Pub Date : 2023-09-28DOI: 10.1177/09544097231203269
Amin Nazari, Parisa Hosseini-Tehrani
Dynamic modeling of wheel-rail interaction is significant in accurate fatigue analysis of railways. Both location and magnitude of the contact stresses in the contact area must be evaluated accurately and efficiently via computational tools. In curved railway tracks, the distribution of the force exerted on the wheel is complex as it is multiaxial rather than uniaxial; thus, a more comprehensive computational model is required. In this work, a numerical procedure is developed to investigate the fatigue crack initiation on the curved tracks. The Universal Mechanism software is used to specify the spectrum of axial wheel force as input to a three-dimensional explicit finite element model to obtain the resulting stresses at the wheel-rail contact region. A critical element with the maximum von Mises stress value is treated as the element where the fatigue crack is most probably to be initiated. In this element, the critical plane method is used to determine the orientation of the crack initiation. The effect of the radius and slip ratio on the exact site of fatigue crack initiation is established in this approach, and the contact point influence on the fatigue crack initiation parameter is investigated. The proposed model successfully predicts a practical wheel-rail dynamic response to cyclic loading, applying the geometry of the curved track.
{"title":"Using the fatigue crack initiation parameter for prediction of the crack location on a curved track by 3D-FE analysis","authors":"Amin Nazari, Parisa Hosseini-Tehrani","doi":"10.1177/09544097231203269","DOIUrl":"https://doi.org/10.1177/09544097231203269","url":null,"abstract":"Dynamic modeling of wheel-rail interaction is significant in accurate fatigue analysis of railways. Both location and magnitude of the contact stresses in the contact area must be evaluated accurately and efficiently via computational tools. In curved railway tracks, the distribution of the force exerted on the wheel is complex as it is multiaxial rather than uniaxial; thus, a more comprehensive computational model is required. In this work, a numerical procedure is developed to investigate the fatigue crack initiation on the curved tracks. The Universal Mechanism software is used to specify the spectrum of axial wheel force as input to a three-dimensional explicit finite element model to obtain the resulting stresses at the wheel-rail contact region. A critical element with the maximum von Mises stress value is treated as the element where the fatigue crack is most probably to be initiated. In this element, the critical plane method is used to determine the orientation of the crack initiation. The effect of the radius and slip ratio on the exact site of fatigue crack initiation is established in this approach, and the contact point influence on the fatigue crack initiation parameter is investigated. The proposed model successfully predicts a practical wheel-rail dynamic response to cyclic loading, applying the geometry of the curved track.","PeriodicalId":54567,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part F-Journal of Rail and Rapid Transit","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135344347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-21DOI: 10.1177/09544097231203271
Jing He, Duo Qiao, Changfan Zhang
On-time and energy-saving train operation is important for the sustainable development of rail transit. As for the problems of traction energy consumption and on-time arrival at stations faced by trains in rail transit, an optimization strategy of energy-saving speed curves of trains based on an improved adaptive genetic algorithm (AGA) was proposed in this paper. First, weight coefficients of operation time and energy consumption were designed through an analytic hierarchy process, and an optimization model that targets train operation time and energy consumption was established according to a basic train operation model with constraints such as speed limits and precise train stopping. Then, on-time and energy-saving speed curves of trains were generated based on the improved AGA. Finally, a simulation was carried out with actual rail transit lines. The results show that the proposed method has strong efficiency for energy conservation and better optimization performance than the simple genetic algorithm in solving train trajectory optimization problem.
