Wrinkle motifs in thin films

Abstract

On length scales from nanometres to metres, partial adhesion of thin films with substrates generates a fascinating variety of patterns, such as ‘telephone cord’ buckles, wrinkles, and labyrinth domains. Although these patterns are part of everyday experience and are important in industry, they are not completely understood. Here, we report simulation studies of a previously-overlooked phenomenon in which pairs of wrinkles form avoiding pairs, focusing on the case of graphene over patterned substrates. By nucleating and growing wrinkles in a controlled way, we characterize how their morphology is determined by stress fields in the sheet and friction with the substrate. Our simulations uncover the generic behaviour of avoiding wrinkle pairs that should be valid at all scales.

Filiform corrosion as a pressure-driven delamination process

“…Self-avoidance in delamination patterns has been predicted through numerical simulations. 60 The extension of this study to pressure-driven delamination would be necessary to confirm self-avoidance for filiforms and could perhaps explain the quasi-specular reflection reported in Section 2.2. Notice also that, using eqn (29) and (30), the total energy can now be written as U tot = À4LWg/7, where W is given by (30).…”

Strain Modulation of Graphene by Nanoscale Substrate Curvatures: A Molecular View

“…This is possibly due to a balance between the tension force in Gr and the friction force between Gr and NS. 28 Phenomenologically, this fixed width of wrinkles is responsible for the evolution of Gr deformation patterns as the NS size increases: for Gr-20, the NSs are too small to generate wrinkles, and therefore, the Gr experiences smooth deformations ( Figure 1f); in Gr-50, the wrinkle width is similar to the diameter of the adhered Gr area on each NS, facilitating the propagation of wrinkles and the formation of stripy domains, where each NS is typically connected to two of its six neighboring spheres via Gr wrinkles ( Figure 1g); for larger NSs, the Gr adhesion diameter is larger than the wrinkle width, giving rise to more wrinkles (each NS is typically surrounded by three to six wrinkles connecting to adjacent NSs) ( Figure 1h,i).…”

Mastering the Wrinkling of Self-supported Graphene

“…The observation of ‘avoiding pairs’ of wrinkles in the random areas corresponds well with the simulations of Budrikis et al . 63 , who simulated the conditions under which two wrinkles formed on two separated objects can join or form the ‘avoiding pair’. Comparing the geometry of our system with the simulations, the length of the wrinkle created on individual pillars with no external anisotropic effects should reach almost 140 nm, and prevents joining with the wrinkle formed on the NN pillar (following the notation in the manuscript 63 , Fig.…”