Plastic ridge formation in a compressed thin amorphous film

TL;DR

This paper reveals that surface ridge formation in compressed amorphous thin films results from localized plastic events that self-organize, rather than elastic instabilities, indicating a generic behavior in glassy materials under compression.

Contribution

It uncovers a new mechanism of ridge formation driven by correlated plastic activity, contrasting with traditional elastic instability theories.

Findings

Ridges form without elastic pattern instability

Plastic activity self-organizes into parallel ridges

Phenomenon is likely universal in glassy thin films

Abstract

We demonstrate that surface morphogenesis in compressed thin films may result from spatially correlated plastic activity. A soft glassy film strongly adhering to a smooth and rigid substrate and subjected to uniaxial compression, indeed, does not undergo any global elastic pattern-forming instability, but responds plastically via localized burst events that self-organize, leading to the emergence of a series of parallel ridges transverse to the compression axis. This phenomenon has been completely overlooked, but results from common features of the plastic response of glasses, hence should be highly generic for compressed glassy thin films.