{"title":"On-time and energy-saving train operation strategy based on improved AGA multi-objective optimization","authors":"Jing He, Duo Qiao, Changfan Zhang","doi":"10.1177/09544097231203271","DOIUrl":"https://doi.org/10.1177/09544097231203271","url":null,"abstract":"On-time and energy-saving train operation is important for the sustainable development of rail transit. As for the problems of traction energy consumption and on-time arrival at stations faced by trains in rail transit, an optimization strategy of energy-saving speed curves of trains based on an improved adaptive genetic algorithm (AGA) was proposed in this paper. First, weight coefficients of operation time and energy consumption were designed through an analytic hierarchy process, and an optimization model that targets train operation time and energy consumption was established according to a basic train operation model with constraints such as speed limits and precise train stopping. Then, on-time and energy-saving speed curves of trains were generated based on the improved AGA. Finally, a simulation was carried out with actual rail transit lines. The results show that the proposed method has strong efficiency for energy conservation and better optimization performance than the simple genetic algorithm in solving train trajectory optimization problem.","PeriodicalId":54567,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part F-Journal of Rail and Rapid Transit","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136130437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-14DOI: 10.1177/09544097231201519
Lei Wang, Kai Zhang, Qing Zheng, Guofu Ding, Weihua Zhang, Dejun Chen, Bin Liu
Anomaly detection is essential to ensure metro vehicles' safe operation. Error reconstruction-based anomaly detection methods have been widely studied because they only need to be trained by normal data and do not require much anomaly data, which is challenging to obtain. However, sometimes the auto-encoder network for error reconstructing “generalizes” so well that it also rebuilds the anomaly well, leading to missed anomaly detection. Therefore, this paper proposes an undercarriage image-driven anomaly detection method for metro vehicles based on adversarial memory enhancement. Firstly, this study performs component segmentation based on YOLOv5 detection results and constructs a component anomaly detection dataset. Secondly, an anomaly detection method based on memory enhancement and adversarial training of encoding-decoding-encoding structure is proposed for component anomaly detection. It enables the auto-encoder to reconstruct the image better. Thirdly, the combined indicator of the difference between potential features and reconstruction error is used as an anomaly indicator for anomaly detection of metro components, reducing the rate of fault misses. The experimental results on the established dataset demonstrate that the proposed method reduces false negative rates of 92.4%, 92.6%, 74.6%, and 59.1% compared with [Formula: see text], [Formula: see text], GANomaly, and MemAE, respectively.
异常检测是保障地铁车辆安全运行的关键。基于误差重构的异常检测方法由于只需要正常数据训练，不需要大量异常数据，因而得到了广泛的研究。然而，有时用于错误重建的自编码器网络“泛化”得太好，以至于它也很好地重建了异常，从而导致错过异常检测。为此，本文提出了一种基于对抗记忆增强的地铁车辆底盘图像驱动异常检测方法。首先，本研究基于YOLOv5检测结果进行组件分割，构建组件异常检测数据集。其次，提出了一种基于记忆增强和编码-解码-编码结构对抗训练的构件异常检测方法。它使自动编码器能够更好地重建图像。再次，将潜在特征差与重构误差的组合指标作为城域构件异常检测的异常指标，降低了故障漏检率。在已建立的数据集上的实验结果表明，与[Formula: see text]、[Formula: see text]、GANomaly和MemAE相比，本文方法的假阴性率分别降低了92.4%、92.6%、74.6%和59.1%。
{"title":"An undercarriage image driven anomaly detection method for metro vehicle based on adversarial memory enhancement","authors":"Lei Wang, Kai Zhang, Qing Zheng, Guofu Ding, Weihua Zhang, Dejun Chen, Bin Liu","doi":"10.1177/09544097231201519","DOIUrl":"https://doi.org/10.1177/09544097231201519","url":null,"abstract":"Anomaly detection is essential to ensure metro vehicles' safe operation. Error reconstruction-based anomaly detection methods have been widely studied because they only need to be trained by normal data and do not require much anomaly data, which is challenging to obtain. However, sometimes the auto-encoder network for error reconstructing “generalizes” so well that it also rebuilds the anomaly well, leading to missed anomaly detection. Therefore, this paper proposes an undercarriage image-driven anomaly detection method for metro vehicles based on adversarial memory enhancement. Firstly, this study performs component segmentation based on YOLOv5 detection results and constructs a component anomaly detection dataset. Secondly, an anomaly detection method based on memory enhancement and adversarial training of encoding-decoding-encoding structure is proposed for component anomaly detection. It enables the auto-encoder to reconstruct the image better. Thirdly, the combined indicator of the difference between potential features and reconstruction error is used as an anomaly indicator for anomaly detection of metro components, reducing the rate of fault misses. The experimental results on the established dataset demonstrate that the proposed method reduces false negative rates of 92.4%, 92.6%, 74.6%, and 59.1% compared with [Formula: see text], [Formula: see text], GANomaly, and MemAE, respectively.","PeriodicalId":54567,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part F-Journal of Rail and Rapid Transit","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134970873","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-14DOI: 10.1177/09544097231201513
