Active structural acoustic illusions

Abstract

We present active manipulation of the structural vibrations of an elastic body to generate an acoustic illusion. The resultant illusion misrepresents the nature, size and number of objects in the exterior acoustic domain. We demonstrate our technique, herein termed active structural acoustic illusion, using an elastic cylindrical shell. The radial motion of the shell at its cavity resonance frequencies is actively modified using localised mechanical forces. Acoustic illusions are generated to resemble the scattered acoustic field by one or more rigid cylinders of different size and location.

Two-Dimensional Distributed Transmission-Line Models for Broadband Full-Tensor Anisotropic Acoustic Metamaterials Based on Transformation Acoustics

“…Recently, the theory of the 2-D equivalent circuit models for full-tensor anisotropic electromagnetic metamaterials has been extended to acoustic metamaterials [33,34] in order to realize acoustic invisible cloaks [21,[35][36][37][38][39][40][41][42][43][44][45][46][47], acoustic carpet cloaks [33,[48][49][50][51][52][53][54][55][56], or acoustic illusion media [34,[57][58][59][60] based on the concept of transformation acoustics [35]. As is the same in the case of the electromagnetic metamaterials, the conventional design methods have issues like many calculations for designing the unit cell structures or narrowband characteristics, but the models introduced from the electromagnetic metamaterials can solve these simultaneously.…”