Dynamic Response Of Vehicle Research Articles

Study on the Vertical Stiffness of Bridge Expansion Joints Based on the Vehicle-Track-Bridge Coupled Model

Bridge expansion joints (BEJs) are equipped at the girder end of long-span railway bridges to ensure the reliable transition of the track. BEJs should have suitable dynamic stiffness to ensure the running safety and stability of the vehicle. To explore the influence of dynamic vertical stiffness of BEJs on the dynamic response of vehicle, track, and bridge, a three-dimensional vehicle-track-bridge coupled model is established, and the influence of sleeper spacing and vehicle speed are taken into consideration. Taking a high-speed railway line in China as a case study, the dynamic response of the whole system is calculated. The results show that (1) the dynamic response of BEJs and the vehicle is affected by the vehicle speed and sleeper spacing. With the increase of vehicle speed and sleeper spacing, the dynamic response of the system increases; (2) the vertical stiffness of BEJs will affect the dynamic response of BEJs and the interaction between the wheel and rail: the vertical dynamic displacement of movable sleeper will exceed the limit if the vertical stiffness of pressure-bearing is insufficient, and the wheel unloading rate may exceed the limit if the vertical stiffness of the cushion plate is insufficient. Based on the results, the larger vertical stiffness of the cushion plate and pressure-bearing is recommended. These results have been applied to the design of BEJs on the studied railway line, which are in good service condition at present.

Dynamic response of railway vehicle with aerodynamic admittance function: An optimized algorithm

Wind effect for railway vehicle was a common problem, and attracted an increasing concentrate, due to the rapidly development of the high-speed railways. In order to evaluate the effect of aerodynamic admittance of a train on the safety, the buffeting force expression (BFE) of vehicle needed to be optimized. In this paper, an advanced approach for the optimization of the BFE of vehicle was proposed. According this methodology, the BFE modified by the aerodynamic admittance function (AAF) took the effect of the vertical fluctuating wind speed into consideration. For the AAFs of railway vehicle obtained by wind tunnel test, a numerical model for the vehicle system, which was fitted based on the expression of frequency responses function of mass-spring-damping system, was presented and verified by the experimental data. The effects of the fitting parameters for the numerical model on the weighting function (WF) and time history of the buffeting force of vehicle were investigated. Then, the WFs of the buffeting force for the vehicle running on the different infrastructure (including flat ground, embankment and bridge) with various wind direction angles, were carried out. Finally, the influences of different flow fields on the dynamic responses of railway vehicle moving on three types of infrastructure were calculated.

Effect of vertical vortex-induced vibration of bridge on railway vehicle’s running performance

The long-span bridge consisting of separated box steel girders is prone to vertical vortex-induced vibration (VIV) within the operating a wind speed range of the train. Based on the wind-train-track-bridge (WTTB) dynamic model, this study presents an analysis method considering VIV effects and investigates the effects of vertical VIVs on the dynamic responses of the train-track-bridge system under crosswinds. It is found that the vertical VIV mainly affects the derailment factor, the offload factor, the vertical car-body acceleration, the vertical car-body Sperling index, and the vertical acceleration of bridge decks, and has less impact on other indexes. The vertical dynamic response of vehicles and bridges increases with the vertical VIV modal order, amplitude and frequency. Furthermore, the impact of the high-order vertical VIV modal is outstandingly more significant than that of the low-order vertical VIV modal.

Analysis of the effects of wind barrier on driving safety and comfort of vehicles on long-span bridges under crosswinds

The installation of wind barriers is generally considered able to improve traffic safety on bridges. Conventionally, the effects of wind barriers are evaluated through the aerodynamic characteristics or dynamic responses of vehicles. In this study, the effects of wind barriers are numerically investigated from the driving safety and comfort perspectives for the first time. The methodology for dynamic analysis of wind–vehicle–bridge (WVB) coupled system is firstly present. Then, the evaluation indexes for driving safety and comfort of vehicles are proposed. A series of wind-tunnel experiments are conducted, and corresponding numerical calculations are performed to discuss the influence of wind barrier parameters i.e., height and opening ratio. Through dynamic responses derived from the calculation results, it is confirmed that: (1) the lateral dynamic responses for both vehicles and bridges considerably increase under winds excitation; (2) the installation of wind barriers can effectively prevent traffic accidents on a bridge, and is thus an effective windproofing measure; (3) however, this method is not beneficial to the bridge structure in terms of stresses and significantly increases the overall vibration value total value (OVTV) of vehicles, which is not conducive to the driving comfort of vehicles on the bridge.

