| 1. |
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| 2. |
- Song, Yang, et al.
(författare)
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Contact Wire Irregularity Stochastics and Effect on High-Speed Railway Pantograph-Catenary Interactions
- 2020
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0018-9456 .- 1557-9662. ; 69:10, s. 8196-8206
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Tidskriftsartikel (refereegranskat)abstract
- In high-speed rail operations, contact wire irregularity (CWI) in a catenary is a common disturbance to the pantograph-catenary interaction performance, which directly affects the quality of current collection. To describe the pointwise stochastics of CWI, the power spectral density (PSD) function for CWI is proposed, and its effect on the pantograph-catenary interaction is investigated. First, a preprocessing procedure is proposed to eliminate the redundant information in the measured irregularities based on the ensemble empirical mode decomposition (EEMD). Then, the upper envelope of the irregularity, which contains all the information regarding the dropper positions on the contact wire, is extracted. A form of the PSD function is suggested for contact wire irregularities. A methodology is proposed to include the effect of random irregularities in the assessment of the interaction performance of a pantograph-catenary. A developed target configuration under dead load (TCUD) method is used to calculate the initial configuration of the catenary, in which the dropper points on the contact wire are placed on their exact positions. Finally, the effect of the random contact wire irregularities on the contact force is investigated through 500 numerical simulations at each operating speed. The present results indicate that random irregularities have a direct impact on the pantograph-catenary contact, including an increment in the dispersion of the contact force statistics. The stochastic analysis shows that over 70% of the results with irregularities are worse than the ideal result without irregularities.
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| 3. |
- Wang, Jintian, et al.
(författare)
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An experimental study on abnormal vibration of metro trains caused by out-of-round wheels
- 2023
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Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - : SAGE Publications. - 0954-4097 .- 2041-3017. ; 237:2, s. 224-231
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Tidskriftsartikel (refereegranskat)abstract
- Out-of-round (OOR) wheel often happens to trains, which can cause abnormal vibration. To develop effective countermeasures to minimize the abnormal vibration, it is necessary to study how the wheel OOR wear affects the vehicle vibration. This paper performs an experimental study on the abnormal vibration characteristics of metro trains with out-of-round wheels. The vibration characteristics is identified by the general survey of wheel roughness from special tests. The statistic wheel wear values of all the vehicles in an operating metro lines are studied to investigate the relationship between the wheel wear and the operating mileage. Several re-profiling strategies are implemented to eliminate the abnormal vibration caused by wheel OOR. The results show that the root cause of the abnormal vibration and deterioration of ride comfort is the car-body flexible resonance excited by the wheel OOR wear. Wheel re-profiling is the most effective measure for reducing the vehicle abnormal vibration. By re-profiling all the wheels of a tested metro vehicle, the ride comfort can be improved by 35% ∼ 40% and the axle-box acceleration can be reduced by 40%.
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| 4. |
- Xu, Yan, et al.
(författare)
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Reduced-order modeling of train-curved-slab-track dynamics with the effects of fastening failures
- 2022
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Ingår i: Acta Mechanica Sinica. - : Springer Nature. - 0567-7718 .- 0459-1879 .- 1614-3116. ; 38
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Tidskriftsartikel (refereegranskat)abstract
- Fastening failures have frequently been found on China high-speed railway curved tracks in recent years. Thus the influence of fastening failures on high-speed train-track interaction in curved track needs to be analyzed. A train-curved slab track interaction model is built, in which the real shape of the curved rail is considered and modeled with reduced beam model (RBM) and curved beam theory, and the slabs are modeled with four-nodes Kirchhoff-Love plate elements. The present model is validated at first with different traditional models. Then the influence of fastening failure in curved slab track on train-track interaction dynamics is studied. A different number of failed fastenings is assumed to occur at the curved track, and different types of fastening failure including the fatigue fracture of the clip structure and failure of the rail pad are considered. Based on the calculation results, the fatigue fracture of the clip structure has little influence on train-track interaction dynamics. But when rail pad failure happens and its equivalent vertical stiffness and damping are less than one-tenth of its original, the fastening failure seriously affects the high-speed train operation safety, and it must be prevented
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| 5. |
- Ding, X., et al.
