Manipulation of acoustic waves using a functionally graded material and process for making the same

Abstract

A device for manipulation of acoustic waves is provided, comprising a functionally-graded material for interposing between a source of the acoustic waves and a target, which may be a detector of manipulated acoustic waves. The functionally-graded material has a gradient in acoustic wave velocity which is obtained by the generation of a gradient in at least one of the following properties: elastic modulus, Poisson's ratio, and density, that is perpendicular to a direction of propagation of the acoustic waves. The gradient is axial. Biaxial acoustic velocity gradients may be used for focusing/waveguiding (high-low-high) or dispersing (low-high-low), while monoaxial acoustic velocity gradients may be used for wave steering. Also in accordance with the present invention, a method of making the device is provided, comprising: (a) providing the source of acoustic waves; (b) providing the target for acoustic waves, e.g., detector of manipulated acoustic waves; (c) providing the functionally-graded material having a gradient in at least one material property; and (d) interposing the functionally-graded material between the source of acoustic waves and the target for acoustic waves such that the gradient is perpendicular to a direction of propagation of the acoustic waves. The functionally-graded material so provided can be used to manipulate, i.e., focus, disperse, steer, waveguide acoustic waves for applications such as, acoustoelectronics, acoustooptics, SONAR, ultrasonic imaging, non-destructive testing (NDT), etc.