Maglev vehicle-switch girder coupled vibration characteristics analysis based on distributed co-simulation

The violent coupled vibration between the electromagnetically levitated vehicles and the steel switch girder had happened in several engineering practices, especially under the very low speed conditions. In order to simulate accurately the abnormal vibration and explore its underlying causes, this paper develops a distributed co-simulation framework, including maglev vehicle dynamic modelling by SIMPACK software, switch dynamic modelling by ANSYS software and a co-simulation coupler developed by C++ language to implement co-simulation of maglev vehicles and switch girder system. Dynamic response of maglev vehicles and switch girder system under various conditions of running speed and structural damping ratio are simulated and compared to obtain the mechanism and characteristics of coupled vibration. These results agree well with dynamic phenomena happened in the engineering practices. Further analysis shows that the levitation modules are impacted in turn by the vertical misalignments and rotation angles at both ends of switch girder, so that vibration energy of the switch girder cannot be attenuated rapidly by its relatively small damping and dead weight. The severe coupled vibration can be suppressed effectively by adding the tuned mass dampers, but improving constraints of switch girder and optimizing levitation control parameters should be paid more attention in the future.

Research on rail wear of small radius curve in EMU depot

PurposeWith the help of multi-body dynamics software UM, the paper uses Kik–Piotrowski model to simulate wheel-rail contact and Archard wear model for rail wear.Design/methodology/approachThe CRH5 vehicle-track coupling dynamics model is constructed for the wear study of rails of small radius curves, namely 200 and 350 m in Guangzhou East EMU Depot and those 250 and 300 m radius in Taiyuan South EMU Depot.FindingsResults show that the rail wear at the straight-circle point, the curve center point and the circle-straight point follows the order of center point > the circle-straight point > the straight-circle point. The wear on rail of small radius curves intensifies with the rise of running speed, and the wearing trend tends to fasten as the curve radius declines. The maximum rail wear of the inner rail can reach 2.29 mm, while that of the outer rail, 10.11 mm.Originality/valueWith the increase of the train passing number, the wear range tends to expand. The rail wear decreases with the increase of the curve radius. The dynamic response of vehicle increases with the increase of rail wear, among which the derailment coefficient is affected the most. When the number of passing vehicles reaches 1 million, the derailment coefficient exceeds the limit value, which poses a risk of derailment.

A vertical coupling dynamic analysis method and engineering application of vehicle–track–substructure based on forced vibration

PurposeThis study aims to propose a vertical coupling dynamic analysis method of vehicle–track–substructure based on forced vibration and use this method to analyze the influence on the dynamic response of track and vehicle caused by local fastener failure.Design/methodology/approachThe track and substructure are decomposed into the rail subsystem and substructure subsystem, in which the rail subsystem is composed of two layers of nodes corresponding to the upper rail and the lower fastener. The rail is treated as a continuous beam with elastic discrete point supports, and spring-damping elements are used to simulate the constraints between rail and fastener. Forced displacement and forced velocity are used to deal with the effect of the substructure on the rail system, while the external load is used to deal with the reverse effect. The fastener failure is simulated with the methods that cancel the forced vibration transmission, namely take no account of the substructure–rail interaction at that position.FindingsThe dynamic characteristics of the infrastructure with local diseases can be accurately calculated by using the proposed method. Local fastener failure will slightly affect the vibration of substructure and carbody, but it will significantly intensify the vibration response between wheel and rail. The maximum vertical displacement and the maximum vertical vibration acceleration of rail is 2.94 times and 2.97 times the normal value, respectively, under the train speed of 350 km·h−1. At the same time, the maximum wheel–rail force and wheel load reduction rate increase by 22.0 and 50.2%, respectively, from the normal value.Originality/valueThis method can better reveal the local vibration conditions of the rail and easily simulate the influence of various defects on the dynamic response of the coupling system.

Application of C-LSTM Networks to Automatic Labeling of Vehicle Dynamic Response Data for Bridges.

