Twisters: An analogy of bilayers for twisting

Benders, such as bilayers, are well-known shape-changing structures which bend upon activation by a stimulus, such as temperature. The objective of this contribution is to propose new shape-changing rod-like structures, referred to as twisters, which twist upon activation. A simple biomimetic design...

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Bibliographic Details
Published in:Journal of the mechanics and physics of solids 2020-01, Vol.134, p.103742, Article 103742
Main Authors: Turcaud, Sébastien, Thorin, Anders, Bréchet, Yves, Fratzl, Peter, Dunlop, John WC
Format: Article
Language:English
Subjects:
Activation
Bending machines
Bifurcations
Biomimetics
Computer simulation
Engineering Sciences
Finite element method
Kinematics
Mechanical engineering
Mechanics
Physics
Simulation
Solid mechanics
State variable
Structural mechanics
Twisting
Vibrations
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Summary:Benders, such as bilayers, are well-known shape-changing structures which bend upon activation by a stimulus, such as temperature. The objective of this contribution is to propose new shape-changing rod-like structures, referred to as twisters, which twist upon activation. A simple biomimetic design principle based on symmetry considerations is proposed. FEM simulations show that the proposed design does feature a twisting instability in reaction to an increasing stimulus. A simpler generic mechanical model with two state variables, whose kinematics is inspired from the FEM simulations, is then proposed and its governing equations are derived analytically. As in the FEM simulations, such twisters are shown to first stretch as the stimulus increases until a bifurcation is reached, then, they undergo a mixed stretching–twisting regime. An accurate approximation of the bifurcation point is derived and serves as a guideline for the design of twisters in accordance with chosen specifications. Results are illustrated using twisters with three different behaviours.
ISSN:0022-5096
1873-4782
DOI:10.1016/j.jmps.2019.103742