Train Model Research Articles

Effects of crack and structural flexibility on planetary gear system fault feature considering ring gear boundary condition

The crack will inevitably aggravate the transmission system vibration. In addition, the structure of planetary gear train is much more complex, and due to the installation conditions and other factors, the boundary conditions of ring gear are also different (including the pin support constraint and outer rim constraint). In view of the deficiencies of the existing research on the planetary gear train crack morphology, which are mostly based on simple assumptions and lack of experimental verification, the crack growth test is carried out and the theoretical crack morphology is verified. Then, the vibration feature is analyzed based on the obtained crack morphology and the established system-level dynamic model of the planetary gear train (composed of housing, carrier, gear and shaft, etc.). The studies reveal that the fault feature is more obvious when the initial crack location is far away from the tooth root. Under the boundary condition of outer rim constraint, the thinner ring gear can decrease the dynamic response and crack impact, but when restraining the pin support, the observed phenomenon is opposite. After considering the housing flexibility, the vibration is reduced, however, the increasing flexibility weakens the crack fault feature of the planetary gear train.

A novel hierarchical training architecture for Siamese Neural Network based fault diagnosis method under small sample

Although current deep learning-based fault diagnosis methods have made great progress, the accuracy of these models is usually attained based on many balanced training samples, which is quite difficult to meet in real industrial scenarios. In this paper, a Siamese Neural Network (SNN) based fault diagnosis method under small sample conditions is proposed and a novel hierarchical training architecture is designed to train model efficiently. Through pre-training and secondary training of the feature extractor, the SNN training stagnation problem caused by input data is addressed, which fully exploits the deep features of small sample data. Then, a classifier is added to construct the final fault diagnosis network, which improves the diagnosis speed under large test samples, and realizes accurate and efficient fault diagnosis under small sample conditions. Finally, experiments using real rotating machinery datasets show the feasibility and accuracy of the proposed method under small sample.

Modeling and Analysis of TPACK Ability and Training of Primary School Teachers Integrating Information Technology in the Context of Mobile Internet

Modeling and Analysis of TPACK Ability and Training of Primary School Teachers Integrating Information Technology in the Context of Mobile Internet

DEVELOPING STUDENTS’ CRITICAL THINKING WITH THE IMPLEMENTATION OF PROBLEM-BASED LEARNING ACTIVITIES

<em>Activities in the implementation of the problem-based learning model train students in finding information independently related to the problems obtained and train students to be able to solve the problems they face in order to develop students' thinking skills. The purpose of this study is to describe what activities can develop students' critical thinking skills in implementing the PBL model. The method used in this research is a case study in qualitative research by collecting data using self-observation (video recorder). The data collection technique used to obtain the data on the implementation of problem-based learning model in developing students’ critical thinking by doing the activities in learning. The result showed that the activities in problem-based learning model can be implemented in developing students’ critical thinking. This is supported by observational data from self-observation on students’ activities and responses to the implementation of problem-based learning model.</em>

An Overview of the Comprehensive Models for Studying the Electromagnetic Interference of High-Speed Trains

When a high-speed train passes through some sections of the power supply line, its pantograph will inevitably be separated from the power supply line. Although the separation time is extremely short, the pantograph catenary arc (PCA) will be generated during this period. The PCA produces electromagnetic interference (EMI), which cause the potential safety hazard to the operation of high-speed trains. This paper provides an overview of the comprehensive models for high-speed trains. The models can be used to comprehensively research the transient characteristics of the EMI of high-speed trains. It provides a basis for finding the corresponding interference suppression methods, so as to improve the safety of train operation and protect the electromagnetic environment around the train. The proposed model can also be applied to other types of trains by changing some relevant parameters.

