A theoretical vibration‐reduction effect analysis of the floating slab track supported by nonlinear variable stiffness isolators and semi‐active magneto‐rheological dampers

2021 ◽  
Vol 28 (11) ◽  
Author(s):  
Zeming Zhao ◽  
Kai Wei ◽  
Fang Cheng ◽  
Huailong Li ◽  
Ping Wang
Keyword(s):  
Vibration Reduction ◽  
Variable Stiffness ◽  
Effect Analysis ◽  
Slab Track ◽  
Reduction Effect ◽  
Magneto Rheological

scholarly journals Evaluation Method of the Vibration Reduction Effect Considering the Real Load- and Frequency-Dependent Stiffness of Slab-Track Mats

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 452
Author(s):  
Zeming Zhao ◽  
Kai Wei ◽  
Wenhao Ding ◽  
Fang Cheng ◽  
Ping Wang
Keyword(s):  
Frequency Dependence ◽  
Insertion Loss ◽  
Vibration Isolation ◽  
Evaluation Method ◽  
Vibration Reduction ◽  
Frequency Dependent ◽  
Tangent Stiffness ◽  
Slab Track ◽  
Secant Stiffness ◽  
Reduction Effect

The purpose of this research was to investigate and improve the accuracy of the existing slab-track mat (STM) specifications in the evaluation of the vibration reduction effect. The static nonlinearity and dynamic mechanical characteristics of three types of STMs were tested, and then a modified fractional derivative Poynting–Thomson (FDPT) model was used to characterize the preload and frequency dependence. A modified vehicle–floating slab track (FST) coupled dynamic model was established to analyze the actual insertion loss. The insertion loss error evaluated by the frequency-dependent tangent stiffness increased with the increase in STM nonlinearity, and the error obtained by the third preload tangent stiffness was usually greater than that of the second preload. Compared with the secant stiffness, the second preload frequency-dependent tangent stiffness was more suitable for evaluating STMs with high-static–low-dynamics (HSLD) stiffness. In order to reflect the frequency dependence effect and facilitate engineering applications, it is recommended that second preload tangent stiffness corresponding to the natural frequency of the FST be used for evaluation. Furthermore, the insertion loss of the STMs with monotonically increased stiffness decreased as the axle load increased, and the opposite was true for the STMs with monotonically decreased stiffness. The vibration isolation efficiency of the STMs with HSLD stiffness was both stable and better than that of the STMs with monotonic stiffness.

Influence of static preload on vibration reduction effect of floating slab tracks

2018 ◽  
Vol 25 (6) ◽  
pp. 1148-1163 ◽  
Author(s):  
Minghang Li ◽  
Meng Ma ◽  
Weining Liu ◽  
Bolong Jiang
Keyword(s):  
Vibration Reduction ◽  
Coupled Model ◽  
Mitigation Measures ◽  
Vehicle Body ◽  
Reference Case ◽  
Slab Track ◽  
Vibration Responses ◽  
Reduction Effect ◽  
Impact Vibration

To effectively reduce the railway vibration and its environmental impact, vibration mitigation measures are increasingly used. The vibration reduction effect of railway tracks is described quantitatively by insertion loss (IL). ILs obtained from in situ measurements under moving train loads and laboratory tests under artificial excitation differ significantly due to the different track loading state between these two methods. The differences of track loading state are induced by the moving effect of train passages and the preloads effect of vehicle masses, the latter of which is a significant factor to discuss in this paper. In order to study the static preload by vehicle masses influence on the vibration reduction effect in isolated tracks, the steel spring floating slab track and regular slab track, as a reference case, were compared. First, a theoretical simplified model was constructed, following which a finite–infinite element coupled model was built, which was calibrated by experimental test results. Impact loads were applied to both tracks with preloads using unsprung wheelsets or sprung vehicle-body masses, with the total mass varying from 0 t to 30 t. The results demonstrate that the increase in preload of unsprung mass makes the natural frequencies further reduced, and the peak IL value increased from 39 dB to 48 dB. The increase in preload has a significant effect on vibration responses below 5 Hz, and the application of the preload has different effects on the reduction effect in different frequency ranges.

A Variable Stiffness Vibration Isolation System Based on Magneto-Rheological Elastomer

2012 ◽  
Vol 452-453 ◽  
pp. 659-662
Author(s):  
Wei Wang ◽  
Yi Min Deng
Keyword(s):  
Shear Modulus ◽  
Vibration Isolation ◽  
Variable Stiffness ◽  
Control Area ◽  
Frequency Range ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Vibration Isolators ◽  
Magneto Rheological ◽  
Conventional Type

Vibration isolation is a most widely used vibration protection method.The stiffness of vibration isolators in existing conventional type of vibration isolation system is usually of fixed value. This limits the system in exhibiting its vibration isolation effect in that, it has poor results for lower frequency vibration, especially for resonance frequency. Magneto-rheological elastomer is a new branch of Magneto-rheological materials. It’s an intelligent materials in that it’s shear modulus can be controlled by a magnetic field. It has wide application prospects in the vibration control area. This paper proposes using adjustable stiffness of magneto-rheological elastomer vibration isolation in vibration isolation system. By changing the current of vibration isolators coil to control the shear modulus of magneto-rheological elastomer, it can adjust the stiffness of the isolation system, making the system obtain wider vibration isolation frequency range. By exploying SimuLink software to analyze the vibration isolation system, it is found that such a design is effective and applicable.

Vibration-reduction optimization of the point-supporting floating-slab track based on local resonance mechanism

2021 ◽  
pp. 107754632110598
Author(s):  
Hao Jin ◽  
Hongying Wang ◽  
Zheng Li ◽  
Xin Zhou
Keyword(s):  
Band Gap ◽  
Vibration Reduction ◽  
Dynamic Test ◽  
Vertical Vibration ◽  
Resonance Theory ◽  
Support Structure ◽  
Continuous Increase ◽  
Local Resonance ◽  
Slab Track ◽  
Point Support

With the continuous increase of subway operating mileage, the problem of subway vibration has become more and more significant. Nowadays, the point-supported floating-slab track is recognized as the best method to control track vibration, which is mainly designed based on the mass-spring-damping theory. How to further improve the vibration control ability of the point-supported floating-slab track? In this paper, a new type of rubber point-supported floating slab track is designed based on the local resonance theory. Through calculation and dynamic test, it is obtained as follows: (1) The band gap of the point support structure by local resonance type depends on the two vertical vibration modes. (2) As the elastic modulus of the cladding layer increases, the bandwidth of the band gap of the corresponding structure increases significantly. (3) The increase of the vibrator density can increase the bandwidth, while reducing the start and stop frequencies, which is beneficial to attenuate the resonance of the floating-slab track. (4) The cushion material parameters of point support structure by local resonance type 2 will not affect the band gap. The increase in sleeve density will reduce the band gap, which is not conducive to vibration reduction. Local resonance type floating-slab track will be the development direction of track vibration-reduction measures in the future.

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