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Proceedings of the Institution of Mechanical Engineers Part F: Journal of Rail and Rapid Transit
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Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0954-4097 - ISSN (Online) 2041-3017
Published by Sage Publications

[852 journals]

Automated status inspection of fastening bolts on freight trains using a
machine vision approach
- Authors: Liu, L; Zhou, F, He, Y.
  Pages: 1629 - 1641
  Abstract: The status inspection and maintenance actions on the mechanical components of freight trains are significant determinants of railway safety. Fastening bolts, as a key component, are widely used to transmit, connect and fasten various parts of freight trains. Their absence can degrade the original structure and lead to accidents. Recently, machine vision approaches have been widely used to inspect the status of mechanical components, thereby reducing costs and avoiding traffic accidents. This paper proposes a visual inspection system that is based on the machine vision approach and can be used to automatically inspect the status of fastening bolts on freight trains. To detect the presence/absence of a fastening bolt in a complex background, a hierarchical detection framework consisting in fault area extraction and fastening bolt detection is proposed. In the first module, a gray projection method is used to divide the fault area that contains the target from the complex background. Subsequently, a fastening bolt detector is designed to verify the candidate image regions. Several gradient-orientation-based features and a classifier can be used to perform the detection task. Experimental results show that the combination of a gradient orientation co-occurrence matrix and a support vector machine has the best classification performance. The proposed inspection system has the advantages of good real-time performance and high inspection accuracy; it achieves an accuracy of 99.96% with a speed of nine frames per second.
  PubDate: 2016-08-08T21:18:46-07:00
  DOI: 10.1177/0954409715619603
  Issue No: Vol. 230, No. 7 (2016)
Flow behaviour and aeroacoustic characteristics of a simplified high-speed
train bogie
- Authors: Zhu, J; Hu, Z, Thompson, D. J.
  Pages: 1642 - 1658
  Abstract: Aerodynamic noise can be a significant problem in the operation of high-speed trains; its prediction is difficult to achieve in an industrial context. The aerodynamic and aeroacoustic behaviour of the flow past a simplified high-speed train bogie at scale 1:10 is studied in this paper; the utilized approach is a two-stage hybrid method that consists in computational fluid dynamics and computational acoustics studies. The near-field unsteady flow was obtained by numerically solving the Navier–Stokes equations with the delayed detached-eddy model and the results were used to predict the far-field noise using the Ffowcs-Williams – Hawkings method. The sound radiated from the same scaled bogie model was measured in an anechoic open-jet wind tunnel. The aeroacoustic characteristics of tandem wheelsets were also investigated for comparison purposes. It was found that the unsteady flow past the bogie is characterized by coherently alternating vortex shedding from the axles and more randomly distributed vortices of various scales and orientations from the wheels and frame. The vortices formed behind the upstream geometries move downstream due to convection and impinge on the downstream bodies, generating a highly turbulent wake behind the bogie. The noise predictions correspond fairly well with the experimental measurements for the dominant frequency of tonal noise and the shape of spectra. Vortex shedding from the axles generates tonal noise, with the dominant peak corresponding to the vortex-shedding frequency. The directivity exhibits a dipole shape for the noise radiated from the bogie. Compared with the wheelsets of the bogie, the noise contribution from the bogie frame is relatively weak.
  PubDate: 2016-08-08T21:18:46-07:00
  DOI: 10.1177/0954409715605129
  Issue No: Vol. 230, No. 7 (2016)
A mixed slab-ballasted track as a means to improve the behaviour of
railway infrastructure
- Authors: Gallego, I; Sanchez-Cambronero, S, Rivas, A, Laguna, E.