Maintaining bridges that support road infrastructure is critical to the economy and human life. Structural health monitoring of bridges using vibration includes direct monitoring and drive-by monitoring. Drive-by monitoring uses a vehicle equipped with accelerometers to drive over bridges and estimates the bridge’s health from the vehicle vibration obtained. In this study, we attempt to identify the driving segments on bridges in the vehicle vibration data for the practical application of drive-by monitoring. We developed an in-vehicle sensor system that can measure three-dimensional behavior, and we propose a new problem of identifying the driving segment of vehicle vibration on a bridge from data measured in a field experiment. The “on a bridge” label was assigned based on the peaks in the vehicle vibration when running at joints. A supervised binary classification model using C-LSTM (Convolution—Long-Term Short Memory) networks was constructed and applied to data measured, and the model was successfully constructed with high accuracy. The challenge is to build a model that can be applied to bridges where joints do not exist. Therefore, future work is needed to propose a running label on bridges based on bridge vibration and extend the model to a multi-class model.

The Effect of Interface Damage between Slab and Mortar Layer on the Dynamic Performances of Vehicle and Track Systems under the High Frequency Train Loads

To investigate the influences of through-transverse mortar disengagement with different lengths and heights on the dynamic responses of vehicle and track systems under the high frequency train loads, a coupled rigid vehicle–flexible track multi-body dynamics (MBD) model with mortar disengagement was established in SIMPACK platforms with the help of ANSYS software. The results indicate that when the mortar disengagement length is no more than 1 m, the responses of vehicle and track systems are hardly influenced by mortar disengagement with an increase rate of no more than 10% except for the slab displacement. When LMD reaches 1.5 m, the maximum slab displacement exceeds the safety limit of 0.5 mm. The vertical wheel–rail contact force and the rail displacement exceed the safety limit with the mortar disengagement length of 2 m and the mortar disengagement height of 1.5 mm. The most increase rates induced by mortar disengagement are 190% and 272% with regards to the slab displacement and the longitudinal tension stress of slab, respectively, which is significantly detrimental to the service life of slab. The proposed approach has the potential to preliminarily determine the critical mortar disengagement size, which is conductive to relieving the pressure of track maintenance while ensuring the service life of track structures and the operation safety and riding comfort of the vehicle.

Effect of long-wave deviation of stator plane on high-speed maglev train and guideway system

Pre-stressed concrete hybrid guideways are often used in the high-speed maglev transit system. The long-wave deviations of the stator plane based on the initial pre-camber could be possibly caused by temperature and concrete creep. When the high-speed maglev train moves over the guideways system, significant vehicular vibration could be triggered by the long-wave deviations. In the present study, the influence of the long-wave deviations on the dynamic characteristics of high-speed maglev train is investigated. First, the vertical analysis model of the coupled maglev train-guideway system is presented, and the loading model of long wave deviations of the stator plane is determined. Then, the effect of several key parameters, that is, initial pre-camber, the long wave deviations levels, train speeds, and the bridge span, on the dynamic response of maglev train-guideway system is evaluated. The results show that the initial pre-camber will improve the driving safety index and riding comfort level, especially for the middle vehicle of the high-speed maglev train. The results also indicate that the existence of long-wave deviation on the stator plane could deteriorate the driving safety and comfort level of the vehicle. Meanwhile, higher train speed and long-wave deviations levels as well as larger bridge span result in larger vehicle dynamic response.

Investigation of a wheel-rail roller rig for wheel-track defect detection

The wheel-rail defect detection method based on the dynamic response of vehicle and track has attracted much attention, and the rig-based experiment is of great significance to the detection algorithm. Aiming at the common defects of wheel and track, a 1:4 scaled wheel-rail roller rig for wheel-track defect detection with one wheel and one roller is investigated. The wheel has two profiles of the railway vehicle wheel, and the roller also has two profiles of rail. This special profile makes the contact between wheel and roller is more stable in the lateral direction and can simulate the wheel-rail contact. The novel wheel-rail roller rig includes vehicle module, track wheel module, vertical loading device, irregularity input device, corrugation excitation device, stiffness and damping simulation device. Meanwhile, the multifunctional control system and multi-channel vibration acceleration signal data acquisition system are developed. The proposed scaled wheel-rail roller rig has the function of simulating various wheel-rail defects. Finally, the simulation experiment results of track irregularity, wheel flat defects, rail corrugation and structure defects under the rail are analysed. The designed scaled wheel-rail roller rig can simulate various wheel-rail defects well, which is conducive to the research of wheel-rail defect detection algorithm.

