scholarly journals A magnetorheological elastomer rail damper for wideband attenuation of rail noise and vibration

2019 ◽  
Vol 31 (2) ◽  
pp. 220-228 ◽  
Author(s):  
Shuaishuai Sun ◽  
Jian Yang ◽  
Tanju Yildirim ◽  
Donghong Ning ◽  
Xiaojing Zhu ◽  
...  
Keyword(s):  
Decay Rate ◽  
Variable Stiffness ◽  
Magnetorheological Elastomer ◽  
Dynamic Vibration Absorber ◽  
Noise And Vibration ◽  
Practical Applications ◽  
Theoretical Predictions ◽  
Damper Design ◽  
Conventional Rail ◽  
Rail Damper

The noise and vibration effects of rails can have a significant impact on the environment surrounding the railways. Rail dampers are elements that are attached to the sides of the rail and can improve the track decay rate of rail and then enhance the rails’ ability to attenuate noises and vibrations. However, in practical applications, the most efficient rail damper design still cannot adjust its own parameters to adapt to different requirements because their stiffness and damping are fixed after designed. In this work, a tunable magnetorheological elastomer rail damper that works on the principle of a dynamic vibration absorber has been designed, analysed, characterised, and experimentally tested for the suppression of railway noise and vibration. The new rail damper incorporates variable stiffness magnetorheological elastomer layers, whose stiffness can be controlled by an externally applied magnetic field, to realise adaptive characteristics. Experimental characterisations of the magnetorheological elastomer rail damper were performed with an electromagnetic shaker. Subsequently, theoretical predictions of the track decay rate of a UIC-60 rail with different rail dampers and without rail damper were conducted; simulation results verified that magnetorheological elastomer rail dampers can improve the track decay rate of rail over a wider frequency range compared to conventional rail dampers and thus the performance of the magnetorheological elastomer rail damper outperforms other conventional rail dampers on rail noise reduction.

scholarly journals Design of a Real-Time Adaptively Tuned Dynamic Vibration Absorber with a Variable Stiffness Property Using Magnetorheological Elastomer

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Toshihiko Komatsuzaki ◽  
Yoshio Iwata
Keyword(s):  
Variable Stiffness ◽  
Vibration Absorber ◽  
Property Value ◽  
Magnetorheological Elastomer ◽  
Dynamic Vibration Absorber ◽  
Dynamic Vibration ◽  
Dependent Property ◽  
Dynamic Absorber ◽  
Frequency Tunable ◽  
Tunable Frequency

An elastomer composite with controllable stiffness, known as a magnetorheological elastomer (MRE), is used in a dynamic vibration absorber whose natural frequency is tuned adaptively to the disturbance frequency through the application of an external magnetic field. The field-dependent property test of the fabricated MRE sample shows that the stiffness changes by more than six times compared to the baseline property value at a 40% iron powder volume concentration. The MRE is then used to fabricate a frequency-tunable dynamic absorber for mitigating transient vibrations of a one-degree-of-freedom system. Investigations show that the proposed absorber outperforms a conventional passive-type absorber throughout the tunable frequency range.

Adaptive Tuned Dynamic Vibration Absorber With Variable Stiffness Property Using Magneto-Rheological Elastomers

2013 ◽  
Author(s):  
Toshihiko Komatsuzaki ◽  
Yoshio Iwata ◽  
Hirofumi Ringe ◽  
Keiji Kawagoshi
Keyword(s):  
Variable Stiffness ◽  
Vibration Absorber ◽  
Frequency Range ◽  
Magnetorheological Elastomer ◽  
Effective Frequency ◽  
Dynamic Vibration Absorber ◽  
Dynamic Vibration ◽  
Narrow Frequency Range ◽  
Dynamic Absorber ◽  
Magneto Rheological

A passive type dynamic vibration absorber offers advantages in reliability and simple constitution, however, the use of the absorber with fixed property is usually limited to harmonically excited case, where the damper is only effective for pre-determined narrow frequency range. Design of the damper following well-known optimal tuning theory could extend the effective frequency range, yet the damping performance remains at a certain amount. In this paper, the stiffness controllable elastomer composite known as Magnetorheological elastomer (MRE) is applied to the dynamic absorber whose natural frequency is tunable by the external magnetic field. MREs are first fabricated and their field-dependent properties are investigated. The MRE is then applied to a dynamic absorber along with stiffness switching scheme so that the vibration of 1-DOF structure is damped more effectively. Investigations show that the vibration of the structure can be fully reduced by the proposed dynamic absorber with variable stiffness functionality.

scholarly journals Tunable Adhesion of a Bio-Inspired Micropillar Arrayed Surface Actuated by a Magnetic Field

