Effect of the microstructure-dependent nonlocality on acoustic black holes

Abstract

To obtain a well-damped structure, the concept of “acoustic black hole (ABH)” is proposed to trap bending waves at the edge of the wedge shape. However, in the current practice, the remarkable effect of intrinsic lengths is not incorporated. This study aims to reveal the remarkable contribution due to the interplay between intrinsic and extrinsic lengths, which is of fundamental scientific interest. The nonlocal theory is employed to examine the dynamical behaviors of the ABH incorporating the effect of intrinsic lengths. The theoretical model is established for microstructure-dependent power-law plates, and the solution method is developed for analyzing the reflection coefficient of microstructure-dependent power-law plates and bars. It is found that the effect of the microstructure-dependent nonlocality becomes significant and the ABH shows a better absorption of acoustic energy when the nonlocal intrinsic length tends to be lager. Furthermore, the reflection coefficient of traditional works is underestimated. Also, the relationship between the reflection coefficient and wedge truncation length, and frequency is discussed in detail.