AN ACOUSTIC BIONIC METASURFACE BASED ON PLANT SURFACE MICROSTRUCTURES

Compared to classical acoustic materials, acoustic metasurfaces are perfectly used to solve noise problems at low frequencies with their thin thickness and flexibility in design. Due to the geometric restraints, a thinner thickness of metasurfaces usually means a better performance in practical engineering. Therefore, we propose a new kind of metasurface unit structure based on the microstructure of plants surfaces, which can effectively increase the refractive index and thus decrease the thickness of metasurfaces. These units are composed of U-shape tunnels. By arranging the number of U-shape tunnels with the generalized Snell's law, the phase gradient of metasurfaces can be achieved. Then the acoustic performances of the proposed metasurface are analyzed by the finite element method. It is revealed that the designed acoustic metasurface is capable of the same functions as the V-shape metasurface in the previous study but with a 1/3 decrease in thickness. The proposed acoustic metasurface is proved to be suitable for engineering applications and provides a new idea in metasurface unit structure design.