I. La Paglia, E. Di Gialleonardo, A. Facchinetti, M. Carnevale, R. Corradi
In this paper, a condition monitoring system for railway track geometry is presented. The methodology has been designed for high-speed application, where the train travels at the maximum allowed speed for most of the trip. The system is designed to rely on acceleration data recorded by in-service vehicles to provide estimations of the track longitudinal level, based on pre-built regression models. It exploits synthetic indicators sampled over predefined track sections 100 m long. Different predictors are considered, computed both from acceleration data and from track geometry measured by the diagnostic train. The proposed modelling strategy allows distinguishing between isolated and distributed defects that populate the railway track as well as reproducing the evolution over time of the maximum longitudinal level registered in the considered track section; moreover, also accurate predictions of the defect amplitude are made. The results have been validated against track geometry data recorded by the diagnostic train during a monitoring period of 2 years. It is proven that the proposed system could support current maintenance strategies, providing a continuous flow of data to monitor the track infrastructure.
{"title":"Acceleration-based condition monitoring of track longitudinal level using multiple regression models","authors":"I. La Paglia, E. Di Gialleonardo, A. Facchinetti, M. Carnevale, R. Corradi","doi":"10.1177/09544097231201513","DOIUrl":"https://doi.org/10.1177/09544097231201513","url":null,"abstract":"In this paper, a condition monitoring system for railway track geometry is presented. The methodology has been designed for high-speed application, where the train travels at the maximum allowed speed for most of the trip. The system is designed to rely on acceleration data recorded by in-service vehicles to provide estimations of the track longitudinal level, based on pre-built regression models. It exploits synthetic indicators sampled over predefined track sections 100 m long. Different predictors are considered, computed both from acceleration data and from track geometry measured by the diagnostic train. The proposed modelling strategy allows distinguishing between isolated and distributed defects that populate the railway track as well as reproducing the evolution over time of the maximum longitudinal level registered in the considered track section; moreover, also accurate predictions of the defect amplitude are made. The results have been validated against track geometry data recorded by the diagnostic train during a monitoring period of 2 years. It is proven that the proposed system could support current maintenance strategies, providing a continuous flow of data to monitor the track infrastructure.","PeriodicalId":54567,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part F-Journal of Rail and Rapid Transit","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134911419","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-13DOI: 10.1177/09544097231201928
Yang Liangliang, Huang Xiaocui, Fu Maohai, Luo Shihui, Zeng Wenchang
A friction draft gear model was developed to assess the degraded dynamic characteristics of worn draft gears in the vehicle impact condition. It presents an approach to simulate multiple typical wear profiles of wedge shoes and reflect their effects on the draft gear performance. Based on the rated design indexes and existing overhaul regulations of MT-2 type friction draft gears in China, the safety wear limits for wedge shoes with different wear profiles were classified and assessed. The results indicate that wedge shoes with uniform or concave wear can significantly worsen draft gear performance, and the existing maintenance limit of 1 mm only applies to wedge shoes with uniform wear but not to the most common wedge shoes with concave wear. Also, for wedge shoes with concave wear, when the wear area covers 50%, 75%, and 100% of the total main friction surface, the corresponding safety wear limits are 0.5 mm, 0.8 mm, and 1.3 mm, respectively. Therefore, it is proposed to design multiple graded and dynamic maintenance limits to ensure the service safety of MT-2 type friction draft gears.
