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Can you "chop" a mechanical wave?

ahmedettaf's picture

In this paper we highlight several interesting phenomena that may emerge from coupling simple elastic systems like 1d bars. While in compostes we usually focus on wave propagation normal to the stratification direction (composite layers are coupled in series), here we show that extreme attenuation at multiple frequencies may emerge in linear systems that are coupled transversaly. We also introduce a simple device that act as a chopper for mechanical signals.

http://www.nature.com/articles/s41598-017-16364-8

Emergent wave phenomena in coupled elastic bars: from extreme attenuation to realization of elastodynamic switches

Metamaterials with acoustic and elastic band gaps are of great interest to scientists and engineers. Here, we introduce a novel mechanism for emergence of multiple band gaps with extreme attenuation by coupling continuous one-dimensional elastic structures. We show that it is possible to develop extreme attenuation at several frequencies from coupling two homogenous bars of different elastodynamic properties even though each bar individually possesses no such gaps. Moreover, if each bar is a composite on its own, multiple resonant band gaps appear in the compound system which do not exist in either bar. We verify our results by conducting numerical simulations for the elastodynamic response and show that the resonant gaps are efficient in attenuating wave propagation. Furthermore, we show that by carefully tailoring the properties of the coupled bars we may construct elastodynamic signal choppers. These results open a new gate for designing Metamaterial with unique wave modulation properties.

 

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Mike Ciavarella's picture

Ahmed 

   I am not too familiar with this topic, so I can only hope to learn: when you say "Usually this is achieved by coupling the structure to discrete attachments, typically a spring-mass system, to generate a single band gap at the frequency corresponding to the natural frequency of the attachment" can you please provide some references?

Thanks

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