scholarly journals Elastic metamaterials for independent realization of negativity in density and stiffness

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Joo Hwan Oh ◽  
Young Eui Kwon ◽  
Hyung Jin Lee ◽  
Yoon Young Kim
Keyword(s):  
Independent Realization ◽  
Elastic Metamaterials

scholarly journals Numerical Modelling and Optimization of Two-Dimensional Phononic Band Gaps in Elastic Metamaterials with Square Inclusions

2021 ◽  
Vol 11 (7) ◽  
pp. 3124
Author(s):  
Alya Alhammadi ◽  
Jin-You Lu ◽  
Mahra Almheiri ◽  
Fatima Alzaabi ◽  
Zineb Matouk ◽  
...  
Keyword(s):  
Elastic Wave ◽  
Tungsten Carbide ◽  
Composite Structure ◽  
Elastic Waves ◽  
Wave Attenuation ◽  
Low Frequency ◽  
Filling Fraction ◽  
Carbide Composite ◽  
Elastic Metamaterials ◽  
Tungsten Carbide Composite

A numerical simulation study on elastic wave propagation of a phononic composite structure consisting of epoxy and tungsten carbide is presented for low-frequency elastic wave attenuation applications. The calculated dispersion curves of the epoxy/tungsten carbide composite show that the propagation of elastic waves is prohibited inside the periodic structure over a frequency range. To achieve a wide bandgap, the elastic composite structure can be optimized by changing its dimensions and arrangement, including size, number, and rotation angle of square inclusions. The simulation results show that increasing the number of inclusions and the filling fraction of the unit cell significantly broaden the phononic bandgap compared to other geometric tunings. Additionally, a nonmonotonic relationship between the bandwidth and filling fraction of the composite was found, and this relationship results from spacing among inclusions and inclusion sizes causing different effects on Bragg scatterings and localized resonances of elastic waves. Moreover, the calculated transmission spectra of the epoxy/tungsten carbide composite structure verify its low-frequency bandgap behavior.

Selective Wave Filtering in Time-Modulated Elastic Metamaterials

2018 ◽  
Author(s):  
Yiwei Xia ◽  
Giuseppe Trainiti ◽  
Alper Erturk ◽  
Massimo Ruzzene
Keyword(s):  
Single Port ◽  
Negative Capacitance ◽  
Time Modulation ◽  
Piezoelectric Patch ◽  
Flat Bands ◽  
Elastic Metamaterials ◽  
In Series ◽  
Port System ◽  
Opening And Closing ◽  
Time Periodic

We implement periodic stiffness time-modulation in a beam with piezoelectric patches and switchable shunted negative capacitance. The shunted negative capacitance circuits, connected in series with each piezoelectric patch through a switch, soften the structure. By alternatively opening and closing the switch, the beam’s stiffness effectively oscillates periodically between two values. We present a simplified theoretical model of time-periodic beams and describe the occurrence of flat bands in the dispersion diagrams. We show that a narrowband reflection from a time-modulated domain can be obtained for a broadband incident wave, hence qualifying the modulated domain as a single-port system with tunable response. We validate our theoretical findings by comparing time-domain simulations with experimental measurements of transient wavefields through scanning Doppler laser vibrometry.

A design of active elastic metamaterials with negative mass density and tunable bulk modulus

2018 ◽  
Vol 230 (3) ◽  
pp. 1003-1008 ◽  
Author(s):  
Sheng Sang ◽  
Anwer Mhannawee ◽  
Ziping Wang
Keyword(s):  
Bulk Modulus ◽  
Mass Density ◽  
Negative Mass ◽  
Elastic Metamaterials
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