8 research outputs found
Wrinkling hierarchy in constrained thin sheets from suspended graphene to curtains
We show that thin sheets under boundary confinement spontaneously generate a
universal self-similar hierarchy of wrinkles. From simple geometry arguments
and energy scalings, we develop a formalism based on wrinklons, the transition
zone in the merging of two wrinkles, as building-blocks of the global pattern.
Contrary to the case of crumple paper where elastic energy is focused, this
transition is described as smooth in agreement with a recent numerical work.
This formalism is validated from hundreds of nm for graphene sheets to meters
for ordinary curtains, which shows the universality of our description. We
finally describe the effect of an external tension to the distribution of the
wrinkles.Comment: 7 pages, 4 figures, added references, submitted for publicatio
Multiple-length-scale elastic instability mimics parametric resonance of nonlinear oscillators
Spatially confined rigid membranes reorganize their morphology in response to
the imposed constraints. A crumpled elastic sheet presents a complex pattern of
random folds focusing the deformation energy while compressing a membrane
resting on a soft foundation creates a regular pattern of sinusoidal wrinkles
with a broad distribution of energy. Here, we study the energy distribution for
highly confined membranes and show the emergence of a new morphological
instability triggered by a period-doubling bifurcation. A periodic
self-organized focalization of the deformation energy is observed provided an
up-down symmetry breaking, induced by the intrinsic nonlinearity of the
elasticity equations, occurs. The physical model, exhibiting an analogy with
parametric resonance in nonlinear oscillator, is a new theoretical toolkit to
understand the morphology of various confined systems, such as coated materials
or living tissues, e.g., wrinkled skin, internal structure of lungs, internal
elastica of an artery, brain convolutions or formation of fingerprints.
Moreover, it opens the way to new kind of microfabrication design of
multiperiodic or chaotic (aperiodic) surface topography via self-organization.Comment: Submitted for publicatio
Stretchable electronic structures formed of thin films integrated with soft heterogeneous substrate
Stretchable electronic structure comprising one intrinsically fragile thin film integrated on or within a soft heterogeneous substrate. The invention also relates to a process for manufacturing such a structure
In situ tuning the optical properties of a cavity by wrinkling
In this letter we propose an original, in situ, approach to tune the optical properties of an optical cavity, based on the wrinkling of compressed metal/polymer multilayer thin films. This phenomenon is conceptually described, simulated, and experimentally confirmed. The main idea is to use wrinkling to modulate the effective refractive index of the upper interface. This modulation induces a spectral shift of the cavity modes. The work presented here constitutes a first step to the development of stretchable and curved photonics
Hierarchical wrinkling patterns
International audienceThis paper reports a simple and flexible method for generating hierarchical patterns from wrinkling instability. Complex features with gradually changing topographies are generated by using the spontaneous wrinkling of a rigid membrane (titanium) on a soft foundation (polystyrene) compressed via the diffusion of a solvent. We show that the morphology of these unreported wrinkled patterns is directly related to the rheological properties of the polymer layer and the geometry of the diffusion front. Based on these ingredients, we rationalize the mechanism for the formation of hierarchical wrinkling patterns and quantify our experimental findings with a simple scaling theory. Finally, we illustrate the relevance of our structuration method by studying the mechanosensitivity of fibroblasts
Slippery or Sticky Boundary Conditions: Control of Wrinkling in Metal-Capped Thin Polymer Films by Selective Adhesion to Substrates
Wrinkling patterns at the metallized surface of thin polymer films are shown to be sensitive to the sticky or slippery character of the polymer-substrate interface. Existing theoretical models were expanded to specific boundary conditions (adhesive versus slippery) in order to rationalize these observations. Based on this concept, we were able to propose a new and simple method to orient the wrinkles by chemically patterning the substrate with regions of high and low adhesion