The dynamic model of the automobile shimmy system considering the sinusoidal road roughness excitation is established, and the response characteristic of the shimmy system is investigated with numerical simulations. Based on the complexification-averaging (CX-A) method, the slow flow equations of the shimmy system are obtained, and the shimmy angle of the front wheel is available on the basis of the

Electrification of road vehicle powertrains involves significant re-design and re-sizing of foundation brakes. Both the usage and the size of hydraulic brake systems can particularly be reduced thanks to the contribution of regenerative braking torque supplied by electric motors, thus reducing cost and weight. In this work, a multi-objective optimal computer-aided engineering (CAE) methodology is proposed

When a four-wheel-drive hybrid electric vehicle (HEV) with dual clutch transmission (DCT) is decelerating while turning, the vehicle often transits from front-wheel hybrid mode to electric mode of the rear hub motors, in order to improve the energy efficiency. However, the mode transition process is accompanied by the driving torque front-to-rear axis conversion and the wheel load transfer. And the

Understanding the relationship between car-body vibration and train aerodynamic forces is very important for developing a reasonable operation plan when the train passes through the complex terrain under strong wind conditions. In this study, car-body vibration under strong wind conditions was initially investigated with a full-scale test. Then the train aerodynamic forces for different rotation configurations

Railway bogies of the Y25 family are the most common type of freight bogies used in Europe. However, this family of bogies presents poor curving performance and a derailment history. Although numerical simulations are a powerful tool to study railway dynamics, derailment scenarios involve complex operational and vehicle conditions that increase the multivariate aspect of the problem. Thus, simulating

Plenty of studies focused on single-direction active suspensions on railway vehicles; at least four actuators per vehicle are needed forconventional active secondary suspensions in both lateral and vertical directions, leading to a sharp increase in costs and reduction inreliability. This paper proposes a novel configuration, lateral-vertical coupled (LVC) active secondary suspension, with only two

The wheel-rail rolling contact finite element model has been generally considered to be a better choice for solving the high-frequency wheel-rail responses and local stress/strain states, compared to the traditional multi-body dynamics model. However, some thorny issues in the wheel-rail finite element analysis need to be solved or avoided, such as difficulties in geometry modelling especially for

A common phenomenon of rail corrugation and its spatial distribution are observed in high-speed rail according to the overall and local field investigations, in which the rail corrugation with a wavelength of 100–300 mm and a depth of 0.01–0.05 mm normally occurs on both the rails in the sharp gradient sections of the high-speed rail. Then, a relevant simulation model of the wheelset–track system supported

In railway heavy haul transportation, the wheel-rail contact interaction has a strong influence on the performance of the entire system. According to the vehicle longitudinal movement conditions - straight/curved tracks and travel speed, contact interaction takes place on different portions along the wheel/rail geometric profiles. Determining wheel/rail contact patches is fundamental both for vehicle

Characteristic values are essential for the design and assessment of driving dynamics during the early stages of the development process of passenger cars. Compared to other aspects of vehicle dynamics however, the relationship between measurable parameters and the subjective perception of vehicle roll dynamics has not been researched extensively. In this paper, a study is presented in which several

Serious wheel polygonal wear usually causes drastic wheel/rail interactions, which threats the running safety of railway vehicles. This paper presents an investigation into the effect of polygonal wear of heavy-haul locomotive wheels on the dynamic performance and wheel/rail interactions through extensive on-site tests and numerical simulations, in which a special attention is paid to locomotive vibrations

Differential steering is an emerging steering concept based on traction force differences between left and right sides of vehicles equipped with independently actuated wheels. Actually, this concept is only used to support classical vehicle designs utilising rack and pinion steering components. However, it may fully substitute such devices to reduce complexity and cut down costs. Since we do not have

To improve the integration of active radial systems of railway vehicles and their adaptability to the vehicle structure, this paper proposes an active radial actuation system based on flexible elastomers. The execution unit of the system has a compact layout and can be embedded in an axle box. The core functional component is a flexible elastic oil-filled rubber bladder, which has active radial actuating

Locomotive-track interaction is a multidimensional task because it goes in many directions depending on the aim of the investigation. One such direction relates to wheel or track damage produced by traction and braking of locomotives under different train operational scenarios. The best option for performing wheel or track damage studies is to use the Exact theory developed by Kalker directly in the

This study aims to provide quantitative insight into the sensitivity of tyre parameters on the performance of the anti-lock braking system (ABS) control algorithms. Unlike conventional sensitivity analysis methods, which depend on a few test cases, in this study, Magic Formula (MF) 6.1 tyre model is used to generate a comprehensive set of thousands of virtual tyres that encompasses all possible combinations

