Abstract
Composite materials with engineered band gaps are promising solutions for wave control and vibration mitigation at various frequency scales. Despite recent advances in the design of phononic crystals and acoustic metamaterials, the generation of wide low-frequency band gaps in practically feasible configurations remains a challenge. Here, we present a class of lightweight metamaterials capable of strongly attenuating low-frequency elastic waves, and investigate this behavior by numerical simulations. For their realization, tensegrity prisms are alternated with solid discs in periodic arrangements that we call ‘accordion-like’ meta-structures. They are characterized by extremely wide band gaps and uniform wave attenuation at low frequencies that distinguish them from existing designs with limited performance at low-frequencies or excessively large sizes. To achieve these properties, the meta-structures exploit Bragg and local resonance mechanisms together with decoupling of translational and bending modes. This combination allows one to implement selective control of the pass and gap frequencies and to reduce the number of structural modes. We demonstrate that the meta-structural attenuation performance is insensitive to variations of geometric and material properties and can be tuned by varying the level of prestress in the tensegrity units. The developed design concept is an elegant solution that could be of use in impact protection, vibration mitigation, or noise control under strict weight limitations.
Highlights
The rapidly developing field of elastic metamaterials opens up promising application opportunities, including seismic wave shielding [1, 2, 3], subwavelength imaging [4, 5], noise and vibration abatement [6, 7, 8], protective materials [9, 10], acoustic cloaking [11, 12], just to mention a few examples
We show through analytical calculations and numerical simulations that these structures are characterized by low-frequency band gaps with strong uniform wave attenuation due to the coupling of Bragg scattering and local resonance mechanisms
A common approach based on incorporation of resonators, such as inclusions or pillars, leads to bulky structures and a limited band-gap width with non-uniform Fano-type profile for wave attenuation [17, 25, 26, 27, 28]
Summary
The rapidly developing field of elastic metamaterials opens up promising application opportunities, including seismic wave shielding [1, 2, 3], subwavelength imaging [4, 5], noise and vibration abatement [6, 7, 8], protective materials [9, 10], acoustic cloaking [11, 12], just to mention a few examples (see e.g. reviews [13, 14, 15]). These include three-dimensional and two-dimensional (in-plane wave polarization) structures. By tuning the resonators packing density and increasing its weight, one can reach very low-frequency ranges [25] Another approach consists of the introduction of cavities and a proper redistribution of weight and effective stiffness for the remaining structural parts in order to maximize the band-gap width. The quest continues for simple structured lightweight metamaterials with wide low-frequency band gaps, which can be actively tuned in operating condiconvex &. We assume an either rigid or elastic behavior for interlaying discs and demonstrate that in both cases the meta-structures are capable of generating wide low-frequency band gaps.
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