Vehicle Bogie Research Articles

Operating modal parameter identification of railway vehicle bogie based on k-value optimization variational mode decomposition and second-order blind identification method

Due to the variable operating conditions and strong background noise, the accuracy of modal parameter identification of the railway vehicle bogie is low. This paper proposes a method for identifying operational modal parameters by combining the K-value optimization variational mode decomposition (KVMD) and second-order blind identification (SOBI) method (KVMD–SOBI method). Firstly, the variational mode decomposition (VMD) algorithm is used to adaptively decompose a single-channel vibration signal into intrinsic mode function (IMF) components with different scale characteristics. The feature IMF components are selected through the K-value optimization method based on energy ratio and stability graph. Then, the SOBI algorithm is used to separate the matrix composed of the feature IMF components. And the mode shape and single-mode signal are obtained. Finally, the natural frequency and damping ratio of each order mode are extracted by the single-mode parameter recognition method. Through simulation and experimental verification, it is shown that the proposed method has good noise robustness and can effectively identify the first three modal parameters of railway vehicle bogies in variable-speed operation. At the same time, the feature IMF components extracted by KVMD algorithm eliminate the sensitivity of sensor installation positions and operating conditions to detection results. Therefore, this method is an excellent operational mode identification method based on a single-channel signal with good noise and working condition robustness.

Modal analysis and frequency matching study of subway bogie frame under ambient excitation

A wealth of practical cases indicates that the fatigue failure of subway bogies primarily stems from the modal resonance of the structure. If the modal characteristics of the entire vehicle, including equipment and bogies, are mismatched, rail vehicles may experience abnormal vibrations and noise. Therefore, it is imperative to conduct modal analysis and matching design for subway vehicle bogies to ensure smooth operation, reduce structural vibrations and noise, and enhance vehicle safety and ride comfort. Modal identification methods under the ambient l excitations during vehicle operation were employed to identify the modal parameters of the bogie structure before and after wheel reprofiling and under different load conditions. According to the test results, wheel reprofiling has minimal impact on the modal parameters of the structure, but with an increase in load, the modal frequencies of each order generally increase. This is associated with boundary constraint states, such as the increased stiffness of the bogie air spring with an increase in vehicle load. By comparing the test results with simulation analysis results of the bogie structure under free and constrained states, it is evident that simulating realistic boundary constraint conditions is crucial to ensure the accuracy of the finite element model. Based on frequency isolation criteria and vibration isolation theory, a frequency planning basis for the bogie structure was established. The study found that as the vehicle load increases, changes in the boundary conditions of the bogie affecting the elastic modal frequencies of the structure may have a certain impact on matching design, and may even better comply with the requirements of frequency management equations. This provides a new direction for subsequent scholars researching modal matching design.

Application of the selected multicriterial programming method in the management of rail vehicle bogies in order to extend the servicle life of brake discs

Application of the selected multicriterial programming method in the management of rail vehicle bogies in order to extend the servicle life of brake discs

Experimental and Numerical Investigation of Bogie Hunting Instability for Railway Vehicles Based on Multiple Sensors.

Bogie hunting instability is one of the common faults in railway vehicles. It not only affects ride comfort but also threatens operational safety. Due to the lower operating speed of metro vehicles, their bogie hunting stability is often overlooked. However, as wheel tread wear increases, metro vehicles with high conicity wheel-rail contact can also experience bogie hunting instability. In order to enhance the operational safety of metro vehicles, this paper conducts field tests and simulation calculations to study the bogie hunting instability behavior of metro vehicles and proposes corresponding solutions from the perspective of wheel-rail contact relationships. Acceleration and displacement sensors are installed on metro vehicles to collect data, which are processed in real time in 2 s intervals. The lateral acceleration of the frame is analyzed to determine if bogie hunting instability has occurred. Based on calculated safety indicators, it is determined whether deceleration is necessary to ensure the safety of vehicle operation. For metro vehicles in the later stages of wheel wear (after 300,000 km), the stability of their bogies should be monitored in real time. To improve the stability of metro vehicle bogies while ensuring the longevity of wheelsets, metro vehicle wheel treads should be reprofiled regularly, with a recommended reprofiling interval of 350,000 km.

