Purpose – Rail corrugation is still one of the unsolved challenges in the railway industry, and the abnormal vibration and high-frequency noise caused by it constitute serious adverse effects on the operating environment. How to control corrugation has been an important research theme, and understanding corrugation evolution features is the necessary prerequisite. This study aims to investigate the specific evolution characteristics of corrugation from the contact stick-slip perspective. Design/methodology/approach – The formation and development processes of corrugation are analyzed by using a self-designed scale-down test device. Specifically, the contact stick-slip characteristics under different creepage conditions are analyzed and the formation mechanism of corrugation is summarized. On the basis of corrugation formation, the trend of corrugation development is further emphasized to completely describe the whole process of corrugation evolution. Findings – The results show that, under the determined vertical load condition, the contact interface appears the creep force-creepage negative slope phenomenon in the transverse direction. The cause of short-pitch corrugation on the rail wheel surface under the smaller angles of attack may be related to the inherent vibration frequency of the test device, and the cause of corrugation on the rail wheel surface under the larger angles of attack is mainly related to the stick-slip vibration induced by contact creep saturation. Originality/value – This research explores the evolution characteristics of corrugation by adopting a self-designed scale-down test device, and elucidates the mechanism of corrugation in detail.
Transportation engineering, Railroad engineering and operation
PurposeThis paper conducts a joint analysis of monitoring data in the hidden danger areas of railway subgrade deformation using a data-driven method, thereby realizing the systematic risk identification of regional hidden dangers.Design/methodology/approachThe paper proposes a regional systematic risk identification method based on Bayesian and independent component analysis (ICA) theories. Firstly, the Gray Wolf Optimization (GWO) algorithm is used to partition each group of monitoring data in the hidden danger area, so that the data distribution characteristics within each sub-block are similar. Then, a distributed ICA early warning model is constructed to obtain prior knowledge such as control limits and statistics of the area under normal conditions. For the online evaluation process, the input data is partitioned following the above-mentioned procedure and the ICA statistics of each sub-block are calculated. The Bayesian method is applied to fuse online parameters with offline parameters, yielding statistics under a specific confidence interval. These statistics are then compared with the control limits – specifically, checking whether they exceed the pre-set confidence parameters – thus realizing the systematic risk identification of the hidden danger area.FindingsThrough simulation experiments, the proposed method can integrate prior knowledge such as control limits and statistics to effectively determine the overall stability status of the area, thereby realizing the systematic risk identification of the hidden danger area.Originality/valueThe proposed method leverages Bayesian theory to fuse online process parameters with offline parameters and further compares them with confidence parameters, thereby effectively enhancing the utilization efficiency of monitoring data and the robustness of the analytical model.
Transportation engineering, Railroad engineering and operation
A new type of motor rubber bushing with small radial-to-axial stiffness ratio for high-speed EMUs was designed to meet the installation requirements of motor suspension for a certain high-speed train unit. Through finite element simulation analysis, static stiffness test, fatigue test and running verification, the results show that rubber bushing with this structure can meet the technical requirements, and the pre-compression of rubber is simple and effective, the stiffness range is adjustable, the fatigue performance is good, and it can meet the high temperature tolerance of the motor operating environment.
Purpose – Under the high-speed operating conditions, the effects of wheelset elastic deformation on the wheel rail dynamic forces will become more notable compared to the low-speed condition. In order to meet different analysis requirements and selecting appropriate models to analyzing the wheel rail interaction, it is crucial to understand the influence of wheelset flexibility on the wheel-rail dynamics under different speeds and track excitations condition. Design/methodology/approach – The wheel rail contact points solving method and vehicle dynamics equations considering wheelset flexibility in the trajectory body coordinate system were investigated in this paper. As for the wheel-rail contact forces, which is a particular force element in vehicle multibody system, a method for calculating the Jacobian matrix of the wheel-rail contact force is proposed to better couple the wheel-rail contact force calculation with the vehicle dynamics response calculation. Based on the flexible wheelset modeling approach in this paper, two vehicle dynamic models considering the wheelset as both elastic and rigid bodies are established, two kinds of track excitations, namely normal measured track irregularities and short-wave irregularities are used, wheel-rail geometric contact characteristic and wheel-rail contact forces in both time and frequency domains are compared with the two models in order to study the influence of flexible wheelset rotation effect on wheel rail contact force. Findings – Under normal track irregularity excitations, the amplitudes of vertical, longitudinal and lateral forces computed by the flexible wheelset model are smaller than those of the rigid wheelset model, and the virtual penetration and equivalent contact patch are also slightly smaller. For the flexible wheelset model, the wheel rail longitudinal and lateral creepages will also decrease. The higher the vehicle speed, the larger the differences in wheel-rail forces computed by the flexible and rigid wheelset model. Under track short-wave irregularity excitations, the vertical force amplitude computed by the flexible wheelset is also smaller than that of the rigid wheelset. However, unlike the excitation case of measured track irregularity, under short-wave excitations, for the speed within the range of 200 to 350 km/h, the difference in the amplitude of the vertical force between the flexible and rigid wheelset models gradually decreases as the speed increase. This is partly due to the contribution of wheelset’s elastic vibration under short-wave excitations. For low-frequency wheel-rail force analysis problems at speeds of 350 km/h and above, as well as high-frequency wheel-rail interaction analysis problems under various speed conditions, the flexible wheelset model will give results agrees better with the reality. Originality/value – This study provides reference for the modeling method of the flexible wheelset and the coupling method of wheel-rail contact force to the vehicle multibody dynamics system. Furthermore, by comparative research, the influence of wheelset flexibility and rotation on wheel-rail dynamic behavior are obtained, which is useful to the application scope of rigid and flexible wheelset models.