Modelling and diagnosis of faults in simple bevel gear train

Gears are a fundamental component of spinning and rotating machinery that transmits power. Different loads and speeds can be applied to gear systems. Faults in gears can lead to breakdown of machines. Therefore, it is essential to keep an eye on the condition of the gears in order to avoid machine failure. Vibration, current and acoustic signature analysis are some of the fundamental methods for monitoring the state of different machineries. Modelling of a system (a virtual prototype) can be used to create enormous amounts of data with different system variables. It can replace the cost and labor involved in experimental analysis. In the present work, two models of a simple bevel gear train are taken into consideration to analyze the response of the system under wear and tear in time as well as frequency domain. The first model is a multi-body dynamics model, developed in CAD based multi-body simulation tool MBS ADAMS and the second model is a six degrees of freedom mathematical model developed in block diagram based Matlab-Simulink environment. In modelling, six different test cases of a simple gear train with healthy pinion, pinion with 20% broken teeth, 40% broken teeth, 60% broken teeth, 80% broken teeth on one tooth and one completely missing tooth are taken for consideration to study the system responses. Analysing the response of the systems, it can be inferred that, the faulty simple gear train (gears with greater amount of wear and tear) is having higher amplitude of vibration compared to that of healthy simple bevel gear train. The amplitude of vibration increases with the wear rate of tooth of the gear. In envelope spectrum, the amplitude of peaks at gear mesh frequencies is more for faulty gear train compared to the healthy bevel gear train which shows the manifestation of faults.

Effect of aerodynamic braking plates installed in Inter-car gap on aerodynamic characteristics of high-speed train

With the continuous increase of train speeds, the aerodynamic drag force provided by aerodynamic braking plates can effectively solve problems of insufficient emergency braking force. The newly proposed aerodynamic braking plates installed in the inter-car gap (ICG) avoid the destruction of the carbody’s strength. In this study, a numerical simulation model of a four-car marshalling train with a speed of 300 km/h is established to study the effect of installation position and opening height of the braking plates mounted in the ICG on the aerodynamic characteristics. The aerodynamic characteristics of the braking plate installed upstream and downstream of the ICG were investigated separately. The downstream plate, which showed better braking performance, was further studied at plate heights of 200 mm, 400 mm, 500 mm, 600 mm, and 800 mm. Results indicate that compared to upstream plates, the aerodynamic drag force coefficient generated by the downstream plates increased by 13.2%. The aerodynamic resistance of the train and the aerodynamic lift of each car increased gradually as the height of the downstream plates increased. Additionally, the braking plate in the ICG had limited anti-crosswind capabilities, with its braking effect significantly weakened in a crosswind of 10 m/s or higher. These results will serve as a guide for the design of aerodynamic braking plates for high-speed trains.

Optimisation of wheel profile of variable gauge high-speed trains

Wheel profile optimisation for variable gauge high-speed trains is required to ensure good vehicle operation performance with two rail gauges, therefore, there is an urgent need to further optimise the wheel profile of variable gauge high-speed trains. This paper proposed the IRSFT-KSM-NSGA-II method to optimise a new wheel profile. Firstly, a new three-parameter improved rotary-scaling fine-tuning (IRSFT) wheel profile generation method was proposed. Then a dynamic model of a variable gauge high-speed train is established, and the clearance between the bushings is considered. The dynamic responses of the vehicle with the generated profiles are calculated and analysed. The wheel profile is optimised using the Kriging surrogate model-Non dominated sorting genetic algorithm-II (KSM-NSGA-II) algorithm. Finally, the dynamic and wear performance of the vehicle before and after the wheel optimisation is verified. The critical speed of the variable gauge high-speed trains is effectively increased, and the ride indexes and safety indexes are improved. When the optimised wheel profile LMB10opt is matched with the rail profile CHN60, the maximum wear depth of the wheel profile is reduced by 11.6%. When the LMB10opt is matched with the P65, the maximum wear depth is reduced by 9.7% and the wear is more uniform.

