Wrinkles, folds and ripplocations: unusual deformation structures of confined elastic sheets at non-zero temperatures

TL;DR

This paper investigates the formation of unusual deformation structures called ripplocations in confined elastic sheets, using simulations to understand their conditions and experimental signatures, revealing new insights into layered solid behavior.

Contribution

It introduces a simulation-based study of ripplocations in layered solids, highlighting their formation conditions and distinguishing features from other deformation structures.

Findings

Ripplocations form under specific load and temperature conditions.

Ripplocations are separated by large free energy barriers from ripples.

Experimental signatures of ripplocations are identified.

Abstract

We study the deformation of a fluctuating crystalline sheet confined between two flat rigid walls as a simple model for layered solids where bonds among atoms {\it within} the same layer are much stronger than those {\it between} layers. When subjected to sufficiently high loads in an appropriate geometry, these solids deform and fail in unconventional ways. Recent experiments suggest that configurations named {\it ripplocations}, where a layer folds backwards over itself, are involved. These structures are distinct and separated by large free energy barriers from smooth {\it ripples} of the atomic layers that are always present at any non-zero temperature. We use Monte Carlo simulation in combination with an umbrella sampling technique to obtain conditions under which such structures form and study their specific experimental signatures.