Transportation engineering, Railroad engineering and operation
Purpose – In view of the difficulty in determining the key parameters d in the Corten-Dolan model, based on the introduction of small loads, damage degrees and stress states to the Corten-Dolan model and the existing improved model, the sequential effects of the adjacent two-stage load were further considered. Design/methodology/approach – Two improved Corten-Dolan models were established on the basis of modifying the parameter d by two different methods, namely, increasing stress ratio coefficient as well as considering the effects of loading sequence and damage degree as independent influencing factors respectively. According to the test data of the welded joints of common materials (standard 45 steel), alloy materials (standard 16Mn steel) and Q235B steel, the validity and feasibility of the above two improved models for fatigue life prediction were verified. Findings – Results show that, compared with the traditional Miner model and the existing Corten-Dolan improved model, the two improved models have higher prediction accuracy in the fatigue life prediction of welding materials whether under two-stage load or multi-stage load. Originality/value – Because the mathematical expressions of the models are relatively simple and need no multi-layer iterative calculation, it is convenient to predict the fatigue life of welded structure in practical engineering.
Transportation engineering, Railroad engineering and operation
Purpose – In order to systematically grasp the changes and matching characteristics of wheel and rail profiles of high speed railway (HSR) in China, 172 rail profile measurement points and 384 wheels of 6 high-speed electric motive unites (EMUs) were selected on 6 typical HSR lines, including Beijing–Shanghai, Wuhan–Guangzhou, Harbin–Dalian, Lanzhou–Xinjiang, Guiyang–Guangzhou and Dandong–Dalian for a two-year field test. Design/methodology/approach – Based on the measured data, the characteristics of rail and wheel wear were analyzed by mathematical statistics method. The equivalent conicity of wheel and rail matching in a wheel reprofiling cycle was analyzed by using the measured rail profile. Findings – Results showed that when the curve radius of HSR was larger than 2,495 m, the wear rate of straight line and curve rail was almost the same. For the line with annual traffic gross weight less than 11 Mt, the vertical wear of rail was less than 0.01 mm. The wear rate of the rail with the curve radius less than 800 m increased obviously. The wheel tread wear of EMUs on Harbin–Dalian line, Lanzhou–Xinjiang line and Dandong–Dalian line was relatively large, and the average wear rate of tread was about 0.05–0.06 mm·(10,000 km)−1, while that of Beijing–Shanghai line, Wuhan–Guangzhou line and Guiyang–Guangzhou line was about 0.03–0.035 mm·(10,000 km)−1. When the wear range was small, the equivalent conicity increased with the increase of wheel tread wear. When the wear range of wheel was wide, the wheel–rail contact points were evenly distributed, and the equivalent conicity did not increase obviously. Originality/value – This research proposes the distribution range of the equivalent conicity in one reprofiling cycle of various EMU trains, which provides guidance for the condition-based wheel reprofiling.
