Strongly nonlinear wave dynamics in a chain of polymer coated beads

TL;DR

This paper investigates strongly nonlinear wave behavior in a chain of polymer-coated steel beads, demonstrating unique phononic crystal properties and comparing experimental solitary wave dynamics with uniform steel bead chains.

Contribution

It introduces a novel strongly nonlinear phononic crystal system using Parylene-C coated beads and analyzes wave propagation and fracture behavior under impact conditions.

Findings

Demonstrated strongly nonlinear solitary waves in coated bead chains

Compared wave dynamics with uniform steel bead chains

Observed coating fracture at high impact amplitudes

Abstract

Strongly nonlinear phononic crystals were assembled from a chain of Parylene-C coated steel spheres in a polytetrafluoroethylene (PTFE) holder. This system exhibits strongly nonlinear properties and extends the range of materials supporting "sonic vacuum" type behavior. The combination of a high density core and a soft (low elastic modulus) coating ensures a relatively low velocity of wave propagation. The beads contact interaction caused by the deformation of the Parylene coating can be described as classical nonlinear Hertz theory despite the viscoelastic nature of the polymer and the high strain rate deformation of the contact area. Strongly nonlinear solitary waves excited by impacts were investigated experimentally and compared to chains composed of uniform steel beads. Fracture of the polumer coating was detected under relatively large pulse amplitude.