Analysis of the construction of a port-storm mathematical model of a articulated two-link road train regarding the vertical storage

The article considers possible ways of development and improvement of a flat mathematical model of the movement of an articulated two-link road train considering the track and bringing this model to a spatial model that could consider the change in vertical loads and the subsequent change in the lateral deflection forces, which affect the indicators of turning and controllability of the articulated vehicle. This article proposes constructing a spatial mathematical model of a two-link road train considering the vertical component. The authors consider the problems associated with the movement of a two-track train over uneven terrain and height differences that may occur on the track. They consider the gravitational force's influence on the train's movement and develop a mathematical model that describes this process. The article presents mathematical equations describing the direction of a two-track train in three-dimensional space. They consider the mass of the train, traction forces, air resistance, gravitational force, and reactions from the ground. The authors use numerical methods to solve these equations and conduct computer simulations to study train motion under various conditions. The results of the study demonstrate that the vertical component significantly impacts the movement of a two-track train. It can affect the train's speed, energy efficiency, and stability. The authors conclude with the need to consider the vertical component when building mathematical models of double-track road trains. This paper is essential for researchers and engineers developing and designing road trains. Considering the vertical part will help improve the accuracy of mathematical models and increase the efficiency of two-track road trains in actual operating conditions. The obtained results are essential for developing and improving control systems for two-track road trains, particularly in transport, logistics, and mobile robots. The proposed model can be used to optimize the traffic trajectory and improve the efficiency and safety of the operation of road trains in natural conditions. The proposed model is designed for circular stationary and transient modes of movement of an articulated road train with the possibility of conducting a comparative analysis with a full-scale experiment. Keywords: spatial mathematical model, circular modes, vertical oscillations, articulated train.

The effect of controllable train-tail devices on the longitudinal impulse of the combined trains under initial braking

The 20,000-ton combined train running has greatly promoted China’s heavy-haul railway transportation capability. The application of controllable train-tail devices could improve the braking wave of the train and braking synchronism, and alleviate longitudinal impulse. However, the characteristics of the controllable train-tail device such as exhaust area, exhaust duration and exhaust action time are not uniform in practice, and their effects on the longitudinal impulse of the train are not apparent, which is worth studying. In this work, according to the formation of the Datong–Qinhuangdao Railway, the train air brake and longitudinal dynamics simulation system (TABLDSS) is applied to establish a 20,000-ton combined train model with the controllable train-tail device, and the braking characteristics and the longitudinal impulse of the train are calculated synchronously with changing the air exhaust time, exhaust area, and action lag time under initial braking. The results show that the maximum coupler force of the combined train will decrease with the extension of the continuous exhaust time, while the total exhaust time of the controllable train-tail device remains unchanged; the maximum coupler force of the combined train reduces by 32.5% with the exhaust area increasing from 70% to 140%; when the lag time between the controllable train-tail device and the master locomotive is more than 1.5 s, the maximum coupler force of the train increases along with the time difference enlargement.

Sound-source distribution in the bogie section of a train determined by simultaneous measurement by pressure-sensitive paint and a microphone

Sound-pressure level of acoustic waves from the flow around a 1/8-reduced-scale simplified train model and pressure-fluctuation distribution of the bottom surface of the bogie were measured simultaneously by a microphone and a pressure-sensitive paint (PSP). A high-pressure-fluctuation area was observed on the upstream side on the bogie bottom surface at the peak sound frequency. The phase distribution of the peak frequency of the PSP data was observed to be uniform in the spanwise direction and delayed in the downstream direction. This result indicates that propagation speed of peak surface pressure fluctuation was 66 % of the freestream wind velocity. Thus, the measured peak sound frequency was found to be the same as the theoretical cavity peak frequency given by the Rossiter equation with that propagation speed as a vortex convection velocity. Therefore, the peak sound is concluded to be generated from acoustic feedback in the cavity, which is the gap between the upstream cavity edge and the bogie. Moreover, the difference between the measured and correlated peak sound levels of the bottom surface of the bogie, was no more than 3 dB, where the correlated sound level was calculated by using the Lighthill-Curle equation with coherent output power data.

