The rail–wheel interaction in a rail vehicle running at high speed results in large amplitude vibration of carbody that deteriorates the ride comfort of travellers. The role of suspension system is crucial to provide an acceptable level of ride performance. In this context, an existing rail vehicle is modelled in vertical, pitch and roll motions of carbody and bogies. Additionally, nonlinear stiffness and damping parameters of passive suspension system are defined based on experimental data. In the secondary vertical suspension system, a magneto-rheological (MR) damper is included to improve the ride quality and comfort. The parameters of MR damper depend on the current, amplitude and frequency of excitations. At different running speeds, three semi-active suspension strategies with MR damper are analysed for periodic track irregularity and the resulting performance indices are juxtaposed with the nonlinear passive suspension system. The disturbance rejection and force tracking damper controller algorithms are applied to control the desired force of MR damper. This study reveals that the vertical vibrations of a vehicle can be reduced significantly by using the proposed semi-active suspension strategies. Moreover, it naturally results in improved ride quality and passenger's comfort in comparison to the existing passive system.

https://iopscience.iop.org/article/10.1088/1361-665X/aa68f7/pdf

Ride performance of a high speed rail vehicle using controlled semi active suspension system

\n Various bio-inspired vibration isolators have been emerged in recent decades and applied successfully in the protection of sensitive components, improvement of operating comfort, enhancement of control accuracy, etc. They are generally developed by exploiting favorable nonlinearities in biological structures. The main contribution of this work is to provide a comprehensive review of recent studies on the bio-inspired isolators. The methodology of bio-inspired vibration isolation is proposed from the perspective of mechanics based on the elemental theory and design principles. The key isolation mechanisms are classified into three categories according to different dominant forces: stiffness adjustment mechanism, auxiliary mass mechanism, and damping mechanism, respectively. Some representative designs, performance analyses, and practical applications of each type of bio-inspired isolators are also provided. In bio-inspired isolators with variable stiffness, the inherent structural performances can be adjusted to deal with variation in external load. The auxiliary mass mechanism utilizes nonlinear inertial effects to achieve ultralow frequency vibration isolation. Unique damping mechanism of bio-inspired structures is often studied to protect devices and equipment from impact loads. Bio-inspired vibration methods can also be applied in active/semi-active control systems with advantages of low energy consumption and high robustness. Finally, the review ends with conclusions, which highlight resolved and unresolved issues and provide a brief outlook on future perspectives. This review aims to give a comprehensive understanding of bio-inspired isolation mechanism. It also provides guidance on designing new bio-inspired isolators for improving their vibration isolation performance.

Bio-Inspired Vibration Isolation: Methodology and Design

A nonlinear vibration isolator supported on a flexible plate: analysis and experiment

A 2.5D finite element and boundary element model for the ground vibration from trains in tunnels and validation using measurement data

This study aims to effectively and robustly suppress the low-frequency vibrations of floating slab tracks (FSTs) using dynamic vibration absorbers (DVAs). First, the optimal locations where the DVAs are attached are determined by modal analysis with a finite element model of the FST. Further, by identifying the equivalent mass of the concerned modes, the optimal stiffness and damping coefficient of each DVA are obtained to minimise the resonant vibration amplitudes based on fixed-point theory. Finally, a three-dimensional coupled dynamic model of a metro vehicle and the FST with the DVAs is developed based on the nonlinear Hertzian contact theory and the modified Kalker linear creep theory. The track irregularities are included and generated by means of a time–frequency transformation technique. The effect of the DVAs on the vibration absorption of the FST subjected to the vehicle dynamic loads is evaluated with the help of the insertion loss in one-third octave frequency bands. The sensitivities of the m...

Low-frequency vibration control of floating slab tracks using dynamic vibration absorbers

The geometric filtering phenomenon is first analyzed with a simplified vertical vehicle model. Analytical solutions obtained with this model show that geometric filtering phenomenon consists of ‘wh...

On the resonant vibration of a flexible railway car body and its suppression with a dynamic vibration absorber

A vertical vehicle–track coupled dynamic model, consisting of a high-speed train on a continuously supported rail, is established in the frequency-domain The solution is obtained efficiently by use of the Green's function method, which can determine the vibration response over a wide range of frequency without any limitations due to modal truncation Moreover, real track irregularity spectra can be used conveniently as input The effect of the flexibility of both track and car body on the entire vehicle–track coupled dynamic response is investigated A multi-body model of a vehicle with either rigid or flexible car body is defined running on three kinds of track: a rigid rail, a track stiffness model and a Timoshenko beam model The results show that neglecting the track flexibility leads to an overestimation of both the contact force and the whole vehicle vibration response The car body flexibility affects the ride quality of the vehicle and the coupling through the track and can be significant in certain frequency ranges Finally, the effect of railpad and ballast stiffness on the vehicle–track coupled vibration is analysed, indicating that the stiffness of the railpad has an influence on the system in a higher frequency range than the ballast

Vertical random vibration analysis of vehicle–track coupled system using Green's function method

High structural modal frequencies of car body are beneficial as they ensure better vibration control and enhance ride quality of railway vehicles. Modal sensitivity optimization and elastic suspens...

https://journals.sagepub.com/doi/pdf/10.1177/1687814016643640

Analysis of modal frequency optimization of railway vehicle car body

Method of multi-mode vibration control for the carbody of high-speed electric multiple unit trains

To suppress vertical flexural vibration of a railway vehicle car body, a new passive control method by mounting dampers on the longitudinal beams of the car body underframe is proposed. The method is firstly studied by an Euler-Bernoulli beam model using Green’s functions, then it is further verified by a nonlinear dynamic model of the vehicle. Results show that the car body flexural vibration can be noticeably reduced by this method. It is better to mount the damper near the car body centre. The higher damping coefficient of the damper, the more effective in decreasing the car body first vertical bending vibration. The higher the rigidity of the damper bracket and rubber bush, the better performance of the damper. It is found that when mounting six dampers at proper positions, the damping coefficient of each damper is 1.33×107 N·s/m, even if the first vertical bending frequency of the studied car body is only 7.2 Hz, a very good ride quality will be achieved when the vehicle runs at 250 km/h.

Dao Gong

Papers

On the resonant vibration of a flexible railway car body and its suppression with a dynamic vibration absorber

Vertical random vibration analysis of vehicle–track coupled system using Green's function method

Analysis of modal frequency optimization of railway vehicle car body

Method of multi-mode vibration control for the carbody of high-speed electric multiple unit trains

Passive control of railway vehicle car body flexural vibration by means of underframe dampers