Huang, JiangshuiLiu, JiaKroll, BenediktBertoldi, KatiaClarke, David2012-07-162012Huang, Jiangshui, Jia Liu, Benedikt Kroll, Katia Bertoldi, and David R. Clarke. 2012. Spontaneous and deterministic three-dimensional curling of pre-strained elastomeric bi-strips. Soft Matter 8(23): 6291-6300.1744-683X1744-6848http://nrs.harvard.edu/urn-3:HUL.InstRepos:9177225Three dimensional curls (“hemi-helices”) consisting of multiple, periodic and alternating helical sections of opposite chiralities, separated by perversions, are one of a variety of complex shapes that can be produced by a simple generic process consisting of pre-straining one elastomeric strip, joining it side-by-side to another and then releasing the bi-strip. The initial wavelength of the hemi-helix and the number of perversions are determined by the strip cross-section, the constitutive behavior of the elastomer and the value of the pre-strain. The hemi-helix has no net twist. Topologically, the perversions separate regions of the hemi-helix deforming principally by bending from those where twisting dominates.en-UStendril perversionJournal Article2012-07-1610.1039/c2sm25278c