English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

A cylindrical rubber fibre subject to twist will also elongate: amanifestation of Poynting's effect in large strain elasticity. Here, weconstruct an analogous treatment for an active rubber fibre actuated via anaxisymmetric pattern of spontaneous distortion. We start by constructing anexact large-deformation solution to the equations of elasticity for such fibresubject to imposed twist and stretch, which reveals spontaneous warping andtwisting of the fibre cross-section absent in passive rubbers. We then computethe corresponding non-linear elastic energy, which encompasses the Poyntingeffect, but is minimized by a finite spontaneous twist and stretch. In thesecond half of the paper, we apply these results to understand thetwist-contraction actuation of nematic elastomer fibres fabricated withdirector-fields that encode helical patterns of contraction on heating. Wefirst consider patterns making a constant angle with respect to the localcylindrical coordinate system (conical spiral director curves) and verify thepredicted spontaneous twist, contraction and cross-section deformation viafinite elements. Secondly, we consider realistic director distributions for theexperimentally reported fibres fabricated by cross-linking while simultaneouslyapplying stretch and twist. Counter-intuitively, we find that maximum actuationtwist is produced by applying a finite optimal twist during fabrication.Finally, we illustrate that spontaneously twisting fibres will coil intospring-like shapes on actuation if the ends are prevented from twistingrelative to each other. Such twist-torsion coupling would allow to make atendril-like "soft-spring" actuator with low force and high linear strokecompared to the intrinsic contraction of the elastomer itself.

Large deformation analysis of spontaneous twist and contraction in nematic elastomer fibres with helical director