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Wrinkling Crystallography on Curved Surfaces

Miha Brojan (MIT), Denis Terwagne (Massachusetts Institute of Technology), Pedro Reis (MIT)

Soft Materials and Structures

Mon 9:00 - 10:30

Barus-Holley 158

We present results on an experimental analysis of the morphology of wrinkling patterns on curved surfaces. Our experimental hemispherical samples are fabricated using rapid prototyping techniques and consist of a thin-stiff shell adhered to a soft-thick substrate, both made out of silicone-based rubbers. Pressurizing an inner spherical air cavity enables us to compress our samples, thereby morphing the outer thin shell from its initially smooth configuration into a wrinkled state. A variety of patterns with different morphologies can be observed depending on the combination of geometric and material properties of the samples. We focus our attention on the specific pattern mode of hexagonal-like dimples, which we characterize by analyzing their surface profile using a digital 3D scanner. Through digital image processing, we skeletonize these patterns by identifying both the location of the ridges and determining the positions of the dimples. We give emphasis to the effect of curvature on the morphology and topology of these wrinkled patterns and focus on the tiling of the wrinkling units and the statistics of defects. Our results are contrasted with other crystalline planar and curved systems.