@article {63,
	title = {Rods coiling about a rigid constraint: Helices and perversions},
	journal = {Proceedings of the Royal Society A},
	volume = {477},
	year = {2021},
	pages = {20200817},
	abstract = {<p align="justify">Mechanical instabilities can be exploited to design innovative structures, able to change their shape in the presence of external stimuli. In this work, we derive a mathematical model of an elastic beam subjected to an axial force and constrained to smoothly slide along a rigid support, where the distance between the rod midline and the constraint is fixed and finite. Using both theoretical and computational techniques, we characterize the bifurcations of such a mechanical system, in which the axial force and the natural curvature of the beam are used as control parameters. We show that, in the presence of a straight support, the rod can deform into shapes exhibiting helices and perversions, namely transition zones connecting together two helices with opposite chirality. The mathematical predictions of the proposed model are also compared with some experiments, showing a good quantitative agreement. In particular, we find that the buckled configurations may exhibit multiple perversions and we propose a possible explanation for this phenomenon based on the energy landscape of the mechanical system.</p>},
	keywords = {bifurcation theory, elastic rods, finite-element simulations, helices, perversions, weakly nonlinear analysis},
	doi = {/10.1098/rspa.2020.0817},
	author = {Davide Riccobelli and Giovanni Noselli and Antonio DeSimone}
}
@article {59,
	title = {Mechanics of axisymmetric sheets of interlocking and slidable rods},
	journal = {Journal of the Mechanics and Physics of Solids},
	volume = {141},
	year = {2020},
	pages = {103969},
	abstract = {<p align="justify">In this work, we study the mechanics of metamaterial sheets inspired by the pellicle of Euglenids. They are composed of interlocking elastic rods which can freely slide along their edges. We characterize the kinematics and the mechanics of these structures using the special Cosserat theory of rods and by assuming axisymmetric deformations of the tubular assembly. Through an asymptotic expansion, we investigate both structures that comprise a discrete number of rods and the limit case of a sheet composed by infinitely many rods. We apply our theoretical framework to investigate the stability of these structures in the presence of an axial load. Through a linear analysis, we compute the critical buckling force for both the discrete and the continuous case. For the latter, we also perform a numerical post-buckling analysis, studying the non-linear evolution of the bifurcation through finite elements simulations.\&nbsp;</p>},
	keywords = {Biomimetic structures, Elastic structures, Helical rods, Mechanical instabilities, Metamaterials, Post-buckling analysis},
	doi = {10.1016/j.jmps.2020.103969},
	author = {Davide Riccobelli and Giovanni Noselli and Marino Arroyo and Antonio De Simone}
}