{"title":"Assessing dynamic characteristics for friction draft gears with worn wedge shoes","authors":"Yang Liangliang, Huang Xiaocui, Fu Maohai, Luo Shihui, Zeng Wenchang","doi":"10.1177/09544097231201928","DOIUrl":"https://doi.org/10.1177/09544097231201928","url":null,"abstract":"A friction draft gear model was developed to assess the degraded dynamic characteristics of worn draft gears in the vehicle impact condition. It presents an approach to simulate multiple typical wear profiles of wedge shoes and reflect their effects on the draft gear performance. Based on the rated design indexes and existing overhaul regulations of MT-2 type friction draft gears in China, the safety wear limits for wedge shoes with different wear profiles were classified and assessed. The results indicate that wedge shoes with uniform or concave wear can significantly worsen draft gear performance, and the existing maintenance limit of 1 mm only applies to wedge shoes with uniform wear but not to the most common wedge shoes with concave wear. Also, for wedge shoes with concave wear, when the wear area covers 50%, 75%, and 100% of the total main friction surface, the corresponding safety wear limits are 0.5 mm, 0.8 mm, and 1.3 mm, respectively. Therefore, it is proposed to design multiple graded and dynamic maintenance limits to ensure the service safety of MT-2 type friction draft gears.","PeriodicalId":54567,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part F-Journal of Rail and Rapid Transit","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135691163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-01DOI: 10.1177/09544097231192716
Jingcheng Wen, Qi Li, Zhenggang Lu
Owing to the blunt car body and high design speed of express freight trains, the running safety is significantly affected by crosswinds when the train runs over a bridge; moreover, severe accidents, such as derailment or overturning may occur. Therefore, adequate measures should be adopted to avoid the occurrence of such accidents. In this study, a finite element model of the train, ballastless track, and parameterized 5-span simply supported girder bridge along with modal superposition method are adopted to establish the train-track-bridge coupling dynamic system. Numerical simulation of stochastic wind speed, wind tunnel tests, and computational fluid dynamics (CFD) simulation of vehicle-bridge scale model were conducted to calculate the wind load acting on the train and bridge. The dynamic responses of the bridge and train were evaluated to present the diagrams of wind and train speed limits for safe operation. The results indicated that the running safety of the vehicle declined with the wind and train speeds, and the wheel unloading rate was the most sensitive to wind speed. For safe operation, the train speed must be restricted if the mean wind speed is greater than 22.7 m/s, and an extreme scenario of derailment may occur for a mean wind speed of 34.0 m/s. In addition, the wind speed limit should be appropriately adjusted and improved according to the pier height of the bridge and terrain category. This research provides a theoretical basis and data support for the assessment of safety of express freight trains in actual operation.