A Frequency Identification Approach for Damaged Heavy-Haul Railway Bridge with Bogie Accelerations

Bridge structural health monitoring (BSHM) is extensively employed to assess whether bridge damage exceeds maintenance limits and helps maintenance decision-making. Frequency identification is an essential part of BSHM, which utilizes the first-order modal frequency as an evaluation indicator of bridge health status. This paper proposes a method for bridge damage identification based on extracting the first-order modal frequency of the bridge from dynamic responses of vehicle bogies. Firstly, the feasibility of extracting bridge modal frequency from bogie accelerations is theoretically deduced via a vehicle–bridge interaction model. The result indicates that the bogie accelerations encompass three frequency components, namely vehicle driving frequency, vehicle pitching frequency and bridge first-order modal frequency. Then, a multi-domain conjoint analysis method incorporating the time domain, frequency domain and time–frequency domain is proposed to extract the first-order frequency of damaged bridge from bogie accelerations. By defining a damage sensitivity index of the sliding window, the time-domain sensitive boundaries of bogie acceleration to bridge damage are pinpointed. Leveraging prior knowledge of the bridge modal frequency range, the frequency-domain sensitive boundaries bogie acceleration to bridge frequency are determined. On this basis, the sensitive region of bogie acceleration to bridge frequency can be precisely localized in the Hilbert Huang transform spectrum, ultimately identifying bridge frequency through searching local maximum instantaneous energy points within this region. Finally, comprehensive experiments, considering different vehicle speeds and track spectra scenarios, are carried out to investigate the effectiveness and robustness of the proposed method. The results affirm the performance of the method to accurately identify the first-order modal frequency of the damaged bridge, further underscoring the promising prospect of on-board BSHM.

An Alternate Search Method and An Extended Trace Line Method for Wheel‐Rail Contact Patch Centers Detection

AbstractWheel‐rail contact is a link between the vehicle system and the rail system, and the contact processing approach affects accuracy of vehicle dynamic simulation. Contact detection is usually the start of wheel‐rail contact calculation, and detecting precision of contact patch center affect accuracy of contact force calculating results, therefore it is significant to improve detecting precision of contact patch center. An alternate search method (ASM) and an extended trace line method are proposed to improve precision and efficiency of contact patch centers detection. The proposed alternate search method applies Golden Ratio Search Method and variable intervals between grids to detect contact patch centers. To make the detected contact patch centers match rail tangential directions better, an extended trace line method is constructed based on geometrical constraints between contact points and rail tangential directions. Dynamic simulations of a bogie vehicle formed by two wheelsets and a bogie frame negotiating a rail curve are conducted to evaluate effects of the proposed methods. Calculating times of the proposed methods for finishing the simulations are compared to explain computational efficiencies of the different methods. The proposed approaches are real‐time capable and can be used for vehicle dynamics simulations.

Optimization design for the installation position of hold bracket in railway bogie system by uniform design method

ABSTRACT The sensor hold bracket design is an essential element for running safety in the railway vehicle bogie braking system. The installation position of the hold bracket in the bogie system affects the brake sensing performance. This paper aims to determine the optimal installation position of the hold bracket. Three installation angles and one geometry dimension of a holding bracket are selected for the control factors. The uniform design of the experiment method creates a set of experiments. The surrogate models from input and output data are obtained and compared by applying Kriging interpolation and radial basis functions. The final optimal design models of the holding bracket for two surrogate models are determined using the genetic algorithm. The results show that the optimized parameters could substantially improve the installation angle error of the pressure switch from 4° to 0.04°, which aligns with expectations. Finally, to confirm the effect of the control parameters and their reliability and validity, the impact of the pressure switch is expected when the optimal hold bracket model is installed in the railway vehicle bogie system. As a result, the optimal design procedure can improve and reduce the risk of sensor failure during train operation.

Development of laser-arc hybrid welding process of butt joint for bogie pipe crossbeam components

High-speed railway vehicle bogies are the main load-bearing components, which are welded together from steel plates and tubes. Butt joint and T-joint are the main types and the joint thickness is between 8–20mm. The stability of laser-arc hybrid welding (LAHW) process correlated strongly with keyhole behaviour. In this paper, the common quality defects in full penetration root pass by LAHW were analysed. Controlling the root gap is adopted to stabilize the keyhole, to improve the stability of weld quality. A novel type of butt joint with micro structure based on Y-shaped grooves has been designed, to meet both the requirement of controlling root gap and industrial large-scale batch production. Two new structure parameters, 2 mm of the remaining blunt edge thickness and 0.3 mm of the half width of root opening, were proved by the flat plates welding test. Finally, the joint with micro structure and the root pass welding parameters were transferred to the welding process of tube crossbeam components. The LAHW process verification was completed, and the test results showed the process meets the requirements of ISO 15614.