2018 ◽  
Vol 86 (1) ◽  
Author(s):  
Xingji Li ◽  
Zhilong Peng ◽  
Yazheng Yang ◽  
Shaohua Chen
Keyword(s):  
Magnetic Field ◽  
Applied Magnetic Field ◽  
Magnetic Particles ◽  
Rotation Angle ◽  
Adhesion Force ◽  
Practical Applications ◽  
Section Shape ◽  
Theoretical Predictions ◽  
Large Elastic Deformation ◽  
The Difference

Bio-inspired functional surfaces attract many research interests due to the promising applications. In this paper, tunable adhesion of a bio-inspired micropillar arrayed surface actuated by a magnetic field is investigated theoretically in order to disclose the mechanical mechanism of changeable adhesion and the influencing factors. Each polydimethylsiloxane (PDMS) micropillar reinforced by uniformly distributed magnetic particles is assumed to be a cantilever beam. The beam's large elastic deformation is obtained under an externally magnetic field. Specially, the rotation angle of the pillar's end is predicted, which shows an essential effect on the changeable adhesion of the micropillar arrayed surface. The larger the strength of the applied magnetic field, the larger the rotation angle of the pillar's end will be, yielding a decreasing adhesion force of the micropillar arrayed surface. The difference of adhesion force tuned by the applied magnetic field can be a few orders of magnitude, which leads to controllable adhesion of such a micropillar arrayed surface. Influences of each pillar's cross section shape, size, intervals between neighboring pillars, and the distribution pattern on the adhesion force are further analyzed. The theoretical predictions are qualitatively well consistent with the experimental measurements. The present theoretical results should be helpful not only for the understanding of mechanical mechanism of tunable adhesion of micropillar arrayed surface under a magnetic field but also for further precise and optimal design of such an adhesion-controllable bio-inspired surface in future practical applications.

Study on Variable Stiffness Mechanism Using Magnetorheological Elastomer

Polymer Korea ◽  
2021 ◽  
Vol 45 (6) ◽  
pp. 948-954
Author(s):  
Dahoon Ahn ◽  
Yujeong Shin ◽  
Kyungwho Choi
Keyword(s):  
Variable Stiffness ◽  
Magnetorheological Elastomer

scholarly journals Lifetime estimate for plasma turbulence

2017 ◽  
Vol 24 (4) ◽  
pp. 673-679 ◽  
Author(s):  
Yasuhito Narita ◽  
Zoltán Vörös
Keyword(s):  
Decay Rate ◽  
Interplanetary Space ◽  
Spatial Scales ◽  
Turnover Time ◽  
Rate Estimate ◽  
Magnetic Field Data ◽  
Theoretical Predictions ◽  
Non Gaussian ◽  
Wigner Spectrum ◽  
Spectrum Model

Abstract. A method is proposed to experimentally determine the intrinsic timescale or a decay rate of turbulent fluctuations. The method is based on the assumption that the Breit–Wigner spectrum model with a non-Gaussian frequency broadening is valid in the data analysis. The decay rate estimate is applied to the multispacecraft magnetic field data in interplanetary space, yielding the decay rate on spatial scales of about 1000 km (about 10 times larger than the ion inertial length), which is higher than the theoretical predictions from the random sweeping timescale of the eddy turnover time. The faster decay of fluctuation components in interplanetary space is interpreted as a realization of plasma physical (and not fluid mechanical) processes.

scholarly journals Application of Adaptive Tuned Magneto-Rheological Elastomer for Vibration Reduction of a Plate by a Variable-Unbalance Excitation

2020 ◽  
Vol 10 (11) ◽  
pp. 3934 ◽  
Author(s):  
Un-Chang Jeong
Keyword(s):  
Vibration Reduction ◽  
Excitation Frequency ◽  
Target Object ◽  
Vibration Absorber ◽  
Magnetorheological Elastomer ◽  
Dynamic Vibration Absorber ◽  
Mass Part ◽  
Dynamic Vibration ◽  
Frequency Excitation ◽  
Magneto Rheological

The present study on vibration reduction in systems wherein the excitation frequency is variable designed and fabricated a magnetorheological elastomer (MRE)-based tunable dynamic vibration absorber and evaluated its performance in an experimental manner. The design of an MRE-based adaptive tuned dynamic vibration absorber (ATDVA) involves designing two parts: stiffness and mass. Before designing the MRE-based ATDVA, this study determined the resonance frequency of a target object for vibration reduction. For the design of the ATDVA’s stiffness part, the thickness of specimens was determined by measuring the rate of variation of the MRE’s shear modulus with respect to the MRE’s thickness. The design of the mass part was optimized using sensitivity analysis and genetic algorithms after the derivation of formulas for its magnetic field and mass. Further, upon the application of an electric current to the MRE, its stiffness was measured so that the stiffness of the designed MRE-based ATDVA could be tuned accordingly. Finally, the vibration-reducing performance of the MRE-based ATDVA was evaluated to determine the applicability of the vibration absorber under the condition of variable-frequency excitation.

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