Transportation engineering, Railroad engineering and operation
Reducing the intensity of rail lateral wear remains an important task for industry science. As part of solving this problem, studies are being carried out on the influence of the geometry of the rail track on the wear of rails, the intensity of the force interaction of wheels and rails, the tribological characteristics of the contacting surfaces. The article focuses on the influence on the wear of the geometry of the rail track, namely the rail canting. The definition of the stability of the rail canting has been formulated, which makes it possible to proceed to the assessment of this indicator both in time and in the length of the track section. The assessment of the canting stability over time was carried out on the basis of experimental data obtained in the course of field studies carried out in 2019–2020 on the Moscow Railway. As a result of evaluating these data, the dependence of the change in the average values and the standard deviation of the rail canting in the section on time was built. The average values and standard deviation of the canting in the investigated area are considered in this article as a set of parameters that make it possible to assess the canting stability. In addition to these parameters, it is proposed to evaluate the canting stability along the length of the section based on the canting offset and the standard deviation. The assessment of the stability of the rail canting along the length of the section was carried out using calculations performed in the “Universal Mechanism” software package. As a result of calculations, the values of frame and lateral forces were obtained and an assessment of their maximum and average values at the site was made. This made it possible to answer the question: how does the retraction of the rail canting affect the level of force interaction at the point of contact between the wheels and rails, and, hence, the wear rate?
Abstract. Safe disposal of nuclear waste in deep geological repositories requires secure knowledge transfer or knowledge recovery in time spans of many tens of thousands of years. Never before has any detailed record, knowledge or memory been reliably preserved or recovered over comparable time periods. This challenge has been extensively addressed since the late 1980s, initially during the SANDIA workshops in the USA and more recently in the Nuclear Energy Agency/Organisation for Economic Co-operation and Development (NEA/OECD) project on Preservation of Records, Knowledge and Memory Across Generations (Schröder, 2019). Experts from many disciplines including engineering, the natural sciences, information technology, social studies of science and technology, semiotics, public management, and design as well as artists have contributed to these discussions. Some scholars from the humanities have been involved in working on these issues, especially in recent decades. At the same time, much of the existing work has drawn on assumptions about human history, archaeological monuments and cultural heritage that have been scrutinized and deemed deeply flawed by Joyce (2020). The authors of the present paper are archaeologists and cultural heritage experts. For the past decade, they have been working with the challenge of preserving records, knowledge and memory concerning deep geological disposal sites for nuclear waste (Holtorf and Högberg, 2021). From the perspective of the human sciences, in particular archaeology and heritage studies, the unique task at hand involves not only the previously recognized challenges that require consideration of long-term material durability, linguistic intelligibility, and appropriate sense-making of any communicated information but also two challenges not previously addressed: Human action as informed by cultural and social processes. In designing of various long-term mechanisms, we risk overlooking that what people will do is not going to be governed by mechanics. How human beings learn, reason, value, decide, and act is informed by specific cultural and social processes creating context and meaning. We must avoid ignoring these complexities governing human thinking and agency. This challenge requires more work on understanding how sentient and intelligent beings like humans act in variable contexts across time and space. Our anticipatory assumptions. A proverb states that “nothing ages faster than the future”. In making assumptions about future generations' understandings, meanings, and significances of our nuclear waste we risk “colonizing” the future, fail to embrace variability over time, and miss realizing multiple futures and emerging conditions. We must therefore not foreclose uncertain futures but instead create circumstances favorable for change and transformation of relevant knowledge and memory. This challenge requires more work with processes of translation between generations. The challenges of assessing our anticipatory assumptions and understanding how humans act will also need to be addressed in transmitting records, knowledge and memory for the benefit of future generations.
Mengying HUANG, Jiangping LUO, Wenxing WANG
et al.
There are many types and different shapes of rail defects. Even for the same type of defect, there are differences in the B-Scan images of the ultrasonic rail defect detection software. When the B-Scan image of a certain type of defect changes over a certain range, the detection software cannot identify this type of defect. Therefore, a classification for rail defects based on image processing algorithm was proposed. Firstly, the Tamura texture feature algorithm was combined with the local binary pattern algorithm to extract the feature values of the defect images, and form feature vectors. Secondly, the feature vectors of different kinds of defects were trained by support vector machine, and the optimal classification function was obtained. Finally, the category of untrained defects could be predicted by the optimal classification function. The experimental results showed that the proposed algorithm achieved high accuracy in the classification of rail defect images.
S. V. Vlas'yevskiy, O. A. Malysheva, N. G. Shabalin
et al.