{"title":"Safety of an express freight train running over a bridge in crosswind","authors":"Jingcheng Wen, Qi Li, Zhenggang Lu","doi":"10.1177/09544097231192716","DOIUrl":"https://doi.org/10.1177/09544097231192716","url":null,"abstract":"Owing to the blunt car body and high design speed of express freight trains, the running safety is significantly affected by crosswinds when the train runs over a bridge; moreover, severe accidents, such as derailment or overturning may occur. Therefore, adequate measures should be adopted to avoid the occurrence of such accidents. In this study, a finite element model of the train, ballastless track, and parameterized 5-span simply supported girder bridge along with modal superposition method are adopted to establish the train-track-bridge coupling dynamic system. Numerical simulation of stochastic wind speed, wind tunnel tests, and computational fluid dynamics (CFD) simulation of vehicle-bridge scale model were conducted to calculate the wind load acting on the train and bridge. The dynamic responses of the bridge and train were evaluated to present the diagrams of wind and train speed limits for safe operation. The results indicated that the running safety of the vehicle declined with the wind and train speeds, and the wheel unloading rate was the most sensitive to wind speed. For safe operation, the train speed must be restricted if the mean wind speed is greater than 22.7 m/s, and an extreme scenario of derailment may occur for a mean wind speed of 34.0 m/s. In addition, the wind speed limit should be appropriately adjusted and improved according to the pier height of the bridge and terrain category. This research provides a theoretical basis and data support for the assessment of safety of express freight trains in actual operation.","PeriodicalId":54567,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part F-Journal of Rail and Rapid Transit","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84655574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-25DOI: 10.1177/09544097231195917
Zhenning Yang, Lai Wei, Feng Gan, Dadi Li, H. Dai
During the operation of the Chinese 250 km/h-level EMU, hunting occurs when the EMU crosses from Line B to Line A. Numerous tests and simulations have been conducted to investigate the mechanism of this phenomenon. Comparisons of the measured rail profiles of the two lines indicate that the left rail in Line A is higher than that in Line B at the inner rail shoulder. In addition, the top position of the right rail in Line A is approximately 2–3 mm closer to the inside than that of the right rail in Line B, with the right rail in Line A being higher than that in Line B at the inner rail shoulder. These differences cause a significant increase in the wheel–rail equivalent conicity when the EMU crosses from Line B to Line A and further cause the hunting phenomenon. Moreover, simulations and experiments are conducted to investigate the countermeasures for EMU cross-line hunting. Field test results show that both increasing the damping of the yaw damper and wheel reprofiling can improve the stability during EMU cross-line operation; however, the effect of increasing the damping of the yaw damper is limited under particularly poor wheel–rail relationship. Simulation results reveal that rail grinding of Line A referring to the Chinese 60N rail profile can also improve the stability of the EMU during cross-line operation.
{"title":"Hunting motion of high-speed emu during cross-line operation: Mechanism and countermeasures","authors":"Zhenning Yang, Lai Wei, Feng Gan, Dadi Li, H. Dai","doi":"10.1177/09544097231195917","DOIUrl":"https://doi.org/10.1177/09544097231195917","url":null,"abstract":"During the operation of the Chinese 250 km/h-level EMU, hunting occurs when the EMU crosses from Line B to Line A. Numerous tests and simulations have been conducted to investigate the mechanism of this phenomenon. Comparisons of the measured rail profiles of the two lines indicate that the left rail in Line A is higher than that in Line B at the inner rail shoulder. In addition, the top position of the right rail in Line A is approximately 2–3 mm closer to the inside than that of the right rail in Line B, with the right rail in Line A being higher than that in Line B at the inner rail shoulder. These differences cause a significant increase in the wheel–rail equivalent conicity when the EMU crosses from Line B to Line A and further cause the hunting phenomenon. Moreover, simulations and experiments are conducted to investigate the countermeasures for EMU cross-line hunting. Field test results show that both increasing the damping of the yaw damper and wheel reprofiling can improve the stability during EMU cross-line operation; however, the effect of increasing the damping of the yaw damper is limited under particularly poor wheel–rail relationship. Simulation results reveal that rail grinding of Line A referring to the Chinese 60N rail profile can also improve the stability of the EMU during cross-line operation.","PeriodicalId":54567,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part F-Journal of Rail and Rapid Transit","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84414234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To consider the coupled effect on the running safety between elastic track and longitudinal impulse of Long Heavy Haul Train(LHHT), a train/track coupled dynamics model is established by using connection substructure theory. The ballasted track is divided into several segments called sub-tracks: a sub-track includes rail, sleepers and ballast. In the sub-track model, the sleepers and ballast are modelled as lumped mass. The rail is divided into the contact and connection rail. The contact rail is modelled as an Euler beam to reflect the wheel/rail interaction and the flexible vibration of the rail. The connection rail is modelled as a super element to reflect the interaction between adjacent contact rail. To increase the simulation speed, a new parallel computing method is proposed: a train/track coupled dynamics model is divided into different submodule, a submodule includes a sub-track and a vehicle on the sub-track. A submodule is calculated by a single computer core. The submodule is connected by connection rail, couplers and ballast. The advantage of this parallel method is that the load of each computer core is almost uniform. The simulation speed depends on the number of parallel computing cores instead of one core with a particularly large load. Finally, taking the 10,000-ton train as an example, the distribution of coupler force, the derailment coefficient and wheel unloading rate are given during the train braking on a curve, which shows the application and necessity of the train/track coupled dynamics model based on substructure and parallel computing.
