo, Anders Ekberg
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
This study sets out with a network-wide analysis of the risk for track buckling that concludes that track buckling relates to a few “weak points” along the track. To identify these, a numerical model to predict track buckling resistance is developed. The influences of key track parameters are evaluated and quantified using the innovative concept of an equivalent temperature. This allows to quantify the large influence of for example, curves and hanging sleepers in terms of an equivalent increase in temperature. Influence of less well-defined track parameters such as nearby fixed points or recent track work is estimated through statistical assessment of track buckling reports. Predicted influence generally agrees with empirical knowledge with some exceptions that are discussed in the report. Developed models and produced results should be valuable in identifying track sections at risk of track buckling and in assessing effectiveness of mitigating actions.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-02-05T06:55:54Z
DOI: 10.1177/09544097241231884
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- Investigation of frictional rolling contact behavior in a switch panel
considering traction load-
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Authors: Yuan Gao, Shuguo Wang, Jingmang Xu
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
The dynamic effects involved in wheel-rail interactions can be increased by the traction force potentially causing rapid degradation of turnout rails. A precise stress/strain analysis is essential for wheel-rail frictional rolling contact and the related degradation. Therefore, an explicit finite element method is established considering dynamic effects related to the contact. Furthermore, the frictional rolling contact solutions and related degradation with different traction coefficient in turnout are investigated. The results indicate that the effect of asymmetric excitation caused by traction force and geometric irregularities will lead to yaw motion of wheelset. The width of running band on the switch rail is increased as the top surface width of the switch rail increases. In addition, the contact patch on the switch rail will gradually shift forward compared to that on the stock rail, leading to excessive shear stress and increase of microslip. Meanwhile, the adhesion-slip distribution, uneven wear and severe plastic deformation during transition are recognized.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-02-05T01:52:26Z
DOI: 10.1177/09544097241232010
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- Automated rerailing of a road-rail shunting vehicle on road-level tracks
using 2D-Lidar-
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Authors: Hyun-Suk Jung, Philipp Niermeyer, Harish Manjunatheswaran, Christian Schindler
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
Road-rail vehicles are emerging increasingly in small flat yards for shunting wagons. While numerous research works suggest automation of the shunting operation to improve its efficiency, the rerailing procedure of such vehicle, i.e., switching between road and rail mode, remains manually executed. Hence, we present a simple but novel method for a road-rail vehicle with skid-steer drive to rerail automatically on road-level tracks (e.g., level-crossing). The vehicle uses two 2D-Lidar sensors to scan the floor for (rail) in order to estimate its lateral displacement and angular orientation towards the track centre. A simplified model and a PID-type controller for the yaw rate were deployed while keeping the linear velocity constant for the vehicle to align itself at the centre of and parallel to the track. Upon reaching the goal, the rail wheels are descended and the rerailing is completed. Test runs were conducted from a random initial pose near the track centre while limiting the travel range in x-direction to 2.5 m, yet allowing a change of direction each time the vehicle reaches this limit. In 97% of the test runs, the vehicle rerailed successfully in 47 s on average (12 s of which was needed for lowering the rail wheels) with three changes of direction or less. In the remaining 3% of cases it took more attempts. Automated rerailing could be used not only as assistance function for the shunting personnel, but also as important feature of an autonomous shunting robot that is able to access both road and rail domains.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-01-23T11:41:53Z
DOI: 10.1177/09544097241229334
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- Influence of thermal loading parameters and microstructure on the
formation of stratified surface layers on railway wheels-
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Authors: Matthias Freisinger, Kurt Pichelbauer, Gerald Trummer, Klaus Six
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
Due to an increasing trend towards environmentally friendly public transport, rail networks face higher speeds and wheel loads affecting the material degradation of the railway components. Within this study, influencing parameters on the formation of stratified surface layers, forming on railway wheels during service due to thermal loadings in the wheel-rail contact, are studied. These layers consist of white etching layer and underlying brown etching layer and are susceptible to fatigue crack initiation. By using laser surface treatments, its formation based on two consecutive thermal loadings is systematically demonstrated on ER7 wheel steel. Further, a decrease in layer thickness with decreasing laser power, and an increase in brown etching layer thickness with increasing laser power difference is shown. Moreover, the effect of finer grain size leading to an increased layer thickness, and the influence of the chemical composition by comparing the standard ER7 wheel steel to a micro-alloyed wheel steel are demonstrated.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-01-23T08:21:19Z
DOI: 10.1177/09544097241229121
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- Impact of coupled effects of airtight components at variable cross-section
location on vehicle airtightness in Wuhan metro-
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Authors: Yang Li, You-mei Liu
Abstract: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Ahead of Print.
To determine the variation in airtightness performance of metro trains under the coupling state of airtight components, a field-based experimental approach was employed to test the air pressure changes during metro train operations. The study analyzed the impact of the coupling effects of the air conditioning pressure wave protection valve, pneumatic auxiliary door lock devices, and passageway drainage plug on the interior pressure changes of the train while operating in challenging environmental conditions. Following industry standards, the assessment evaluated whether the rate of interior pressure change and the train’s dynamic sealing index met the specified requirements. The findings indicate that, with airtight components in an enabled state, the peak-to-peak value of interior pressure change relative to external pressure change decreased by 15% to 39%. Conversely, when airtight components were not enabled, the reduction was only 0% to 25%. Under enabled airtight component conditions, the train’s dynamic sealing index was within the 2-3 s range, whereas in the disabled state, the dynamic sealing index was less than 1 s. The activation of airtight components plays a crucial role in improving train airtightness by significantly reducing the amplitude of interior pressure changes, thereby ensuring both train airtightness and passenger comfort. The results provide valuable insights for the optimization of train design and operation in order to maintain passenger safety and comfort.
Citation: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
PubDate: 2024-01-23T02:49:28Z
DOI: 10.1177/09544097241229120
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