The Influence of Track Irregularity in Front of the Turnout on the Dynamic Performance of Vehicles

While the track irregularity in turnout areas has a significant impact on wheel-rail contact, driving safety, and stability, the impact of track irregularity in front of the incoming turnout on vehicles is often overlooked. This paper fills the gaps in the study. As a result, a rigid-flexible coupled dynamic model of the vehicle and turnout is developed. The effect of various irregularities in front of the turnout on the dynamic performance of a vehicle at high speeds has been investigated based on a random sampling method. The results show that different types of track irregularities in front of the turnout have different effects on the dynamic responses of vehicles. The vehicle dynamic performance is most sensitive to short-wavelength (3 m) irregularities in front of the turnout. The alignment irregularity with long-wavelength (40 m) has a significant effect on the wheelset lateral force and lateral acceleration of the vehicle body, caused by two-point contact between the wheel and rail. The frequency range of the effect of the irregularities on the wheel-rail force, safety indicators, and accelerations of the vehicle is mainly below 200 Hz, 50 Hz, and 20 Hz. In this study, a comprehensive assessment of different irregularities is conducted, as well as a quantitative reflection on the effect of the irregularity on the dynamic indicators, providing a reference for maintenance.

Effects of the subgrade differential arch on damage characteristics of CRTS III slab track and vehicle dynamic response

Subgrade differential arch could adversely affect the high-speed railway (HSR) slab track and reduce the quality of train operation. In order to study the effects of the subgrade differential arch on the service condition of the track and operational quality of the vehicle, a novel three-dimensional vehicle-slab track-subgrade coupling dynamics model capable of taking into account the damage of the slab track was established based on the concrete damage plastic (CDP) theory. The model was validated in terms of the analysis of concrete damage behavior and the vehicle dynamics. The results show that under the action of the subgrade differential arch, the base slab of CRTS III slab track damages earlier than the prefabricated slab and has a higher number of macroscopic cracks. The subgrade differential arch could cause interlayer separation between the slab track and subgrade, which will result in the considerable reduction and unevenness of the track stiffness. The increase of the arch amplitude leads to the nonlinear growth of the vehicle dynamics indexes, in which the vertical acceleration of the carbody increases most substantially. The acceleration and Sperling index of the carbody are sensitive to the subgrade arch with the wavelength of 10 m ∼ 20 m. The subgrade arch with the wavelength less than 20 m should be focused on. As the transverse unevenness of the subgrade arch increases, the derailment coefficient, wheel-rail force, and the acceleration of the carbody all increases almost linearly. The vertical Sperling index and the wheel-rail force tend to exceed the limit, which are used as the control indexes to obtain the limit values of the subgrade arch.

A New Moving Kirchhoff–Love Plate Element for Dynamic Analysis of Vehicle–Pavement Interaction

Abstract A new moving Kirchhoff–Love plate element is developed in this work to accurately and efficiently calculate the dynamic response of vehicle–pavement interaction. Since the vehicle can only affect a small region nearby, the wide pavement is reduced to a small reduced plate area around the vehicle. The vehicle loads moving along an arbitrary trajectory is considered, and the arbitrary Lagrangian–Eulerian (ALE) method is used here for coordinate conversion. The reduced plate area is spatially discretized using the current moving plate element (MPE), where its governing equations are derived using Lagrange’s equations. The moving plate element is validated by different plate subjected to moving load cases. Then a vehicle–pavement interaction case with constant and variable speed is analyzed here. The calculation results from the moving plate element are in good agreement with those from the modal superposition method (MSM), and the calculation time with the moving plate element is only one-third of that using the MSM. The moving plate element is accurate and more efficient than the MSM in calculating the dynamic response of the vehicle–pavement interaction.

Bridge Damage and Repair Detection Using an Instrumented Train

The static and dynamic effects of a railway bridge subjected to train loads have been investigated and analyzed to assess its condition. This paper investigates the potential of using repeated dynamic measurements taken on a passing train to determine the condition of a bridge. The results indicated that instrumented trains could be successfully used for ongoing monitoring of condition and, by implication, for identification of the need for repair or rehabilitation. This full-scale approach expands the potential for applications of bridge–vehicle dynamic interaction responses, along with their ability to be demonstrators of successful implementations of decisions on public infrastructure. The work also provided insights into the impact of a stiffer foundation at one pier and greater stiffness in two spans of a viaduct, for which experimental evidence is rarely available. The work also identified some of the challenges of such detection, such as accurate positioning and variability in the speeds of the passing trains.