Catenaries are large cable structures which transmit electric current to trains through sliding contact with a pantograph. The finite element method is widely used to model this dynamic interaction problem and obtain the contact force between the pantograph and the catenary. As an alternative, analytical models can also be used to study catenary dynamics, although they require certain simplifications

Tyre, being the most important component of any vehicle, has been studied to quite a lot since its invention. Although, many different tyre models are being used for analysing steady-state tyre forces, there is not enough emphasis on including the transient response in detail. Although, steady state tyre model can be helpful in understanding handling characteristics of the vehicle, it fails when a

Equivalent conicity is an equivalent mean parameter for reflecting the effects of lateral wheel-rail forces on passenger comfort on trains. Based on the asymmetry of the variable cross-section rails in the turnout zone, this paper views the equivalent conicity of a wheelset in the turnout zone as an equivalent conicity of a wheelset in which the wheels match all constant-section asymmetrical rails

To improve the understanding of wheel/rail contact behaviour and damage mechanisms in turnouts, the 3D explicit finite element model of a wheelset rolling over a switch is introduced. This takes into account the arbitrary geometrical profile of the wheel-rail system, the relative motion between switch/stock rail, the nonlinear materials and actual moving postures of the wheelset. Precise frictional

Optimal control is used to study the management of tyre performance for a Formula One car. Tyre friction is compromised by accumulated wear and operation outside the tyre design temperature window – inappropriate thermal operation accelerates tyre wear. In this study tyre wear is modelled as a function of the tyre surface temperature and the power dissipated at the road contact. The tyre's frictional

This paper considers the interaction between a train mounted pantograph and a railway overhead line, presenting results that could be used to reduce the cost of installing overhead electrification, for example, by reducing the need for expensive bridge reconstruction. Ideally, overhead wires would run at a constant height parallel to the track, however, gradients are often unavoidable due to clearance

The longitudinal distance between the centre pivot and the centre of end bogie significantly affects the wheelset lateral force of the outer and inner wheelset. Whether the centre pivot of end bogie of articulated train needs to be offset, and how to set the offset distance, research is still lacking. Taking this as a starting point, this study utilised wheelset lateral force factor to discuss the

Metro trains often encounter the problem of wheel flange wear when they pass through sharp curves, especially for the poor wheel–rail profile matching or lack of lubrication, evidently increasing the maintenance and replacement costs for wheelsets and rails. Based on the field investigation and numerical simulation, the cause of severe flange wear of the original S1002 wheel profile on a Chinese metro

The APM 300 running gear structure follows the structural design of the automobile steering drive axle; therefore, the lateral stiffness of the suspension system is considerable, resulting in poor lateral ride comfort. To improve the lateral ride comfort of the vehicle, this paper proposed a new type of running gear called single air spring running gear (SARG), and according to the original loading

In this study, the aerodynamic forces on a stationary train and moving train as well as the flow fields at the bottom of the trains were compared and analysed. In addition, the numerical algorithm used in the simulation with a stationary train was verified by wind tunnel experimental data. The results show that the distribution law of the drag of the train (without bogie) and bogies is evidently altered

A rigid-flexible coupled train-seat-human model was developed for studying ride comfort of rail vehicles. The weighted acceleration r.m.s. value at the seat pan was used for assessing ride comfort. The contribution of different modes of the carbody to ride comfort was defined from the perspective of power spectral density. The role of first bending mode was more important than other bending modes when

Railway vehicles frequently have derailed during major earthquakes. Although a probabilistic approach based on fragility analysis was established in structural engineering, it has never been applied to railway vehicles. Thus, the aim of this study was to select optimal intensity measures (IMs) and develop fragility curves for the derailment of vehicles. Eight commonly seen IMs were examined to determine

Train derailment can cause not only damage to the train itself but also secondary damage to surrounding structures. For this reason, guard rails are commonly used to prevent secondary damage caused by derailed trains on high-risk lines. In this paper, a 3D vehicle-track dynamics simulation model and a collision contact model were used to investigate the post-derailment dynamic behaviours of the train

Track stiffness irregularity is superficially invisible on rail surface, while causes dynamical impact and track deformation when trains running through. Aiming at this issue, this work presents an investigation on the influence of track stiffness on dynamic behaviours of the high-speed vehicle–track–bridge dynamic system. Primarily, a determination method of track stiffness irregularity is analytically

When designing articulated tractor-trailer systems, engineers should take care to contrast some undesired phenomena associated with the lateral dynamics: the path off-tracking, namely the trajectory deviation of the points of the two units compared to the midpoint of the tractor fore; the rearward amplification of the transverse acceleration. The off-tracking may lead the vehicle tail to invade the

