A reconfigurable magnetorheological elastomer acoustic metamaterial

2020 ◽  
Vol 117 (10) ◽  
pp. 104102
Author(s):  
C. L. Willey ◽  
V. W. Chen ◽  
K. J. Scalzi ◽  
P. R. Buskohl ◽  
A. T. Juhl
Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 125
Author(s):  
Yuqi Jin ◽  
Yurii Zubov ◽  
Teng Yang ◽  
Tae-Youl Choi ◽  
Arkadii Krokhin ◽  
...  

An acoustic metamaterial superlattice is used for the spatial and spectral deconvolution of a broadband acoustic pulse into narrowband signals with different central frequencies. The operating frequency range is located on the second transmission band of the superlattice. The decomposition of the broadband pulse was achieved by the frequency-dependent refraction angle in the superlattice. The refracted angle within the acoustic superlattice was larger at higher operating frequency and verified by numerical calculated and experimental mapped sound fields between the layers. The spatial dispersion and the spectral decomposition of a broadband pulse were studied using lateral position-dependent frequency spectra experimentally with and without the superlattice structure along the direction of the propagating acoustic wave. In the absence of the superlattice, the acoustic propagation was influenced by the usual divergence of the beam, and the frequency spectrum was unaffected. The decomposition of the broadband wave in the superlattice’s presence was measured by two-dimensional spatial mapping of the acoustic spectra along the superlattice’s in-plane direction to characterize the propagation of the beam through the crystal. About 80% of the frequency range of the second transmission band showed exceptional performance on decomposition.


2021 ◽  
pp. 107754632110253
Author(s):  
Emiliano Rustighi ◽  
Diego F Ledezma-Ramirez ◽  
Pablo E Tapia-Gonzalez ◽  
Neil Ferguson ◽  
Azrul Zakaria

This article proposes a simple physical-based model to describe and predict the performance of axially compressed magnetorheological elastomer cylinders used as vibration and shock absorbers. The model describes the magnetorheological elastomer macroscopic stiffness changes because of an externally applied magnetic field from a microscopic composite cell of silicone rubber and carbonyl iron particle. Despite neglecting the material hyperelasticity, anisotropy and adjacent magnetic interaction, the model describes effectively the effect of the magnetic field on the macroscopic modulus of elasticity. The changes in the mechanical properties with the induced magnetic field are measured on samples of different particle concentration based on volume percentage, that is, 10 and 30 percent concentration of iron particles in a silicone rubber matrix. The manufacturing process of the samples is detailed, as well as the experimental validation of the effective stiffness change under a magnetic field in terms of transmissibility and mobility testing. However, the prediction seems to be limited by the linear elastic material model. Predictions and measurements are compared, showing that the model is capable of predicting the tunability of the dynamic/shock absorber and that the proposed devices have a possible application in the reduction of mechanical vibrations.


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