One of the promising ways to increase the capacity of railways is the way to reduce the interval between trains and its packet-mode handling. This method is implemented through the introduction of technology for interval regulation of train traffic. More advanced at present is the technology of interval regulation of train operation according to the "virtual coupling" type, which organizes the operation of trains with a minimum interval between them, which is safe for motion at and between stations. This technology removes the problem of extending the receiving and departure tracks, reduces peak loads on the traction power supply system and the formation time of the virtual coupling structure, and increases the train speed to the yellow traffic signal with safety guaranteed. The technology is implemented due to the presence of an interval control system for train operation, the introduction of on-board automatic locomotive signaling devices ALS-EN and ALS-R, on-board complexes BLOK and KLUB-U (safety devices with satellite navigation and electronic route map), ISAVP-RT-M (auto-driving system for coupled trains) and radio modems for data transmission. The use of these devices in packet mode traffic schedule will reduce the time interval along the sections of the railway and reduce the loss of time when the train runs to the yellow traffic signal. The set of tasks to increase the energy efficiency of applying the technology of interval regulation of train operation according to the "virtual coupling" type should also include the tasks of developing modern rectifier-inverter converters VIP-4000M on AC electric locomotives together with the reactive current block developed in the Railway Implementing Center of the Krasnoyarsk Railway. These developments provide a high power factor of the electric locomotive in the traction and regenerative braking modes (up to 0.96), which will reduce the specific electric energy consumption by electric locomotives for train traction, which will increase the efficiency of the application of the technology of interval regulation of train operation according to the "virtual coupling" type. In July 2019 pilot operational tests of this technology were carried out on the Far Eastern Railway, which showed generally positive results. The paper also presents an analysis of the results on the specific consumption of electric energy for traction and its return to the contact network during regenerative braking by 3ES5K electric locomotives participating in the technology of interval regulation of train operation of the "virtual coupling" type in the sections Khabarovsk-2-Ruzhino and Ruzhino-Khabarovsk-2 of the Far Eastern Railway. These results show an increase in the energy efficiency of electric locomotives using this technology.
The paper describes interaction of high-speed rolling stock and railroad bridge deck and proves the importance of adequate model of wheel (mechanism) and rail (structure) interaction. The model must consist of a rail and slabs of the ballastless deck. The paper characterizes the results of computer simulation of perspective rolling stock passing through high speed railroad bridge, that contains the uniform bridge superstructure for Moscow – Kazan line. The paper shows that in case of resonant bridge superstructure vibration the risk of derailment is high because of the decline of the wheel-rail contact force down to zero, which means wheel uplift. Moreover, the impact of the wheel is the result of uplift and the impact value is similar to the impact from impossible damages of wheels or rail on high speed railroad in consequence of which rail breaking occur. This rail breaking is the most frequent reason of derailment. The impact forces are equivalent to the impact of the fresh flat of the wheel and may be more than 300 kN while static force is equal to 85 kN. The vertical contact force is rising from zero to maximum value for 0.002 to 0.004 s after uplift. The computer simulation results show that it is the bridge superstructure resonance, which leads to impact interaction. The rail fasteners rigidity decline causes vertical interaction force decrease during the impact but the derailment risk still exists during vibration of “bridge – track – train” system.
Nedostatok kvalifikovaných pracovných síl je jednou z najväčších hrozieb pre udržateľnosť a rozvoj vnútrozemskej vodnej dopravy. V dôsledku uvedomenia si dôležitosti situácie vzniká potreba koordinovaného úsilia zo strany všetkých zúčastnených strán tohto priemyselného odvetvia, Európskeho spoločenstva, riečnych komisií, členských štátov i ďalších zodpovedných strán. Zjednodušenie a harmonizovanie legislatívy v oblasti kompetencií, vzdelávania a kvalifikácie, vrátane ich vzájomného uznávania prostredníctvom prijatia Smernice (EÚ) 2017/2397 môže byť ďalším krokom v procese zlepšovania mobility a atraktívnosti vnútrozemskej vodnej dopravy.
Railroad engineering and operation, Industrial engineering. Management engineering
Emergency braking ensures that the EMU stops safely in the shortest distance. This paper presented the triggering condition of emergency braking from the standpoint of fail-safe principle, and introduced the realization method of train security loop. Moreover, the factors of emergency braking implementation need to be considered and the method of emergency barking applied were analyzed, and the diagnostic measures of emergency braking were expounded. The validity and reliability of emergency braking were verified by means of the real tests.
Focusing on the dispersion of the circuit key characteristics, a dispersion analysis method based on the techniques like sensitivity analysis, worst case analysis and yield analysis was proposed. The proposed method was applied on a control circuit. The effectiveness and applicability of proposed method was verified, and it could provide a case study for the following work of the product.