  Pages: 1659 - 1672
  Abstract: The existence of zones along a railway line that have abrupt changes in the vertical track stiffness is a well-known phenomenon. It results in the need for constant maintenance activities to keep the quality of the track within an acceptable range; which, in turn, increases the operational and maintenance costs of the line. The causes of these zones are related to features in the superstructure and infrastructure of the line. This longitudinal variation results in the creation of longitudinal heterogeneity in the value of the vertical track stiffness. To deal with this problem, a new design is proposed in this paper that is focused on different infrastructure components. A three-dimensional finite element model of a section of railway track is developed in order to analyse the behaviour of both superstructure and infrastructure in response to the passage of railway loads. The proposed model, and hence the new design, is applied to a real Spanish high-speed rail line that is being constructed between Lemoa and Galdakao in the Basque Country. This line goes through an area with a complex topography and it is projected that about 70% of its length will occur in tunnels or on bridges. This characteristic is used to show the advantages and applicability of the proposed cross-section design to achieve a better homogeneity in the value of the vertical track stiffness and, therefore, to reduce the consequences (from a technical and economic point of view) of this variation on the operation of the line.
  PubDate: 2016-08-08T21:18:46-07:00
  DOI: 10.1177/0954409715605128
  Issue No: Vol. 230, No. 7 (2016)
Evaluating the impact of rail research: Principles to maximise innovation
uptake
- Authors: Palacin, R; Golightly, D, Ramdas, V, Dadashi, N.
  Pages: 1673 - 1686
  Abstract: This paper presents an analysis of railway research carried out in the UK, coupled with interview data from those with active experience of rail research. The aim of this work is to better understand the impact of research in order to identify key factors that influence successful implementation of outcomes, or present barriers to the development and adoption of rail innovation. The paper introduces the innovation context experienced by the rail sector, comparing it with other industries leading to a discussion of research gaps. Data was collected using interviews with industry research experts combined with an analysis of a sample of case studies, dating primarily from 1988 onwards. These data were assessed against three analytical frameworks: barriers and enablers, research process and research impact. Particular emphasis is placed on how research in the rail sector does not always follow the linear process typified by Technology Readiness Levels. The results of this exercise are then discussed leading to the conclusions including the definition of mechanisms that, if followed, could lead to maximising uptake of railway research.
  PubDate: 2016-08-08T21:18:46-07:00
  DOI: 10.1177/0954409715610604
  Issue No: Vol. 230, No. 7 (2016)
Modeling pantograph-catenary arcing
- Authors: Zhu, G.-y; Gao, G.-q, Wu, G.-n, Gu, Z, Wu, J, Hao, J.
  Pages: 1687 - 1697
  Abstract: The performance of the pantograph–catenary system plays a significant role in determining the reliability and safety of a high-speed train. With an increase in train speed, repeated separations between the pantograph and catenary result in an increased number of arcing events, which exacerbate the levels of damage on the pantograph–catenary system, leading to frequent train accidents. The arcing event is a complex phenomenon that is influenced by various factors, and involves interactions between the electromagnetic, thermal and airflow fields. The high temperatures generated by an arc result in ablation of material in the pantograph–catenary system, thus reducing its life expectancy. In order to investigate the mechanism of this damage to the pantograph–catenary system, a model of the arcing phenomenon is established and analyzed. In the proposed model, a set of arc plasma conservation equations are solved to determine the temperature distribution in the arc. The influences of different experimental conditions on the characteristics of the arc and the temperature distributions in the catenary wire and pantograph strip are calculated and discussed. Finally, the results obtained in the simulation studies are compared with realistic arc images recorded using a high-speed camera, and a good agreement is found.
  PubDate: 2016-08-08T21:18:46-07:00
  DOI: 10.1177/0954409715607906
  Issue No: Vol. 230, No. 7 (2016)
Computational fluid dynamics as a means of assessing the influence of
aerodynamic forces on the mean contact force acting on a pantograph
- Authors: Carnevale, M; Facchinetti, A, Maggiori, L, Rocchi, D.
