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. 2013 Jul 22;110(32):12893–12898. doi: 10.1073/pnas.1301695110

Fig. 1.

Fig. 1.

Our model system: a circular, crystalline sheet of radius W adhered to a spherical substrate of radius Inline graphic. Colors of contours indicate the level of hoop stress: tension (red), vanishing stress (white), and compression (blue). (A) The rest (stress-free) state of the sheet is shown above a schematic of the confinement geometry. (B) The axisymmetric state for confinement Inline graphic: The hoop stress is compressive in a confined zone of width Inline graphic near the perimeter. (C) The wrinkle pattern, in which the hoop stress vanishes in the confined zone as the bendability Inline graphic. Wrinkles require small deformation of the spherical substrate with the attached sheet. (D) The scar pattern that maintains the imposed spherical shape, in which the stress approaches a profile identical to that of C as the defectability Inline graphic. The shaded area indicates the range beyond which dislocation interactions are effectively screened by the boundary Inline graphic. (E and F) The stress fields of the axisymmetric, unstable state (B) and the compression-free state (C and D). (G and H) Profiles of the axisymmetric and compression-free stresses for a negative-curvature (saddle) substrate, in which both radial and hoop stresses collapse in the center of the sheet.