Modeling of three-link road trains

It is proposed to use graphs for developing the mathematical model of multi-link road trains with coupling devices of different designs. The calculation scheme is formed on the basis of the structure graph of the multi-link road train construction scheme. Next, the structure graph of the mathematical model generalized coordinates levels is written. This allows to develop the mathematical model of appropriate complexity depending on the research objectives. The developed mathematical motion model of a multi-link road train with an elastic-damping joints of their main elements was represented by a system of nonlinear inhomogeneous ordinary differential equations of the second order. The acceleration process for three-link road train with pneumatic coupling devices between train links was modeled.

Optimal intermittent electrification and its effect on battery sizing and energy saving using a high-fidelity train model

The fastest way to decarbonise traction energy of a railway network is full electrification of the network. However, full electrification can be costly and is often delayed due to complicated planning procedures. Often, it is not financially viable to electrify certain sections of the network due to geographical challenges such as hillsides and requirements to raise or lower the tracks. Intermittent electrification can provide a way to reduce emissions on a route without fully electrifying it. This paper presents an optimal intermittent electrification strategy and compares its effects on required battery size to a ‘common-sense’ approach. The “common-sense” approach is a heuristic electrification method where high-power sections of the route are electrified first. Energy savings are demonstrated using a validated high-fidelity bi-mode train model on the Newbury-Plymouth route of Great Western Railway in the UK. Unlike prior research, the optimal electrification strategy considers energy consumptions for both directions of a journey on the route and is therefore optimal regardless of travel direction. The 278-km Newbury-Plymouth route was divided into 50 equal discrete sections for the optimization process, which then identified sections that should be prioritised for electrification as they consume the maximum energy. A high charge/discharge lithium titanite-oxide battery was modelled and installed on the virtual vehicle to determine the required battery sizing for given optimal percentages of intermittent electrification. The battery sizing strategy includes battery wear effects from charge/discharge cycle life and shows the battery life to be 1.42 years if kept at 55°C and 6 years if kept at 25°C. At 36% electrification, using the ‘common-sense’ approach, the battery weighs 10,500 kg and the battery-OLE train reduces the CO2 emissions and energy usage on the route by 83% when compared to the diesel-only train.

Research on a Comfort Evaluation Model for High-Speed Trains Based on Variable Weight Theory

As a result of the continuous improvement in passengers’ requirements for the quality of train operation, the comfort of high-speed train operation has been paid increasing attention. The evaluation of comfort has gradually changed from the narrow sense of a comfort evaluation model containing only vibration to the generalized evaluation of passengers’ overall satisfaction with the ride environment of specific lines. The factors affecting comfort evaluation include physical, physiological, and psychological aspects. To address the problems that the existing comfort evaluation model has a single index and that the weight determination of some indicators is greatly affected by subjectivity, we built a high-speed train comfort evaluation model based on variable weight theory. Combined with the actual working conditions of the Baolan passenger dedicated line, dynamic detection data and noise monitoring data captured by a track inspection car were combined with a passenger ride comfort questionnaire survey. In addition, the initial weight value of each factor was optimized by constructing an equilibrium function to realize the balance between the various factors, so as to realize the comprehensive fuzzy evaluation of high-speed train comfort. The results show that the comprehensive evaluation result of the comfort degree of the high-speed train on the Tongwei to Lanzhou section of the Baolan passenger dedicated line has a grade of II. The fuzzy scores of the evaluations using variable weights and constant weights were analyzed from the perspective of membership degree. The variable weight optimization avoids the one-sidedness and extremeness of the constant weight calculation. The comprehensive evaluation results are closer to the real situation. The research results can provide a reference for the comfort evaluation of high-speed trains with extreme differences in state values and constant weights and help in the acquisition of more realistic evaluation results.

