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Wrinkle motifs in thin films.

Budrikis Z, Sellerio AL, Bertalan Z, Zapperi S - Sci Rep (2015)

Bottom Line: 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.Our simulations uncover the generic behaviour of avoiding wrinkle pairs that should be valid at all scales.

View Article: PubMed Central - PubMed

Affiliation: ISI Foundation, Via Alassio 11/c, 10126 Torino, Italy.

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.

No MeSH data available.


Related in: MedlinePlus

Wrinkle tips generate anisotropic stress fields.(a) Trace of the stress tensor from a single wrinkle, showing tension behind the tip and compression in front, concentrated at the tip. The scale bar represents 100 nm. (b) Slices of the stress trace parallel and perpendicular to the wrinkle direction, as indicated by red and blue lines in panel (a). (c) σxx + σyy for an infinite sheet with an idealized wrinkle imposed. (d) Slices of σxx + σyy parallel and perpendicular to the wrinkle direction, as indicated by red and blue lines in panel (c). For clarity, in panels (a) and (c) the interiors of the wrinkles, defined by a height threshold of 2 Å, are not shown.
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f3: Wrinkle tips generate anisotropic stress fields.(a) Trace of the stress tensor from a single wrinkle, showing tension behind the tip and compression in front, concentrated at the tip. The scale bar represents 100 nm. (b) Slices of the stress trace parallel and perpendicular to the wrinkle direction, as indicated by red and blue lines in panel (a). (c) σxx + σyy for an infinite sheet with an idealized wrinkle imposed. (d) Slices of σxx + σyy parallel and perpendicular to the wrinkle direction, as indicated by red and blue lines in panel (c). For clarity, in panels (a) and (c) the interiors of the wrinkles, defined by a height threshold of 2 Å, are not shown.

Mentions: To understand how wrinkle interactions affect their shape, we characterize the stresses induced by wrinkles, using the trace of the stress tensor Tr(σ) = σxx + σyy + σzz. Unlike, e.g, tensile fracture, where hoop stress σθθ determines crack propagation29, the symmetry of wrinkle propagation makes the isotropic stress the relevant quantity. We first consider a single wrinkle. As shown in Fig. 3, stresses emanating from the tip of a wrinkle are compressive (Tr(σ) < 0). The wrinkle grows via buckling of the sheet, and deformation occurs primarily as bending rather than stretching which is highly unfavourable for graphene.


Wrinkle motifs in thin films.

Budrikis Z, Sellerio AL, Bertalan Z, Zapperi S - Sci Rep (2015)

Wrinkle tips generate anisotropic stress fields.(a) Trace of the stress tensor from a single wrinkle, showing tension behind the tip and compression in front, concentrated at the tip. The scale bar represents 100 nm. (b) Slices of the stress trace parallel and perpendicular to the wrinkle direction, as indicated by red and blue lines in panel (a). (c) σxx + σyy for an infinite sheet with an idealized wrinkle imposed. (d) Slices of σxx + σyy parallel and perpendicular to the wrinkle direction, as indicated by red and blue lines in panel (c). For clarity, in panels (a) and (c) the interiors of the wrinkles, defined by a height threshold of 2 Å, are not shown.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4355740&req=5

f3: Wrinkle tips generate anisotropic stress fields.(a) Trace of the stress tensor from a single wrinkle, showing tension behind the tip and compression in front, concentrated at the tip. The scale bar represents 100 nm. (b) Slices of the stress trace parallel and perpendicular to the wrinkle direction, as indicated by red and blue lines in panel (a). (c) σxx + σyy for an infinite sheet with an idealized wrinkle imposed. (d) Slices of σxx + σyy parallel and perpendicular to the wrinkle direction, as indicated by red and blue lines in panel (c). For clarity, in panels (a) and (c) the interiors of the wrinkles, defined by a height threshold of 2 Å, are not shown.
Mentions: To understand how wrinkle interactions affect their shape, we characterize the stresses induced by wrinkles, using the trace of the stress tensor Tr(σ) = σxx + σyy + σzz. Unlike, e.g, tensile fracture, where hoop stress σθθ determines crack propagation29, the symmetry of wrinkle propagation makes the isotropic stress the relevant quantity. We first consider a single wrinkle. As shown in Fig. 3, stresses emanating from the tip of a wrinkle are compressive (Tr(σ) < 0). The wrinkle grows via buckling of the sheet, and deformation occurs primarily as bending rather than stretching which is highly unfavourable for graphene.

Bottom Line: 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.Our simulations uncover the generic behaviour of avoiding wrinkle pairs that should be valid at all scales.

View Article: PubMed Central - PubMed

Affiliation: ISI Foundation, Via Alassio 11/c, 10126 Torino, Italy.

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.

No MeSH data available.


Related in: MedlinePlus