An efficient modelling approach to obtain dynamic properties of equipment coupled to the bogie of vehicle

Modelling the dynamic interaction between equipment and the bogie of a railway vehicle is crucial for the vibration and fatigue analysis of equipment. Current methods such as finite element and rigid-flexible coupling techniques are cumbersome. In this study, an efficient modelling approach is proposed to obtain the dynamic properties of coupled equipment. First, the vehicle and equipment are treated as independent modules, and further coupled using the frequency response function (FRF)-based substructuring method (FBSM). The FBSM is then developed from the finite element method to derive the FRF for the force to stress of equipment. Validation against experimental data and existing methods for a metro vehicle demonstrates the efficacy of our approach. The results indicate that the proposed approach models the vehicle and equipment as independent modules, eliminating the interdependent modeling steps of the previous approach and requiring less computation. The coupled small-mass equipment has a negligible influence on the dynamic properties of the vehicle bogie, but its dynamic properties are sensitive to vehicle and connection stiffness. Moreover, the vibration fatigue of equipment caused by the wheel/rail roughness can also be analyzed with the proposed approach.

A discussion about the limitations of the Eurocode’s high-speed load model for railway bridges

High-speed railway bridges are subjected to normative limitations concerning maximum permissible deck accelerations. For the design of these structures, the European norm EN 1991-2 introduces the high-speed load model (HSLM)—a set of point loads intended to include the effects of existing high-speed trains. Yet, the evolution of current trains and the recent development of new load models motivate a discussion regarding the limits of validity of the HSLM. For this study, a large number of randomly generated load models of articulated, conventional, and regular trains are tested and compared with the envelope of HSLM effects. For each type of train, two sets of 100,000 load models are considered: one abiding by the limits of the EN 1991-2 and another considering wider limits. This comparison is achieved using both a bridge-independent metric (train signatures) and dynamic analyses on a case study bridge (the Canelas bridge of the Portuguese Railway Network). For the latter, a methodology to decrease the computational cost of moving loads analysis is introduced. Results show that some theoretical load models constructed within the stipulated limits of the norm can lead to effects not covered by the HSLM. This is especially noted in conventional trains, where there is a relation with larger distances between centres of adjacent vehicle bogies.

Resolving mode mixing in wheel–rail surface defect detection using EMD based on binary time scale

Due to the mode mixing, empirical mode decomposition (EMD) cannot effectively decompose the vibration signal when the signal is intermittent and pulse interference caused by discontinuous vibration. The methods to solve mode mixing often use noise assistance, such as ensemble EMD (EEMD), complete EEMD (CEEMD), etc. These methods can effectively solve mode mixing, but they also have shortcomings. In EEMD, the added noises not only have residual effects and time-consuming. The drawback of CEEMD is that it is difficult to align during set averaging. In this paper, an improved EMD based on binary time scale (EMD-BTS) is proposed for the fault feature extraction of wheel–rail defect detection. Firstly, the generalized intrinsic mode function (GIMF) is defined based on the time-domain characteristics of non-stationary vibration signals. Then, to tackle the drawbacks of EMD which cannot effectively solve mode mixing caused by signal intermittence and pulse interference, the inherent mode is extracted in the EMD-BTS to decompose the raw signals into GIMFs. Finally, the false components generated by over decomposition are combined based on time-domain cross covariance. A simulation case and a actual case of vehicle bogie are utilized to verify the feasibility of the proposed EMD-BTS. The results indicate that the proposed approach exceeds other typical techniques in extracting intermittent fault features of wheel–rail defect detection.