Transition Permutation Entropy and Transition Dissimilarity Measure: Efficient Tools for Fault Detection of Railway Vehicle Systems

The ordinal pattern is an essential tool to extract the information in time series. However, little attention has been paid to the transition probability matrix of ordinal patterns, which affects the accuracy and comprehensiveness of the extracted information. In this article, we propose a transition permutation entropy (TPE) and a transition dissimilarity measure (TDM) through the transition matrix. The TPE can evaluate the complexity of systems. The TDM measures the dissimilarity between systems through the dynamic transition and the probability distribution of ordinal patterns. The proposed methods are comprehensively evaluated by simulation experiments and vehicle dynamic response data. The results show that both the TPE and the TDM can distinguish complex systems and locate the rail corrugation. The combination of the TDM, multidimensional scaling, and neural networks can be used for fault detection and is better than other distance calculation methods.

Dynamic load testing of a modular truss bridge using military vehicles

Determination of appropriate load factors ensures bridge assessments completed using limit states design are applicable for all potential loading scenarios. Extremely limited research has been completed to determine accurate Dynamic Load Allowance (DLA) values for military vehicle loading of bridges, specifically independent values for tracked and wheeled vehicle types. An experimental testing program was used to assess the dynamic load effects caused by these vehicle categories by subjecting a bridge to loading from multiple different vehicle types at different speeds, while controlling deck surface condition. It was found that tracked vehicles generated approximately half the dynamic bridge response of wheeled vehicles. Using this knowledge, tracked vehicle DLA value recommendations relevant for this bridge are made for use in the North Atlantic Treaty Organization (NATO) Military Load Classification (MLC) system, and in the Canadian Highway Bridge Design Code (CHBDC) and American Association of State Highway and Transportation Officials (AASHTO) bridge code. Further research in this area could lead to strategic increases in tracked vehicle mobility.

Dynamic Characteristics of Metro Vehicle under Thermal Deformation of Long-Span Cable-Stayed Bridge

In order to study the influence of thermal deformation of long-span cable- stayed bridge (LSCSB) on the dynamic characteristics of metro vehicle on the bridge, based on the theory of vehicle-track coupled dynamics, the rigid-flexible coupled dynamic model of metro vehicle-track-LSCSB system is established by using finite element method and multi-rigid-body dynamics. Adopting this model, the deformation of LSCSB subject to temperature is analyzed, then the comprehensive effect of track random irregularity and rail deformation caused by temperature load is considered to study the dynamic characteristics of metro vehicle running through the bridge, and finally the influences of temperature increment and running speed on concerned dynamic indices of vehicle are studied. The results show that the LSCSB deforms obviously subject to temperature load, and the overall performance is that the cooling is arched, and the heating is bent, and the shape variable changes almost linearly with the temperature load. According to the parameters studied in this paper, the rail deformation caused by temperature load increases the wheel-rail vertical force, derailment coefficient and wheel load reduction rate by 1.5%, 3.1% and 5% respectively. The vertical acceleration of the vehicle body decreases by 2.4% under the cooling condition, while increases by 3.7% under the heating condition. The dynamic response of the bridge changes under temperature load. The maximum vertical and horizontal displacement in the middle of the main beam span are 6.24 mm and 2.19 mm respectively, and the maximum vertical and horizontal acceleration are 1.29 cm/s2 and 2.54cm/s2 respectively. The derailment coefficient and vertical acceleration of vehicle body are more affected by temperature load, and the wheel load reduction rate and wheel-rail vertical force are more affected by speed. The conclusion of this paper provides a reference for subsequent scholars to study the influence of thermal deformation on the dynamic response of vehicles on LSCSB.

Theoretical and experimental research on the double lane change maneuver

A virtual double lane change test procedure is proposed based on the NATO AVTP 03-160W requirement. This test procedure simulates an emergency maneuver that determines the vehicle's dynamic stability and decisively influences road safety, being one of the most applied methods of performance evaluation. Using Trucksim modeling and simulation software, the virtual vehicle model and test procedure were established. The experimental data obtained with FED Alpha vehicle helped to validate both models. For this purpose, the vehicle dynamic responses such as steering wheel angle, vehicle lateral acceleration, yaw velocity and roll angle were comparatively analyzed. Important and valid conclusions concerning the optimization of the vehicle’s dynamic behavior were drawn. Ultimately, a methodology to predict the maximum speed to successfully pass double lane change is proposed.

A Novel Derivation of Stationary Vehicle Dynamic Responses and the Use of Stationary Vehicle for Bridge Damage Detection

A Novel Derivation of Stationary Vehicle Dynamic Responses and the Use of Stationary Vehicle for Bridge Damage Detection