{"title":"Train/track coupled dynamics model of long heavy haul train based on substructure and parallel computing","authors":"Qi Wang, X. Xiao, Jia-Nuo Wang, Wei Wang, Yezhou Yang, X. Jin","doi":"10.1177/09544097231196338","DOIUrl":"https://doi.org/10.1177/09544097231196338","url":null,"abstract":"To consider the coupled effect on the running safety between elastic track and longitudinal impulse of Long Heavy Haul Train(LHHT), a train/track coupled dynamics model is established by using connection substructure theory. The ballasted track is divided into several segments called sub-tracks: a sub-track includes rail, sleepers and ballast. In the sub-track model, the sleepers and ballast are modelled as lumped mass. The rail is divided into the contact and connection rail. The contact rail is modelled as an Euler beam to reflect the wheel/rail interaction and the flexible vibration of the rail. The connection rail is modelled as a super element to reflect the interaction between adjacent contact rail. To increase the simulation speed, a new parallel computing method is proposed: a train/track coupled dynamics model is divided into different submodule, a submodule includes a sub-track and a vehicle on the sub-track. A submodule is calculated by a single computer core. The submodule is connected by connection rail, couplers and ballast. The advantage of this parallel method is that the load of each computer core is almost uniform. The simulation speed depends on the number of parallel computing cores instead of one core with a particularly large load. Finally, taking the 10,000-ton train as an example, the distribution of coupler force, the derailment coefficient and wheel unloading rate are given during the train braking on a curve, which shows the application and necessity of the train/track coupled dynamics model based on substructure and parallel computing.","PeriodicalId":54567,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part F-Journal of Rail and Rapid Transit","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79704737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-18DOI: 10.1177/09544097231196286
Qun Ma, Yuan Yao, Fanyu Meng, Wei Wei
This paper takes 30,000-ton heavy-haul trains as the research object, and studies the propagation characteristics, train braking ability and longitudinal impulse level of three ECP electronic control signal Propagation modes of segmented electro-pneumatic braking under different lag times. The difference between the train’s use of segmented electro-pneumatic braking and air braking in the long ramp operation method is compared. The results show that the best way is when the leading control locomotive sends the ECP signal backward and the slave control locomotive sends the ECP signal both forward and backward. Compared with the worst mode that only the leading control locomotive propagates the ECP signal backward, the coupler force can be reduced by 46.5%, the time difference between the slowest and fastest action vehicles can be reduced by 60.5%, and the emergency braking distance can be reduced by 1.2%. With the increase in the lag time of the slave control locomotive, the differences in the braking capacity and longitudinal impulse level of the three ECP electronic control signal propagation modes decrease. The effectiveness of the slave control locomotive’s ability to send ECP signals is closely related to the lag time of the leading and slave control locomotives. Compared with pure air braking, segmented electro-pneumatic braking can delay the braking times of the last two brakes by 32.6 s and 83.7 s,respectively, during the three-cycle braking, and the starting time of relief can be delayed by 12.7 s, 89.8 s and 16.9 s respectively, and the maximum coupler force can be reduced by 30.1%. The research work of this paper can provide reference for the formulation of electro-pneumatic braking scheme of 30,000-tons heavy-haul train.