IMPROVING MANEUVERABILITY OF A WHEELED VEHICLE BY IMPROVING TURN CONTROL METHOD

A large number of scientific works and design developments are devoted to the study and improvement of the properties of maneuverability, which is also a complex (complex) property. At one time, the need to reduce the building volume required the installation of swivel wheels on the front steering axle of the car. However, in this case, additional resistance to the movement of the machine arose, which is due to the discrepancy between the trajectories of the movement of the front outer and inner guide wheels with their trajectories during an ideal turn. The development of the designs of electric vehicles and hybrid vehicles allows for separate control of the front wheels. The analysis of the whole variety of indicators and criteria of maneuverability in general and individual properties was carried out. Unlike other systematization of these indicators and criteria, it is proposed to divide these indicators and criteria into three main groups. All indicators and criteria used to assess the maneuverability of vehicles are also used to assess the maneuverability of wheeled tractors with a center of mass shifted to the rear axle and, therefore, have low controllability. Force and energy criteria can be used in the design of cars and tractors to ensure the ability of the latter to maneuver. In addition, as a result of the study, a combined method for controlling the movement of a two-axle swivel bogie of a wheeled vehicle has been improved due to the fact that its rotation is carried out by two torque control moments. The first of these control torques is generated by the driver through the steering and power cylinder. The second torque control moment is created due to the difference in torques on the wheels of the outer and inner sides of the two-axle swivel bogie. The implementation of these rules for regulating the distribution of traction forces between the sides makes it possible to overcome the resistance to rotation of a two-axle swivel bogie and improve the quality of motion control of the specified bogie and wheeled vehicle. Keywords: maneuverability, separate control, wheeled vehicle, control method, two-axle swivel bogie

Wheel wear reduction of a mechatronic two-axle vehicle controlled with feedforward wheelset steering approaches

The mechatronic vehicle developed within the Shift2Rail projects Run2Rail, Pivot, NEXTGEAR, and Pivot2 is evaluated with respect to wheel wear. The KTH wear model is used to determine the coefficients of Archard’s wear map to reproduce measured worn wheel profiles of the present vehicle running on Metro Madrid line 10. The same wear model is then used to evaluate the performance of the mechatronic vehicle controlled with two variants of a feedforward controller. The first one uses on-board measurements, while the second one is optimised using firefly optimisation algorithms assuming knowledge of the travelled track. The control strategy based on on-board measurements shows improvements above 60% in terms of lost wheel volume due to wear, compared to the standard bogie vehicle. The optimised controller reaches improvements above 70%. Good coherence is found between improvements predicted with the wear number and the ones achieved in terms of lost wheel volume.

Wheel load reconstruction using strain gauge measurements on the bogie frame for strain prediction and fatigue assessment

Knowledge of actual wheel-rail contact forces under a service environment is critical for fatigue damage prediction of rail vehicle bogies. This paper presents a method for reconstructing operational wheel loads based on the strain gauge measurements on the bogie of a tram. The strain gauge placement is solved as an optimisation problem, and the actual load–strain relationship is verified by physical calibrations. A novel calibration arrangement is presented to produce linearly independent load cases for a fully equipped bogie. A good correlation of the reconstructed operational stresses with the measured stresses indicated that the identified loads are valid for fatigue assessment.

Two-axle bogie vibration damping system with additional damping elements

There are no optimal vibration damping designs for safe movement at the present stage of the development of high-speed rail transport. The purpose of improving existing structures is their ability to simultaneously dampen both longitudinal and transverse vibrations. For dynamic research, an analytical method has been developed for calculating the stresses and deformations of the sidewall of the frame of an electric locomotive bogie in motion, taking into account the unevenness of the joints. The result of the work on creating a new design of a two-axle bogie of a railway vehicle, with additional damping elements of the vibration damping system, is the Patent of the Republic of Uzbekistan for the invention No. IAP 06498 [1]. The considered design is universal and suitable for a subway car, motor locomotive, or railcar.

Vertical Nonlinear Damping Experiments and Identification of High Temperature Superconducting Levitation Above Permanent Magnet Track

