# Prestress tuning of negative refraction and wave channeling from flexural sources

## TL;DR

This paper demonstrates how prestress tuning in elastic grids enables control over wave phenomena like negative refraction and signal channeling, with potential for adaptable vibration manipulation.

## Contribution

It introduces a novel method of using prestress states to dynamically tune wave propagation and localization in elastic structures, including the use of pulsating moments.

## Key findings

- Achieved total reflection and negative refraction through prestress tuning.
- Demonstrated flat lens and topologically localized modes.
- System tunability applies across a broad wavelength range.

## Abstract

The quest for wave channeling and manipulation has driven a strong research effort on topological and architected materials, capable of propagating localized electromagnetical or mechanical signals. With reference to an elastic structural grid, which elements can sustain both axial and flexural deformations, it is shown that material interfaces can be created with structural properties tuned by prestress states to achieve total reflection, negative refraction, and strongly localized signal channeling. The achievement of a flat lens and topologically localized modes is demonstrated and tunability of the system allows these properties to hold for a broad range of wavelengths. An ingredient to obtain these effects is the use, suggested here and never attempted before, of concentrated pulsating moments. The important aspect of the proposed method is that states of prestress can be easily removed or changed to tune with continuity the propagational characteristics of the medium, so that a new use of vibration channeling and manipulation is envisaged for elastic materials.