Conformal diffusion acoustic metasurfaces with soft materials for scattering reduction

Planar diffusion acoustic metasurfaces (PDAMs) with rigid materials have attracted much attention due to their ability to redistribute acoustic energy in various directions and to realize acoustic stealth. In this paper, to enhance the adaptability of PDAMs to complex curved surfaces, a conformal diffusion acoustic metasurface (CDAM) with soft materials is proposed to manipulate scattering features, leading to considerable scattering reduction in the specular direction. To realize the proposed CDAM, eight kinds of meta-atoms with phase differences of 45° are introduced. Polydimethylsiloxane (PDMS) is chosen as the material of meta-atoms, which not only has a low modulus but also possesses the ability to deform compliantly with environmental conditions. The simulated results demonstrate that the proposed CDAM can achieve backward scattering reduction of at least 9 dB with bending angles of the CDAM from 0° to 90°, and has potential applications in noise control, acoustic stealth, architectural acoustics, and other relevant applications.