{"title":"The design of electronically controlled pneumatic brake signal propagation mode for electronic control braking of a 30,000-ton heavy-haul train","authors":"Qun Ma, Yuan Yao, Fanyu Meng, Wei Wei","doi":"10.1177/09544097231196286","DOIUrl":"https://doi.org/10.1177/09544097231196286","url":null,"abstract":"This paper takes 30,000-ton heavy-haul trains as the research object, and studies the propagation characteristics, train braking ability and longitudinal impulse level of three ECP electronic control signal Propagation modes of segmented electro-pneumatic braking under different lag times. The difference between the train’s use of segmented electro-pneumatic braking and air braking in the long ramp operation method is compared. The results show that the best way is when the leading control locomotive sends the ECP signal backward and the slave control locomotive sends the ECP signal both forward and backward. Compared with the worst mode that only the leading control locomotive propagates the ECP signal backward, the coupler force can be reduced by 46.5%, the time difference between the slowest and fastest action vehicles can be reduced by 60.5%, and the emergency braking distance can be reduced by 1.2%. With the increase in the lag time of the slave control locomotive, the differences in the braking capacity and longitudinal impulse level of the three ECP electronic control signal propagation modes decrease. The effectiveness of the slave control locomotive’s ability to send ECP signals is closely related to the lag time of the leading and slave control locomotives. Compared with pure air braking, segmented electro-pneumatic braking can delay the braking times of the last two brakes by 32.6 s and 83.7 s,respectively, during the three-cycle braking, and the starting time of relief can be delayed by 12.7 s, 89.8 s and 16.9 s respectively, and the maximum coupler force can be reduced by 30.1%. The research work of this paper can provide reference for the formulation of electro-pneumatic braking scheme of 30,000-tons heavy-haul train.","PeriodicalId":54567,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part F-Journal of Rail and Rapid Transit","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84363783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-03DOI: 10.1177/09544097231193274
Shenghua Wang, Bingguang Wen, Dexiang Ren, Yaqi Ding, Z. Wen, Dawei Dong, G. Tao
Two of the Shanghai metro lines suffered from severe side wear on the high rail, not only in sharp curves but also in large curves, and the service life of some rails on sharp curves was reduced by approximately 50% compared with the last rail replacement. Features and evolution rules for the rail side wear and the wheel flange wear were determined by field measurements and long-term monitoring. A rail wear prediction model, verified in our previous work, is used to reveal the influence of factors on rail wear. The results indicate that the poor lubrication condition at the rail gauge face is the main cause of severe side wear of the high rail, and the use of wheel profiles with low conicity and the loss of profile curvature of low rail profiles caused by the untimely maintenance also increase the side wear of the high rail. The service life of the high rail could be greatly extended by some countermeasures, such as repairing the worn shape of the low rail and repairing/improving the wayside lubrication system.
{"title":"Analysis of the causes of severe side wear of the high rail on metro curves by numerical simulation and field investigation","authors":"Shenghua Wang, Bingguang Wen, Dexiang Ren, Yaqi Ding, Z. Wen, Dawei Dong, G. Tao","doi":"10.1177/09544097231193274","DOIUrl":"https://doi.org/10.1177/09544097231193274","url":null,"abstract":"Two of the Shanghai metro lines suffered from severe side wear on the high rail, not only in sharp curves but also in large curves, and the service life of some rails on sharp curves was reduced by approximately 50% compared with the last rail replacement. Features and evolution rules for the rail side wear and the wheel flange wear were determined by field measurements and long-term monitoring. A rail wear prediction model, verified in our previous work, is used to reveal the influence of factors on rail wear. The results indicate that the poor lubrication condition at the rail gauge face is the main cause of severe side wear of the high rail, and the use of wheel profiles with low conicity and the loss of profile curvature of low rail profiles caused by the untimely maintenance also increase the side wear of the high rail. The service life of the high rail could be greatly extended by some countermeasures, such as repairing the worn shape of the low rail and repairing/improving the wayside lubrication system.","PeriodicalId":54567,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part F-Journal of Rail and Rapid Transit","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86413536","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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