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.
{"title":"Nonlinear impedance characteristics of a gas hydraulic energy absorber and performance prediction for railway transportation of valuable goods","authors":"Wenlin Wang, Hongyou Liu, Dazhuo Wu, Yongming Wu, Jian Zhao","doi":"10.1177/09544097241249504","DOIUrl":"https://doi.org/10.1177/09544097241249504","url":null,"abstract":"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.","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":"2024-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140842296","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 : 2024-04-03DOI: 10.1177/09544097241244411
Yan Quan Sun, Maksym Spiryagin, Qing Wu, Colin Cole
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.
研究了弯曲轨道上的润滑剂对重型机车轮轨接触磨损的影响。为了分析现有高粘性交流机车造成的轮轨接触磨损损坏，提出了一种研究方法，要求机车模型在最大牵引力下以 20 km/h 的速度运行，模拟还包括直流机车以进行比较。由 Polach 开发的扩展蠕变力模型已被广泛用于摩擦系数可变的干湿条件下的轮轨接触，该模型被进一步扩展以适用于典型的低摩擦系数改性剂、油和润滑脂润滑条件。使用两对轮轨材料的磨损模型来预测磨损率，并给出磨损数字 Tγ 供讨论。模拟结果表明，润滑剂可显著降低轮轨接触磨损。
{"title":"Wheel-rail contact wear analysis on curved lubricated track for heavy haul locomotive studies","authors":"Yan Quan Sun, Maksym Spiryagin, Qing Wu, Colin Cole","doi":"10.1177/09544097241244411","DOIUrl":"https://doi.org/10.1177/09544097241244411","url":null,"abstract":"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.","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":"2024-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140581400","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 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.
{"title":"Force transmission and height adjustment stability of the new height adjustable long pillow ballastless track","authors":"Zhenxing He, Cheng Luo, Shuzhen Wang, Jianfeng Yun, Quanbao Feng","doi":"10.1177/09544097241241418","DOIUrl":"https://doi.org/10.1177/09544097241241418","url":null,"abstract":"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.","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":"2024-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140324414","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 : 2024-03-27DOI: 10.1177/09544097231226148
Lee Pardoe, William Powrie, Zhiwei Hu
The paper assesses the effect on the air flow regime underneath a simplified high-speed train of changing the ballast depth and the sleeper shape, with regard to its potential for causing ballast flight or pickup. The study was carried out numerically using the commercial Computational Fluid Dynamics (CFD) software AnSys Fluent. The flow profile beneath the underbody of the train was generated by means of a moving wall above the track. The Delayed Detached Eddy Simulation (DDES) with the SST [Formula: see text] turbulence model was used to simulate turbulent flow, and the ballast bed roughness was applied parametrically using the wall roughness feature when resolving the boundary layer. CFD simulations were validated for flow over a cube, showing good agreement with experimental results. Up to three different depths to the ballast surface and three different sleeper profiles were investigated. Velocity profiles and aerodynamic forces on cubes placed between or on top of the sleeper blocks were used to assess the propensity of individual ballast grains for movement. For a standard G44 sleeper, increasing the ballast depth and/or the ballast bed roughness was found to reduce aerodynamic loads on an individual ballast grain. A ballast grain on top of the sleeper is more prone to uplift than a grain on the surface of the ballast bed in the crib. A curved upper surface to the sleeper is beneficial in that it prevents ballast from settling on top, the most vulnerable position. However, the reduced flow separation associated with the curved top may increase the likelihood of ballast pickup from the crib. Hence new sleeper shapes intended to reduce the potential for ballast flight should not only prevent ballast from settling on top, but also increase flow separation through the provision of a sharp surface. A prismatic sleeper shape that achieves both is suggested.
{"title":"A computational fluid dynamics study of the influence of sleeper shape and ballast depth on ballast flight during passage of a simplified train","authors":"Lee Pardoe, William Powrie, Zhiwei Hu","doi":"10.1177/09544097231226148","DOIUrl":"https://doi.org/10.1177/09544097231226148","url":null,"abstract":"The paper assesses the effect on the air flow regime underneath a simplified high-speed train of changing the ballast depth and the sleeper shape, with regard to its potential for causing ballast flight or pickup. The study was carried out numerically using the commercial Computational Fluid Dynamics (CFD) software AnSys Fluent. The flow profile beneath the underbody of the train was generated by means of a moving wall above the track. The Delayed Detached Eddy Simulation (DDES) with the SST [Formula: see text] turbulence model was used to simulate turbulent flow, and the ballast bed roughness was applied parametrically using the wall roughness feature when resolving the boundary layer. CFD simulations were validated for flow over a cube, showing good agreement with experimental results. Up to three different depths to the ballast surface and three different sleeper profiles were investigated. Velocity profiles and aerodynamic forces on cubes placed between or on top of the sleeper blocks were used to assess the propensity of individual ballast grains for movement. For a standard G44 sleeper, increasing the ballast depth and/or the ballast bed roughness was found to reduce aerodynamic loads on an individual ballast grain. A ballast grain on top of the sleeper is more prone to uplift than a grain on the surface of the ballast bed in the crib. A curved upper surface to the sleeper is beneficial in that it prevents ballast from settling on top, the most vulnerable position. However, the reduced flow separation associated with the curved top may increase the likelihood of ballast pickup from the crib. Hence new sleeper shapes intended to reduce the potential for ballast flight should not only prevent ballast from settling on top, but also increase flow separation through the provision of a sharp surface. A prismatic sleeper shape that achieves both is suggested.","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":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140316000","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 : 2024-03-26DOI: 10.1177/09544097241242169
Adam PG Wilby, Jacob Corteen, Roger Lewis, David I Fletcher
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.