Evaluation of the dynamic behaviors of a train braking system considering disc–block interface characteristics

Disc–block interface properties have prominent influence on the dynamic behaviors of train braking systems. In this study, the tribological characteristics of small-scale train friction blocks with different perforation diameters at the centre of the block surface were investigated using a disc–block test rig. And the Stribeck model parameters of the disc–block friction interface were identified to intuitively characterize the evolution law of stick–slip characteristics with the variation of block perforation diameters. Then, a trailer bogie braking system model of a high-speed train considering the coupling effects between the essential brake unit, wheelset and bogie frame was established. And the identified Stribeck parameters were introduced into the proposed braking system dynamics model to establish a relationship between the friction characteristics of the disc–block interface and the dynamic behaviors of the train braking system. Based on this, the cross-scale analysis was performed to evaluate the dynamic performance of a train braking system affected by the perforated friction block via classical stability theory and numerical simulation. The results show that the friction block with a perforation diameter of 3 mm can effectively suppress the stick–slip vibration of the disc–block friction interface, then reducing the oscillation of system components and enhancing the stability of the entire trailer bogie system.

The effect of the installation angle of a high speed train yaw damper on wheel wear

The yaw damper is of great significance to the dynamic performance of high-speed trains. In this work, the influence of different installation angles of yaw dampers on dynamic responses and wheel wear is investigated. Firstly, the detailed dynamic model of a high-speed train is developed, which includes all kinds of nonlinear factors, such as wheel/rail contact relationship and nonlinear characteristics of various damping, and the influence of the installation angle of the yaw damper on dynamic performances of railway vehicles is investigated. Then the wheel wear prediction procedure is also proposed to obtain the effect of the installation angle of the yaw dampers on wheel wear evolution. The results show that the nonlinear critical speed of railway vehicles gradually increases with the increasing lateral distance of the yaw damper at the frame side. While critical velocity gradually decreases with increasing vertical installation distance of the yaw damper at the car body side. The maximum wheel wear depth will also gradually increase with increasing vertical distance at the car body side and increasing lateral distance of the yaw damper at the frame side when the vehicle runs on the tangent track. Moreover, it is also noticed that the wear depth of the wheel on both sides will gradually increase with the increasing vertical installation distance of the yaw damper at the car body side when the vehicle runs on a curved track. When the lateral installation angle of the yaw damper is less than 0°, the wheel wear rate remains constant and the wear sensitivity of the wheel to lateral installation angle is low, if the lateral installation angle of the yaw damper is greater than 0°, wheel wear rate increases significantly with increasing lateral installation angle of the yaw damper.

Dynamic Characteristics of Urban Rail Train in Multivehicle Marshaling under Traction Conditions

In recent years, urban rail transportation has rapidly developed in China and become one of the most important modes of travel. Most existing studies on the dynamic characteristics of urban rail trains have been based on single-section trains, and there have been fewer studies on marshaling urban rail trains that incorporate traction transmission systems. The dynamic performance of each carriage directly affects the operational reliability and even the running safety of urban rail trains. For this reason, in this paper, a marshaling urban rail train model with a traction transmission system was established and its accuracy was validated by field tests. This dynamics model enables the consideration of the coupling interactions between the gear transmission motion, the vertical, the lateral and the longitudinal motions of the vehicle. First, the model accuracy was validated by field tests. Then, the relationship between the motor torque and the running time of the urban rail train under traction conditions was calculated. Finally, the dynamic performance of each car of the marshaling train was studied. The research results show that there is a clear difference between the dynamics of the motor car and the trailer, and that the motor car is significantly inferior to the trailer. Among the four motor cars, the dynamic performances of the first and last moving cars were worse than those of the other motor cars. Among the two trailers, the trailer at the back was worse than the trailer at the front. The traction transmission system has a greater impact on the vertical and lateral vibration of the train bogie frame and wheelset, but the impact on the vibration of the car body is negligible. This paper provides theoretical support for the research one train dynamic performance optimization and operation safety.