(författare)
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Monitoring and analysis of dynamic behaviour of high-speed trains in long-term service using an unattended test system
- 2019
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Ingår i: International Journal of COMADEM. - : COMADEM International. - 1363-7681. ; 22:3, s. 45-50
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Tidskriftsartikel (refereegranskat)abstract
- Dynamic behaviour and its evolution are concerns for those operating high-speed trains. In this paper, a cloud server is applied to establish a connection between the vehicle-mounted equipment and users to decrease the influence of network instability. To ensure the accuracy and consistency of data transmission, MQTT (Message Queue Telemetry Transport) protocol is used to transfer data measured from the vehicle. The paper discovers the vibration transfer characteristic and the evolution of the dynamic behaviour of several types of high-speed trains, along with wheel wear under several operation conditions, over time. The turbulence caused by high-order wheel polygonalization formed during long-term service, which cannot be weakened by the suspended system sufficiently, is harmful to the ride quality of high-speed trains. The results confirm the operational reliability of the high-speed trains in China and provide useful references for the optimisation and maintenance of high-speed trains.
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| 6. |
- Lei, Lei, et al.
(författare)
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Displacement Identification by Computer Vision for ConditionMonitoring of Rail Vehicle Bearings
- 2021
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Ingår i: Sensors. - : MDPI. - 1424-8220. ; 21:6
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Tidskriftsartikel (refereegranskat)abstract
- Bearings of rail vehicles bear various dynamic forces. Any fault of the bearing seriouslythreatens running safety. For fault diagnosis, vibration and temperature measured from the bogieand acoustic signals measured from trackside are often used. However, installing additional sensingdevices on the bogie increases manufacturing cost while trackside monitoring is susceptible toambient noise. For other application, structural displacement based on computer vision is widelyapplied for deflection measurement and damage identification of bridges. This article proposesto monitor the health condition of the rail vehicle bearings by detecting the displacement of boltson the end cap of the bearing box. This study is performed based on an experimental platform ofbearing systems. The displacement is monitored by computer vision, which can image real-timedisplacement of the bolts. The health condition of bearings is reflected by the amplitude of thedetected displacement by phase correlation method which is separately studied by simulation. Toimprove the calculation rate, the computer vision only locally focuses on three bolts rather thanthe whole image. The displacement amplitudes of the bearing system in the vertical direction arederived by comparing the correlations of the image’s gray-level co-occurrence matrix (GLCM). Forverification, the measured displacement is checked against the measurement from laser displacementsensors, which shows that the displacement accuracy is 0.05 mm while improving calculation rate by68%. This study also found that the displacement of the bearing system increases with the increase inrotational speed while decreasing with static load
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| 7. |
- Liu, Zhendong, 1983-, et al.
(författare)
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A Numerical Study on Pantograph Raising and Lowering in Multi-Pantograph Operation
- 2017
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Ingår i: The international Journal of railway technology. - : Civil-Comp, Ltd.. - 2049-5358 .- 2053-602X. ; 6:3, s. 51-69
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Tidskriftsartikel (refereegranskat)abstract
- Multi-pantograph operation is a convenient and efficient way to operate railway rolling stock and infrastructure, but the influence between the pantographs makes the system more sensitive and vulnerable than a single-pantograph system. When a train passes through special sections, or falls into an emergency condition, it is necessary to lower one, or all, of the pantographs and then raise them up again. In these circumstances, the motion of the pantographs can introduce a sudden impact to the catenary that may change the configuration of the pantograph combination and its dynamic performance. To address the dynamic performance during pantograph raising and lowering, a numerical study on a multi-pantograph operation is performed with the help of a three-dimensional pantograph-catenary finite element (FE) model and an artificial beam along the catenary is used to guide the motion of the pantograph to describe the pantograph raising-lowering operation. The paper studies the following conditions: the relationship between spacing distance and the span length, various pantograph raising-lowering orders, and different operating positions in a span. The results show that the leading pantograph is little influenced by the raising and lowering movement of any pantograph behind it. However, the trailing pantograph is heavily affected by any operation ahead of it. The dynamic performance of the system depends on the pantograph spacing distance and the operational speed but is little affected by the operating position in a span. To study auxiliary-pantograph operation, where the leading pantograph works as an auxiliary pantograph, this paper shows how an optimal setting of the leading pantograph benefits the trailing pantograph and suggests specifying the speed where the leading pantograph gets into, or out of, service to avoid disruption and to skip unfavourable working conditions.
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| 8. |
- Liu, Zhendong, 1983-, et al.