我们开发了一种新的光学监测系统，用于实时现场拍摄正在进行磨损测试的钢轨双圆盘试样运行表面的损伤起始点。线扫描摄像系统已在谢菲尔德大学 ROlling Sliding 2 (SUROS2) 双盘机上进行了演示。结果表明，该系统可以连续跟踪磨损片的发展，首次在不中断测试的情况下观察到磨损片的开始和磨损片尺寸的稳定。量化总磨损片阴影像素数的图像分析表明与质量损失结果有很好的相关性，这表明光学数据具有在不中断测试的情况下量化钢轨磨损的潜力。此外，在水润滑测试中，新系统还能通过试样上的水层观察滚动接触疲劳（RCF）裂纹的产生，而无需中断测试。通过新的观察方法，对钢轨磨损和 RCF 性能的了解不断加深，有助于提高对钢轨性能的认识，并有助于根据钢轨性能选择钢轨等级。
{"title":"Novel in-situ real-time line scan optical monitoring of wear and surface damage initiation in a laboratory twin disc test","authors":"Adam PG Wilby, Jacob Corteen, Roger Lewis, David I Fletcher","doi":"10.1177/09544097241242169","DOIUrl":"https://doi.org/10.1177/09544097241242169","url":null,"abstract":"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.","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":"2024-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140315915","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 : 2024-03-21DOI: 10.1177/09544097241241102
Jacob W Whittle, Stephen Danks, Iwo Słodczyk, David I Fletcher
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.
{"title":"Using digital image correlation (DIC) to measure railway ballast movement in full-scale laboratory testing of sleeper lateral resistance","authors":"Jacob W Whittle, Stephen Danks, Iwo Słodczyk, David I Fletcher","doi":"10.1177/09544097241241102","DOIUrl":"https://doi.org/10.1177/09544097241241102","url":null,"abstract":"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.","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":"2024-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140205448","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 : 2024-03-09DOI: 10.1177/09544097241239089
Gengzhuo Miao, Ren Luo, Huailong Shi
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.
{"title":"Wheel wear prediction for high-speed trains by considering wheel-rail elastic deformation","authors":"Gengzhuo Miao, Ren Luo, Huailong Shi","doi":"10.1177/09544097241239089","DOIUrl":"https://doi.org/10.1177/09544097241239089","url":null,"abstract":"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.","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":"2024-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140127236","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 : 2024-02-27DOI: 10.1177/09544097241229142
Maorui Hou, Yayun Qi, Changxin Chi, Peng Ao, Hua Liu
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.
{"title":"Wheel profile optimization for intercity EMUs based on the Gaussian function correction method","authors":"Maorui Hou, Yayun Qi, Changxin Chi, Peng Ao, Hua Liu","doi":"10.1177/09544097241229142","DOIUrl":"https://doi.org/10.1177/09544097241229142","url":null,"abstract":"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.","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":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140001973","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 : 2024-02-26DOI: 10.1177/09544097241234959
Luca Pugi, Luca di Carlo
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.
{"title":"Multi-modal battery-operated trains on partially electrified lines: A case study on some regional lines in Italy","authors":"Luca Pugi, Luca di Carlo","doi":"10.1177/09544097241234959","DOIUrl":"https://doi.org/10.1177/09544097241234959","url":null,"abstract":"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.","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":"2024-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139979570","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 : 2024-02-19DOI: 10.1177/09544097241234704
Zhihui Zhu, Yongjiu Tang, Weiqi Zheng, Yu Qin, Lei Yu, Xiang Wang
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.
本文研究了沉降对力、轨道变形和列车动力学的影响，以确定无砟轨道混凝土箱形路基（BTCBS）的沉降阈值。首先，本研究介绍了四种沉降类型，即 V 形沉降、箱形滚动沉降、箱形断层沉降和梯形沉降。建立了 BTCBS 的非线性有限元模型（FEM）和考虑轨道板与底板非线性接触的列车无砟轨道混凝土箱形路基（TBTCBS）模型。然后，研究了沉降对扣件力、轨道变形和车辆动力学的影响。根据计算结果和中国规范，可以得出 BTCBS 的沉降限值。结果表明，箱形滚动和断层的沉降限值受扣件垂直力控制，V 形和梯形沉降的沉降限值受 10 米弦向垂直不规则线（CVVI）控制。建议的 BTCBS 箱形断层、箱形滚动、梯形和 V 形沉降的沉降限值分别为 2.48 毫米、2.55 毫米、17.43 毫米和 8.79 毫米。
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