Locomotive Vibration Research Articles

Synergistic effects and mechanism of locomotive vibration and chemical dissolution on loess disintegration

Synergistic effects and mechanism of locomotive vibration and chemical dissolution on loess disintegration

Vibration-induced acceleration of infiltration in loess

Coupled effects of railway vibration, rainfall, and drying-wetting cycles contribute to new types of loess disasters such as the collapse and vibration-induced settlement of the railway subgrade, loess mass disintegration, and slope sliding, during the large-scale construction and operation of high-speed or heavy-haul railways in China. This has significant consequences for railways that require millimetre-level deformation control, seriously threatening railway operation and people’s lives. Therefore, for the first time, “five vibration-induced effects” on loess subjected to vibration, water immersion, and dry-wetting cycles are discussed including the vibration-induced acceleration of cracking, infiltration, disintegration, sliding, and subsidence. In this paper, the vibration-induced acceleration of infiltration is discussed mainly. The response of loess to locomotive vibration along railways was determined using field sampling and data processing. The dominant frequency of locomotive vibration are 18−22 Hz and the maximum amplitude is 0.4 mm. Tests regarding the vibration-induced acceleration of the permeability were conducted on intact loess using a newly developed vibration permeability apparatus. The results reveal that the vibration accelerates the water permeability and increases the water saturation of loess. The permeability coefficient of saturated loess under vibration is ~1.5−20 times of that without vibration, reaching a maximum at a vibration frequency of 20 Hz. Vibration-induced infiltration tests were carried out on a loess column and the vibration-induced acceleration of water infiltration, wetting front evolution, and air outflow were analysed. The vibration-induced acceleration of infiltration strongly depends on the dry density, vibration frequency, and vibration amplitude. This pioneering work explores the mechnism of loess disasters triggered by locomotive vibration, rainfall, and drying-wetting cycles.

Experimental investigation of essential feature of polygonal wear of locomotive wheels

Polygonal wear is a common type of wheel surface damage in rail vehicles. Drastic wheel/rail interactions can be induced by wheel polygonization, which directly influences train service performance and maintenance cost, even threatens running safety of rail vehicles. This paper presents an experimental investigation into the fundamental feature of wheel polygonal wear through extensive field measurements. A series of wheel wear measurements and locomotive vibration tests were conducted to reveal the relationship between the wheel polygonization and vibration alarm phenomenon occurred in heavy-haul electric locomotives. A post-processing method to deal with the raw data of wheel polygonization was applied. The characteristics of the wheel polygonization of the locomotives with and without abnormal vibration were compared and analyzed in detail. It is found that the high-order wheel polygonal wear is the root cause of the vibration alarm of locomotive unsprung components. To investigate the elimination effect of locomotive wheel polygonization by different wheel re-profiling methods, tracking measurements of wheel polygonal wear were conducted on three selected locomotives during an interval of the neighboring wheel re-profiling period. The results show that the wheel re-profiling method has a significant effect on the elimination and development of wheel polygonization. The high-order wheel polygonal wear of the re-profiled wheels develops slowly only if it is cleared off.

Vibration Analysis and Control of Locomotive System

Abstract Vibration is an undesirable phenomenon of ground vehicles like locomotives and vibration control of vehicle suspension system is an active subject of research. The main aim of the present work is to modeling and analysis of locomotive system. The simplified equations for dynamical locomotive are firstly established. Then the dynamical nature of the locomotive without control is investigated, and also active control suspension and passive control suspension are compare and discussed. The obtained simulation shows that suspension of the locomotive with feedback control could decrease the locomotive vibration. According to the above control strategy along with angular acceleration it also reduces the possibility of vibration of the locomotive body, to improves the stability of vehicle operation.

Active control of contact force for high-speed railway pantograph-catenary based on multi-body pantograph model

Active control of pantograph is a promising approach in improving the current collection quality of high-speed railway pantograph-catenary system. To address the shortcomings of the lumped-parameter pantograph model used in previous studies, a multi-body model of pantograph is established, and two configurations of installing actuators on a multi-body pantograph are presented. In combination with a nonlinear finite element model of catenary, the control performance is evaluated through several numerical simulations. First of all, the effect of control gains on the control performance is analyzed. Then considering more realistic conditions, the controller time-delay and the limitation of controller sensitivity are included, whose influence on the control performance is investigated. At last, considering realistic external disturbance (strong wind load and locomotive vibration) to pantograph-catenary system the control performance is evaluated in decreasing the fluctuation in contact force as well as eliminating the contact loss. The results indicate that the proposed controller with larger control gains has better performance in decreasing the fluctuation of the contact force between the multi-body pantograph and the nonlinear finite element catenary, but has lower robustness against the controller time-delay. The reduction of controller sensitivity results in a fluctuating degradation of the control performance.

Modelling of track wear damage due to changes in friction conditions: A comparison between AC and DC electric drive locomotives

The locomotive traction motor electric dynamics and its impact on the rail and vehicle have not been investigated deeply in transient wheel–rail contact conditions. Such transient traction behaviour could be more significant to dynamic traction performance and track degradation (i.e. corrugation formation, fatigue, wear, etc.) than steady state behaviour. In order to study this, detailed numerical simulations are performed to investigate the locomotive multi-body dynamic response to a change in contact conditions with an AC and DC electrical traction motor respectively. In particular, creep response, locomotive vibration, and dynamic normal and tractional forces are determined using a developed full scale locomotive dynamics model. The model includes the detailed AC and DC motor dynamics. Further investigation has been undertaken to understand the wear caused during and after the change of friction conditions from dry to wet and wet to dry. The result shows the GT46Ace locomotive AC drive can achieve higher traction efficiency compared to the equivalent DC drive running under notch 8, especially in the wet condition. It is also demonstrated that the AC drive produces slightly lower wear on average than the DC drive after the transient. However, the transient dynamic oscillation of wear caused by the AC drive is significantly higher than the DC drive.

Sensitivity Analysis of the Elastic Properties of Rail Vehicle Suspensions on Vibration Based on the HXN5 Locomotive Model

The dynamic performance of suspensions plays direct role in vibration control of railway vehicles and also has great impact on the ride comfort and operation stability. For assessment of the influence, a method of sensitivity analysis was performed, in which a Multi-Body System (MBS) dynamic model for the HXN5 locomotive counting for significant DOFs and nonlinearities was developed in SIMPACK platform and validated by real tests. More than tens of dynamic simulations were performed by a variety of damping and stiffness coefficients of the primary and secondary suspensions. By simulation, it is found that the vertical stiffness and damping of the primary suspension have the most sensitive influence. The lateral stiffness of the primary suspension, the longitudinal and lateral stiffness as well as the longitudinal and vertical damper of the secondary suspension possess the least effect on the railway locomotive vibration characteristics. It is also shown parameters of the longitudinal stiffness of the primary suspension, the vertical stiffness and lateral damper of secondary suspensions are of intermediate influence.