(författare)
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Application of tuned-mass system on railway catenary to improve dynamic performance
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Finding a simple and practical method to improve the dynamic behaviour of a specific structure is always desirable in civil and mechanical engineering. The railway catenary system is the overhead power line above the track, interacting with the train-based pantograph to transfer electric power. Due to vertical stiffness variation and a propagating wave along the catenary, the fluctuation of the contact force becomes significant with operational speed increasing. Therefore, this has become one of the key factors which limits the operational speed and service life of key components. Wire misalignment, structural errors and uneven mass distribution of the catenary can further deteriorate the contact stability. In order to achieve a higher speed on existing lines, the catenary needs large-scale modification implying long out-off-service time. From the designing aspect, all components directly fixed to the catenary, like clamps, steady arms and other fittings, are made as light and small as possible to minimize disturbances. However, in other engineering applications, some well-designed additional mass systems are adopted aiming to improve their dynamic performance. In order to take advantage of these unavoidable masses on the catenary, an investigation on lumped-mass distribution in single-pantograph and multi-pantograph operations is performed with help of a 3D pantograph-catenary finite element (FE) model. The results show that a rightly-tuned mass, here the implementing location and the elasticity of its connection, can positively change the dynamic performance without implementing large-scale modification to the existing system. Through a brief discussion on the mechanism of this positive effect, this paper proposes that applying some artificial tuned-mass system can be a possible method to overcome unfavourable working conditions or even allow speed increase on existing lines.
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| 9. |
- Liu, Zhendong, 1983-, et al.
(författare)
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Application of tuned-mass system on railway catenary to improve dynamic performance
- 2018
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Ingår i: Engineering structures. - : Elsevier. - 0141-0296 .- 1873-7323. ; 165, s. 349-358
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Tidskriftsartikel (refereegranskat)abstract
- Finding a simple and practical method to improve the dynamic behaviour of a specific structure is always desirable in civil and mechanical engineering. The railway catenary system is the overhead power line above the track, interacting together with the train-based pantograph to transfer electric power. Due to vertical stiffness variation and a propagating wave along the catenary, the fluctuation of the contact force becomes significant with operational speed increasing. Therefore, this has become one of the key factors which limits the operational speed and service life of key components. Wire misalignment, structural errors and uneven mass distribution of the catenary can further deteriorate the contact stability. In order to achieve a higher speed on existing lines, the catenary needs large-scale modification implying long out-off-service time. From the designing aspect, all components directly fixed to the catenary, like clamps, steady arms and other fittings, are made as light and small as possible to minimize disturbances. However, in other engineering applications, some well-designed additional mass systems are adopted aiming to improve their dynamic performance. In order to take advantage of these unavoidable masses on the catenary, an investigation on lumped-mass distribution in single-pantograph and multi-pantograph operations is performed with help of a 3D pantograph-catenary finite element (FE) model. The results show that a rightly-tuned mass, here the implementing location and the elasticity of its connection, can positively change the dynamic performance without implementing large-scale modification to the existing system. Through a brief discussion on the mechanism of this positive effect, this paper proposes that applying some artificial tuned-mass system can be a possible method to overcome unfavourable working conditions or even allow speed increase on existing lines.
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| 10. |
- Liu, Zhendong, 1983-, et al.
(författare)
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Conceptual exploration of power peak shaving by smart train operation in rail freight transport
- 2022
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Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - : Sage Publications. - 0954-4097 .- 2041-3017. ; 236:7, s. 838-849
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Tidskriftsartikel (refereegranskat)abstract
- Powerful electric locomotives with high traction performance are foreseen to be used to boost the overall performanceof freight transport. However, they would exert extra burden on the power supply system, so the power peak demandwould be a bottleneck for future freight transport. To avoid large-scale modifications to the existing systems but ensureoperational reliability, this study investigates the formation of power peaks and explores power peak shaving concepts tolet the existing systems be more reliable and accommodate more freight traffic. Different from many previous studieswhich focus on energy saving, this study aims at lowering the power peak demand by “smart train operation”, i.e.altering the train speed profile without compromising running time. This study is mainly performed by simulation basedon a standardized freight operation with full regenerative braking used. But this study also shows a real case study basedon measurement data of power history from an onboard energy meter. The study shows the formation of power peaksin different conditions and suggests some possible measures to shave the power peak demand. The study also showsthat there is a compromise between power peak shaving and energy saving, to which more attention is needed in futurestudies
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