High temperature superconducting (HTS) magnetic levitation (maglev) train has the potential to become the next generation of high-speed rail transport due to its passive stabilization and virtually no magnetic resistance. From the maglev dynamics views, the damping between the levitated superconductor and the permanent magnet will play an important role to the further vehicle bogie design. The early experiments on HTS maglev damping illustrates that the data was very small in the no-load conditions and lacks the significant exploration of the practical-employed three-seed YBCO bulk as the levitator material. In addition, the empirical expression of the damping coefficient and the working height is still unsolved for applications. Focusing on the vertical damping of the HTS levitator levitated above the practical Halbach magnet track, a vertical vibration damping test bench is designed to conduct experiments in free levitation. Firstly, the effects of three main working factors like load, field cooling height (FCH) and excitation strength, on the vertical damping of the HTS levitation are investigated under different experimental loads. It is interesting to find the HTS levitation shows strong damping behaviors during the practical load operations above the magnet track. Based on the experimental data and theoretical analysis, the vertical damping of the HTS Maglev engineering vehicle is derived as 2×104 Ns/m, which can be close to that of a superconducting electrodynamic levitation vehicle. Secondly, the empirical formula of damping-working height is established by combining the experimental data with the theoretical formula model. It is found that the excitation strength affects the decay of damping but has little effect on the damping magnitude. Furthermore, the phenomenon of keeping constant damping ratio at the same FCH is found even though the other conditions change. This paper show evidences that the HTS maglev system is not a weakly damped system and has a strong nonlinearity in the vertical damping. The proposed empirical formula can provide reference for the bogie design of HTS maglev train.

Intelligent Diagnosis of Bogie Traction Seat Based on PCA-OVO and SVM Optimized by Modified Arithmetic Optimization Algorithm

The bogie traction seat is the main part of urban rail vehicles and its fault status will affect the safe and smooth operation of the vehicles. For the low accuracy of the traditional detection methods, an intelligent fault diagnosis model of the traction seat based on principal component analysis with one versus one (PCA-OVO) and support vector machine (SVM) optimized by modified arithmetic optimization algorithm is proposed. Firstly, for the difficulty of high-frequency data collection under real working conditions, the simulation platform of the bogie of an urban rail vehicle is built, and the vibration signals of the traction seat are collected and processed in different domains, and then the feature extraction and fusion method based on PCA-OVO is used to obtain the sensitive feature set of the traction seat. Finally, the SVM intelligence recognition model is constructed based on the sensitive feature set data, and its parameters are optimally combined and selected by the modified arithmetic optimization algorithm after introducing the cosine factor. The experiments prove the effectiveness of the model. Experimental results show that the model is effective and provides a new model for fault diagnosis of traction seat of urban rail vehicles.

Research on optimization Design of Suspension Parameters of railway vehicle bogies based on surrogate model

Research on optimization Design of Suspension Parameters of railway vehicle bogies based on surrogate model

Sensitivity-based, space rod system multi-objective design of straddle-type monorail vehicle with single-axle bogies

In order to study the influence of the space linkage system on the stability of the straddle-type monorail vehicle with single-axle bogies, the sensitivity analysis of the space linkage system is identified based on the Pearson coefficient method to determine the importance of each component of the single-axle bogies. The dynamics model of straddle-type monorail vehicle with single-axle bogies is established by the multi-rigid body dynamics. The Pearson analysis method is used to identify the key parameters of the space linkage system. Based on that, dynamic response optimization model of space bar system is developed to carry out a multi-objective suspension design optimization process. The results show that the maximum sensitivity parameter for the RMS value of yaw acceleration and pitch angle acceleration is the length of the longitudinal tow bar; there is a correlation of approximately 0.088 between the stiffness K and the damping coefficient C of the hydraulic shock absorber. After optimization the root mean square of lateral acceleration of the optimized single-axle bogie vehicle is reduced by 6.0%.

Experimental characterization of the vibration effects on wheels of a mass rapid transit vehicle

The aim of this paper is to present the results coming from an experimental campaign aimed at the definition of the vibrations acting on a powered and a trailer bogie of a railway vehicle for mass rapid transit during commercial service. The results, coming from multiple sensors placed in specific points of the two wheelsets, can give a significative overview of the dynamic behaviour of the two components, highlighting, when present, notable differences. The available sensors gave the possibility to justify and correlate these differences to specific characteristics of the bogies considered. The study stresses the presence of peculiar cyclic solicitations that the wheels and the wheelset undergo during their service. A deeper investigation of the outcoming signals has been carried out keeping into consideration the frequency content associated to the specific measurement system in use. The results of the experimental campaign highlight that powered wheelsets may experience significant high-frequency vibrations induced by gear pairs. The implications of these findings may represent a significant argumentation in the discussion of the design requirements of wheelsets and wheels.