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. 2015 Dec 16;5:18373. doi: 10.1038/srep18373

Figure 1. Deformation mechanism of dimpled elastic sheets.

Figure 1

(a) The building block of the proposed auxetic material comprises a flat sheet dented with a spherical dimple. (b) Numerical results showing the deformation under uniaxial tension of an elastic sheet with a square array of 20 × 20 dimples dented on one side of the sheet (we assume ψ = 75%, h/r = 0.5 =  and t/r = 0.08). The analysis reveals that this structure bends out of plane and contracts laterally. (c) The out-of-plane bending of the structure can be prevented by denting the dimples on both side of the flat sheet to form a checkerboard pattern. Such structure expands when stretched and, thus, is characterized by negative Poisson’s ratio. Note that the results shown in (b,c) have been magnified 600 times to better visualize the deformations.