Machine learning driven damper for response control in vehicle–bridge interaction systems

The implementation of machine learning for the real-time prediction of the suitable value of the damping ratio of a semi-active tuned mass damper (SA-TMD) is investigated to ensure enhanced vibration control in vehicle–bridge interaction (VBI) problems. The response assessment of the uncontrolled, tuned mass damper (TMD)-controlled, and SA-TMD-controlled bridge models is performed under the Japanese Shinkansen (SKS) train model. The energy-based predictive (EBP) control algorithm is implemented for the bridge fitted with the SA-TMD. The EBP algorithm-controlled SA-TMD results in more effective suppression of the bridge vibration as compared to the passive TMD. However, the effectiveness of the EBP algorithm reduces for more complex VBI systems because of the increased computational time delay. To circumvent the effect of the delay, a control strategy is proposed based on the weighted random forest (WRF) algorithm. The WRF algorithm is trained based on the data obtained from the EBP algorithm-controlled bridge and implemented to suppress the vehicle-induced vibration of the bridge using SA-TMD. The results demonstrate that the implementation of the newly proposed WRF algorithm-based control strategy nullifies the effects of the computational time delay. Furthermore, it is established that the WRF algorithm suppresses the bridge vibration more effectively than the EBP algorithm.

Efficient Deployment of Dual Locomotives in Regional Freight Rail Transport

The present article focuses on the efficient deployment of dual locomotives in regional rail freight transport considering the quantification of traction energy and energy savings. In the first part of the article, a categorization of dual locomotives, according to their power output in electric and alternative traction (and ratio of both power outputs) is proposed. The potential of deployment of chosen dual locomotives in Central European conditions (a sub-network of Czech railway network around mainlines electrified with AC) is verified by calculation of traction energy consumption of the model train (with two examples of dual locomotives). In addition to non-stop running through the entire line, traction energy consumption of stop (and following acceleration) in each intermediate station is calculated, for a particular direction. Then, appropriate freight train paths for passing passenger trains and saving of traction energy are proposed. The results are supplemented by sensitivity analysis in the form of calculation of traction energy consumption with variable numbers of loaded wagons, with the help of iPLAN/FBS timetabling software. The limitations are the maximum length or gross mass of the train. Finally, the conclusions obtained from the computational examples are evaluated and recommendations for appropriate deployment of dual locomotives and planning of targeted improvements of infrastructure are formulated.

The influence of AAR coupler features on estimation of in-train forces

Inadequate management of large in-train forces transferred through coupler systems of a railway train leads to running and structural failures of vehicles. Understanding these phenomena and their mitigation requires accurate estimation of relative motions and in-train forces between vehicle bodies. Previous numerical studies have ignored inertia of coupling elements and the impacts between couplers. Thus, existing models underestimate the additional dynamic variations in in-train forces. Detailed multi-body dynamic models of two AAR (Association of American Railroads) coupler systems used in passenger and freight trains are developed, incorporating coupler inertia and various slacks. Due to the modeling and simulation complexities involved in a full train model, with such details of coupler system, actual longitudinal train dynamics is not studied. A system comprising only two coupling units, inter-connecting two consecutive vehicles, is modeled. Considered system has been fixed at one end and an excitation force is applied at the other end, to mimic a relative force transmission through combined coupler system. Simulation results obtained from this representative system show that, noticeable influence in in-train forces are expected due to the combined effect of inertia of couplers and intermittent impacts between couplers in the slack regime. Maximum amplitude of longitudinal reaction force, transferred from draft gear housing to vehicle body, is expected to be significantly higher than that predicted using existing models of coupler system. It is also observed that the couplers and knuckles are subjected to significant longitudinal and lateral contact forces, due to the intermittent impacts between couplers. Thus, accurate estimation of draft gear reaction force and impact forces between couplers are essential to design vehicle and coupler components, respectively.