Localizing energy in granular materials

TL;DR

This paper introduces a device that localizes and stores energy in a granular chain using soft grains, which generate predictable standing waves regardless of incoming wave timing.

Contribution

It presents a novel method of energy localization in granular materials by embedding soft grains to create predictable standing waves.

Findings

Soft grains produce long-lived standing waves

Energy localization is achieved in the soft region

Standing wave frequencies are predictable

Abstract

A device for absorbing and storing short duration impulses in an initially uncompressed one-dimensional granular chain is presented. Simply stated, short regions of sufficiently soft grains are embedded in a hard granular chain. These grains exhibit long-lived standing waves of predictable frequencies regardless of the timing of the arrival of solitary waves from the larger matrix. We explore the origins, symmetry, and energy content of the soft region and its intrinsic modes.