A passively tunable non-resonant acoustic metamaterial lens for selective ultrasonic excitation

TL;DR

This paper introduces a passively tunable non-resonant acoustic metamaterial lens that enables selective ultrasonic excitation and beam-steering in structures, using embedded design principles and validated through numerical and experimental methods.

Contribution

The work presents a novel embedded non-resonant acoustic metamaterial lens that achieves directional ultrasonic excitation with a single transducer, unlike existing technologies.

Findings

Numerical analysis confirms the lens's ability to steer ultrasonic beams.

Experimental validation demonstrates effective beam-forming on an aluminum plate.

The lens design enables dynamic coupling of ultrasonic waveguides at specific frequencies.

Abstract

In this paper, we present an approach to ultrasonic beam-forming and beam-steering in structures based on the concept of embedded non-resonant acoustic metamaterial lenses. The lens design exploits the principle of acoustic drop-channel which enables the dynamic coupling of multiple ultrasonic waveguides at selected frequencies. In contrast with currently available technology, the embedded lens allows generating directional excitation by means of a single ultrasonic transducer. The lens design and performance are numerically investigated by using Plane Wave Expansion and Finite Difference Time Domain techniques applied to bulk structures. Then, the design is experimentally validated on a thin aluminum plate where the lens is implemented by through-holes. The dynamic response of the embedded lens is estimated by reconstructing, via Laser Vibrometry, the velocity field induced by a piezoelectric shaker source.