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Bistable eversion of a shell of revolution

FROM:
Keith A. Seffen (1) and Stefano Vidoli (2)
(1) Advanced Structures Group, Department of Engineering, University of Cambridge, UK
(2) Department of Structural and Geotechnical Engineering, Sapienza University of Rome, Italy

“Eversion of bistable shells under magnetic actuation: a model of nonlinear shapes”, Smart Materials and Structures, Vol. 25, No. 6, May 2016,
DOI: 10.1088/0964-1726/25/6/065010

ABSTRACT: We model in closed form a proven bistable shell made from a magnetic rubber composite material. In particular, we incorporate a non-axisymmetrical displacement field, and we capture the nonlinear coupling between the actuated shape and the magnetic flux distribution around the shell. We are able to verify the bistable nature of the shell and we explore its eversion during magnetic actuation. We show that axisymmetrical eversion is natural for a perfect shell but that non-axisymmetrical eversion rapidly emerges under very small initial imperfections, as observed in experiments and in a computational analysis. We confirm the non-uniform shapes of shell and we study the stability of eversion by considering how the landscape of total potential and magnetic energies of the system changes during actuation.

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