Gradient Index Devices for the Simultaneous Focusing of the S0 and A0 Lamb Modes

TL;DR

This paper introduces gradient index devices that enable the simultaneous focusing of S0 and A0 Lamb modes using graded phononic crystals and thickness variations, demonstrated through numerical analysis of flat and Luneburg lenses.

Contribution

It presents a novel approach for controlling multiple Lamb modes simultaneously with gradient index devices, expanding the capabilities of guided wave manipulation.

Findings

Good broadband performance of the designed lenses

Special relationship between refractive indexes for S0 and A0 modes

Potential for designing advanced guided vibrational mode devices

Abstract

Gradient index devices for the simultaneous control of the S 0 and A 0 Lamb modes are presented and numerically analysed. It is found a special relationship between the refractive indexes for these two modes which allows their simultaneous control by means of graded phononic crystals and thickness variations of the plate. A flat gradient index lens and a circular Luneburg lens are designed. Numerical simulations show that the performance of these devices is good for the two modes in a broadband frequency region, and that this approach can be used to design more advanced refractive devices for the total control of guided vibrational modes.