  Pages: 1698 - 1713
  Abstract: This paper discusses the possibility of using computational fluid dynamics (CFD) to assess the influence of aerodynamic forces (aerodynamic uplift) on the mean contact force acting between a pantograph and the contact wire. The analysis consists of experimental tests and CFD simulations, performed in both wind tunnel and on-track scenarios. A method for the computation of the aerodynamic uplift and for the assessment of the contact force imbalance between the leading and trailing collectors is proposed. The method is based on the virtual work principle, and exploits both the numerical forces resulting from CFD analysis, and the Jacobian terms obtained from a kinematic analysis of the pantograph. The proposed model takes into account stationary phenomena, and it is fully validated by means of experimental results.
  PubDate: 2016-08-08T21:18:46-07:00
  DOI: 10.1177/0954409715606748
  Issue No: Vol. 230, No. 7 (2016)
Quantification of the lateral forces in concrete sleeper fastening systems
- Authors: Williams, B. A; Holder, D, Edwards, J. R, Dersch, M. S, Barkan, C. P.
  Pages: 1714 - 1721
  Abstract: Consistent increases in cumulative freight tonnages, combined with the move towards increased higher-speed intercity passenger rail operation, have placed greater demands on North American railroad infrastructure. Concrete sleepers and fastening system components are known to fail at a wide range of life cycle intervals when subjected to demanding loading environments. Such failures can cause track geometry defects, require repetitive maintenance procedures, and present critical engineering challenges. Rail seat deterioration, the degradation of the concrete material beneath the rail, has been identified through a survey of North American Class I railroads to be the most-critical engineering challenge for concrete sleepers. Shoulder/fastener wear or fatigue was identified by the same survey as the second-most-critical engineering challenge related to concrete sleepers. Lateral forces transferred through the fastening system are thought to be a primary cause of degradation of insulators. The objective of this study is to quantify the demands on the insulator through analysis of the transfer of lateral wheel loads into the fastening system by measuring the magnitude of the lateral forces entering the shoulder, a component of the fastening system adjacent to the insulator. The lateral load evaluation device (LLED) was developed at the University of Illinois in Urbana Champaign to quantify these forces. Data captured by the LLED will assist the rail industry in moving towards the mechanistic design of future fastening systems, by quantifying the lateral forces in the fastening system under representative loading conditions. Information gained through this study will also lead to a better understanding of the frictional forces at key interfaces in the fastening system. Preliminary results show that the transfer of lateral wheel loads into the fastening system is highly dependent on the magnitude of the lateral wheel loads and the frictional characteristics of the fastening system.
  PubDate: 2016-08-08T21:18:46-07:00
  DOI: 10.1177/0954409715616997
  Issue No: Vol. 230, No. 7 (2016)
An investigation of railway sleeper sections and under sleeper pads using
a box test apparatus
- Authors: Safari Baghsorkhi, M; Laryea, S, McDowell, G, Thom, N.
  Pages: 1722 - 1734
  Abstract: The railway sleeper, an indispensable component of most railway tracks, is made in diverse materials and geometric forms. Apart from sparse information on their mechanical behaviour, little has been documented about how different sleepers perform as regards track settlement. Box tests have been undertaken to investigate the performance of sections similar in geometry or material composition to some sleeper types used in the railway industry. In tandem, the effects of ‘soft’ and ‘stiff’ under sleeper pads (USPs) were also investigated. Resulting permanent settlements showed that with no USP, the steel section performs better than other sleeper sections. The USPs have, in general, been shown to reduce settlement and more importantly negate the differences between different sleeper sections, suggesting that the sleeper–ballast interface is an important variable for track performance prediction.
  PubDate: 2016-08-08T21:18:46-07:00
  DOI: 10.1177/0954409715613818
  Issue No: Vol. 230, No. 7 (2016)
Grey-system-theory-based model for the prediction of track geometry
quality
- Authors: Xin, T; Famurewa, S. M, Gao, L, Kumar, U, Zhang, Q.
