Band gap and double-negative properties of a star-structured sonic metamaterial

Abstract

Sonic metamaterials have a wide range of applications in wave control and super-resolution imaging, and are favored for their several unique and advantageous properties. However, current double-negative sonic metamaterials have complex structures composed of various materials, which limits their design and application. Thus, we must produce double-negative features using a simple structure of one material. Because of their unique concave configurations and various resonances, star-shaped structures readily form band gaps and show superior material properties. In this study, we designed and simulated star-shaped single-phase metamaterials, considered ideal structures. Our numerical results suggest that these metamaterials have two band gaps as well as double-negative properties over specific frequency ranges. Moreover, we investigated how their band gap and double-negative properties depended on the concave angle.

Band Gaps and Vibration Isolation of a Three-dimensional Metamaterial with a Star Structure

“…The low-frequency band gap of the 3D star structure originated from local resonance. Different from the 2D case, the 3D star structure has more dispersion curves and band gaps in the studied frequency range because of its abundant modes [ 35 , 36 ]. The dispersion curves of both 2D and 3D structures can form a wide band gap in the low frequency range, although the low-frequency band gap of the 3D star structure is lower than that of the 2D.…”

“…The structure is assumed to be infinite and periodic in the x , y, and z directions when calculating the band gap. Furthermore, the Bloch—Floquet periodic boundary conditions were applied along the x , y, and z directions [ 36 ]: where k x , k y , and k z are the components of the Bloch wave vector in the x , y, and z directions, respectively, and a is the lattice constant. The eigenfrequencies and corresponding vibration modes can be obtained by solving Equation (5) in FEM software.…”

“…Meng’s group analyzed the equivalent mechanical behavior and band gap properties of star structures, revealing that the structures contained many broad band gaps at low frequency [ 35 ]. In our previous work, a single-phase solid lens with double-negative index was designed using a star structure [ 36 , 37 ]. However, the above metamaterials usually possess two-dimensional (2D) lattice structures and their band gaps are usually directional, which is not practical.…”

Experimental Investigation of an Acoustic Metamaterial Barrier Design Composed of a Square Prism Within a Hexagonal Recess

“…Manufacturing issues can also be minimized by utilizing designs made out of a single material, reducing manufacturing complications. Acceptable acoustic performance over specific frequency ranges have been shown to be achievable through the use of concave starshaped structures manufactured out of only a single material [20]. Significant noise reduction capabilities can also be achieved through the use of combined heterogeneous double-split hollow sphere which are also simple to manufacture [21].…”

Parameter Optimization for Composite Structures of Microperforated Panel and Porous Metal for Optimal Sound Absorption Performance

“…In the Equations (9) and (10), µ is viscosity coefficient of the air, 1.506 • 10 −5 m 2 • s −1 ; υ is the temperature conduction coefficient of the metal panel, 2.0 • 10 −5 m 2 • s −1 ; ρ is density of the air, 1.21kg • m −3 ; ε is the perforating rate, which can be calculated using Equation (11); k r is the acoustic resistance constant, which can be obtained using Equation 12; ω is still the angular frequency; k m is the acoustic mass constant, which can be derived using Equation (13) [26,38]. In the Equations (12) and (13), k is the perforated panel constant, which can be calculated using Equation (14). d, b, and t represent the diameter of the hole, distance between the neighboring holes, and thickness of the panel, respectively, which are consistent with definitions of structural parameters of the microperforated panel in the Figure 1.…”