A long-term tracking test was performed on a newly designed high-speed train with the nominal speed of 250 km/h. The wheel roughness and structural vibration were both recorded during two re-profiling cycles. The 3rd order polygonal wear was observed in the early stage. The vibration of the axlebox can be aggravated even at lower speed when the passing frequency of polygonal wear approaches the P2

Although a passive independently-rotating wheel-pair (IRW) is not well suited for curve negotiation due to an inability to provide the necessary steering, an active IRW system offers the potential to realise perfect curving with a satisfactory running stability. Simple control solutions to realise automatic steering and stability of the IRW system are proposed in this paper. In this control approach

The modelling of the wheel–rail contact is fundamental in the railway field since the contact forces directly affect vehicle dynamics, wear, safety and maintenance. In this context, the development of a realistic adhesion model able to describe degraded adhesion conditions is still an open problem because of the complex non-linear behaviour of the adhesion coefficient. To face this problem, in this

In the design of a path-tracking controller for autonomous vehicles, mediating the conflicting objectives among path-tracking, vehicle stabilisation, and low computational cost is a challenging issue. Accordingly, this paper proposes a model predictive control (MPC)-based path-following controller with steering angle envelopes. In contrast to previous MPC-based structure, in which the constraints in

In order to reveal the abnormal vibration of a newly developed 200 km/h medium-speed maglev vehicle with mid-mounted permanent magnet linear synchronous motors at specific speeds, field vibration tests at different running speeds are carried out and analysed in this paper. The accelerations of the linear motor and levitation module were measured during powered running as well as idle running. Data

Hunting stability is a long-standing research topic and has been deeply investigated due to its great influence on railway vehicle dynamic performances. Most of the existing hunting monitoring methods detect only the large amplitude hunting instability (LAHI). However, the small amplitude hunting instability (SAHI) is still hard to be detected accurately and efficiently. To face this challenging problem

Controllable suspension systems have the capability of changing suspension forces. One control approach is to define a cost function with the aim of optimising either ride comfort or handling. Such controllers are usually reactive and not pro-active. Controllers can benefit significantly by having a priori knowledge of the effect that changing the suspension settings will have on the suspension forces

This paper deals with unsteady-state brush tyre models. Starting from tyre-road contact theory, we provide a full analytical solution to the partial differential equations (PDEs) describing the bristle deformation in the adhesion region of the contact patch. We show that the latter can be divided in two different regions, corresponding to two different domains for the solution of the governing PDEs

The vibration environments of railway vehicles can be considered as the source of the vibrations in respective parts of that. With a certain vibration environment above the limit, structural cracks or component drops occur because of the vibration of axle box and bogie frame. Considering the multi-channel and non-normal characteristics of the measured environment of rail vehicles, a statistical induction

The wheel polygonisation is the harmonic wave along the wheel circumference, which has been widely reported in high-speed railway vehicles in China in recent years. The polygonization mechanism has not been fully understood yet, and this work discusses one possible mechanism through several experiments. Firstly, a field test for the CRH3 high-speed train with polygonal wheels is carried out. It is

High-order polygonal wear wheels have been detected on metro express train operating on one metro line in China, which cause fatigue failures of steel coil springs in the primary suspension. A series of tests and theory analysis were conducted to figure out the mechanism of wheel high-order polygonal wear. The wheel out-of-roundness (OOR) measurement results show that the wheels exhibit polygonal wear

In the framework of vehicle-track interaction, this work puts an emphasis on clarifying the influence of sleeper finite element types on system dynamic responses. Three sleeper element types, namely the rigid-body, extensible Euler-Bernoulli beam and solid element are used respectively in the track system modelling with detail mathematical formulations presented. The rails are modelled as Timoshenko

In order to make full use of the direct yaw control (DYC) in electric vehicles with four in-wheel motors (IWMs), this paper presents an adaptive SMC control scheme to improve the handling and stability based on a novel stability index proposed to quantitatively represent stability level. Firstly, a vehicle stability evaluation method is designed based on the front and rear tire slip angles phase plane

This paper presents original data records of linear accelerations and angular velocities of six points of a racing bicycle collected during a ‘genuine’ hands-on shimmy. The records, together with GPS, forward speed data, and action cam videos are thoroughly analysed to understand the actual motion of the bicycle and its parts, at lower (weave) and higher (wobble or shimmy) frequencies. The main goal