  Pages: 1735 - 1744
  Abstract: The quality of track geometry is an important aspect in railway engineering, as it reflects any deviations and thus the actual condition of a track. Monitoring and prediction of a relevant geometry quality parameter provides an opportunity for effective maintenance, thus creating the advantages of extending the life of the asset, reducing maintenance costs and minimizing possession time requirements. Effective maintenance practice requires a good understanding of the behaviour of track structures over time and also prediction of its condition using only a few inputs. This paper presents a grey-system-theory-based model for predicting track irregularity. Three variants of the grey model are presented and their performances are compared with simple linear and exponential models. Regression models and the grey-system-theory-based models are used to obtain the standard deviation of the longitudinal level from a series of geometry inspection data. The overall performances of the models are evaluated in terms of the regression and prediction accuracies, and it is shown that a Fourier series modification of the grey model has the best performance and the minimum error. The contribution of this paper is the creation of a prediction model for track geometry quality, which is essential for planning and scheduling of preventive geometry maintenance.
  PubDate: 2016-08-08T21:18:46-07:00
  DOI: 10.1177/0954409715610603
  Issue No: Vol. 230, No. 7 (2016)
A nonlinear rubber spring model containing fractional derivatives for use
in railroad vehicle dynamic analysis
- Authors: Shi, H; Wu, P.
  Pages: 1745 - 1759
  Abstract: A nonlinear dynamic model for a rubber spring is created and subsequently used to describe the mechanical behavior of rubber mounts in the suspension system of a railroad vehicle. The characteristics of dynamic stiffness and damping relative to the applied displacement amplitude and frequency are investigated both through simulations and measurements. The model is one dimensional and is based on a superposition of elastic force, frictional force and fractional derivative viscous force. The amplitude dependence is represented by a nonlinear frictional component and a fractional derivative calculus approach is used to account for its frequency dependence. The fractional calculus approach considers previous responses in the current calculation, which results in the memory characteristics of rubber being considered. A linear elastic spring component is still needed to describe its static behavior. The least-squares technique is used to obtain model parameters from measurements, and an overall good agreement between the simulations and measurements is obtained. The model only has five parameters and represents a reasonable compromise between accuracy and computational effort, and thus, it is a suitable tool for railroad vehicle dynamics analysis and simulation.
  PubDate: 2016-08-08T21:18:46-07:00
  DOI: 10.1177/0954409715614871
  Issue No: Vol. 230, No. 7 (2016)
An investigation of subgrade differential settlement on the dynamic
response of the vehicle-track system
- Authors: Zhang, X; Burrow, M, Zhou, S.
  Pages: 1760 - 1773
  Abstract: The construction of non-ballasted slab railway track on existing subgrade soils, or on embankments, is at an early stage of development on Chinese railways. Developing appropriate standards for the allowable amount of subgrade differential settlement that takes into account the dynamic response of the train–track system is one of a number of issues that need to be addressed. To inform the development of such standards, a model based on the theory of vehicle–track coupling dynamics, which considers the weight of the track structure, was created to investigate how differential settlement, in terms of the amplitude, wavelength and position of the settlement along the track, can affect various railway performance-related criteria, including ride quality, stability, vehicle safety and potential damage to the wheel of the train and the rail (i.e. forces at the wheel–rail contact and in the fasteners). The performance of the model was favorably compared with other widely used models described in the literature. The analysis of the study to inform design standards using the developed model demonstrated that the magnitude of the differential settlement influences passenger comfort the most compared with other performance criteria. For the considered CRTS I track, there exists a particular wavelength (8 m for the specific conditions considered) that results in all measures of performance being at their maximum values. Furthermore, the longitudinal position of the settlement waveform in relation to the joints between two concrete slabs, a factor which is not considered in design standards, was shown to influence component deterioration, passenger comfort and safety. The greatest propensity to cause component damage occurs when the beginning or end of the differential settlement waveform corresponds with the inter-slab joint of a concrete base. Accordingly, it is recommended that current design standards should be modified to specify appropriate combinations of amplitude, wavelength and position of the differential settlement to give acceptable measures of performance.
  PubDate: 2016-08-08T21:18:46-07:00
  DOI: 10.1177/0954409715613538
  Issue No: Vol. 230, No. 7 (2016)