Pier settlement is unavoidable in bridge construction and operation processes, thus the influence of pier settlement on the train-track-bridge coupled system becomes a classic and meaningful topic in railway engineering. Aiming at this practical problem, three interesting works are conducted in this paper: (a) a detailed single-pier settlement model (SPSM) is developed with analytic method; (b) a multi-pier

A low-cost experimental-numerical method for the prediction of on-road comfort of city bicycles is presented. Experimental tests are performed by exciting the wheels of the bicycle with impulsive vibrations and measuring the frequency response functions (FRFs) between different sensitive points of the bicycle (i.e. seatpost and steerer tube) and the wheels. Laboratory tests are carried out with the

The wheel-rail contact stress solution is the precondition for many wheel-rail contact problems, such as wheel-rail contact fatigue, plastic deformation and wear, etc. However, vehicle-track interaction generally shows a high degree of randomness due to the uncertainty of excitations, e.g. track irregularities, in the estimation of wheel-rail contact point positions and contact stresses. Moreover,

ABSTRACT In this paper, we analyse the performance of a model predictive controller for coordination of connected, automated vehicles at intersections. The problem has combinatorial complexity, and we propose to solve it approximately by using a two stage procedure where (1) the vehicle crossing order in which the vehicles cross the intersection is found by solving a mixed integer quadratic program

(2020). Theme issue on connected and automated road vehicles. Vehicle System Dynamics: Vol. 58, Connected and Automated Road Vehicles guest edited by: Gabor Orosz and Ilya Kolmanovsky, pp. 669-671.

A cab-based track monitoring system has been developed which makes use of the existing on-board GSM-R cab radio present in the majority of trains operating in the UK. With the addition of a low-cost sensor, type, location and severity of the track defects are reported using the system. The system improves safety and network performance by efficiently directing maintenance crews to the location of defects

The dynamic performance of the vehicle is improved when the bogie of a monorail vehicle passes through the curve in the radial position. This study aimed to derive the analytical relationship between the torque generated by the auxiliary guiding device and the yaw angle between the bogie and the vehicle body based on the geometric relationship between the auxiliary guiding device of the straddle monorail

(2020). Correction. Vehicle System Dynamics: Vol. 58, No. 4, pp. 657-667.

This study presents original new results on measured whole-body vibration (WBV) on passenger’s seat surface and seat base as a function of measured road unevenness in the longitudinal direction. Measurements were provided on nine different cars of six categories operated on about 1860 km of road network. Root mean square (RMS) of the frequency-weighted acceleration was used to quantify the WBV. The

The shift quality of two-speed planetary of electric vehicle is closely related to the characteristics of shift oil pressure. In this paper, the smooth shift control strategy of electric vehicle with two-speed planetary transmission is studied. Firstly, the dynamic models of the two-speed planetary gear train, the shift oil pressure of the hydraulic system and the clutch friction torque are established

Accurately estimating the coefficient of adhesion (CoA) is important to the safety, maintenance, operation and wheel–rail dynamics of railway systems. Studies have reported the influence of various parameters on the CoA and developed subsequent models, but parameter contribution or model estimation accuracy has not been systematically examined. Therefore, this study aims to quantitatively compare the

Monitoring the condition of suspension systems is significant to ensure the safe operation of modern railway vehicles. For this purpose, an online modal identification scheme, denoted as Correlation Subset based Stochastic Subspace Identification (CoS-SSI) is proposed in this paper to monitor the suspension conditions. Because of the widespread of the dynamic contact status between wheel and track

Reducing railway vehicles’ three-dimensional (3D) elastic vibration is needed to improve passenger comfort. This paper presents a 3D analytical model and parameter determination method for the elastic vibration of a carbody. The carbody is modelled as a simple box-type structure consisting of an anisotropic 3D elastic body treated as a continuous system. This model can express complicated 3D elastic

As a significant active safety technology towards fully autonomous driving, driver-automation co-piloting provides a new thinking for enhancing vehicle active safety and relieving driver’s workload. However, the preview pattern divergence between driver and steering assistance system (SAS) may give rise to serious steering conflicts, which reduces driver’s faith in SAS, cause him/her to turn off it

ABSTRACT Most existing models of driver steering control do not consider the driver's sensory dynamics, despite many aspects of human sensory perception having been researched extensively. The authors recently reported the development of a driver model that incorporates sensory transfer functions, noise and delays. The present paper reports the experimental identification and validation of this model

Mode transition plays an important role in the operation of hybrid electric vehicles. The clutch is a key actuator for mode transition, but friction resulting from its use makes it difficult to achieve seamless mode transition. Moreover, as is usual in an electromechanical coupling system, the hybrid powertrain may exhibit complex dynamic behaviours as operating parameters change during mode transition