We investigate the normal modes of a developable cone singularity as observed in a circular sheet supported by a rigid circular frame and pushed at its center. When the center of the sheet is in addition submitted to a sinusoidal forcing, two types of bending modes, named here rolling and tilt modes, are parametrically excited. The rolling mode is an angular oscillation of the concave sector of the developable cone structure. If the amplitude of vibration is high enough, the rolling mode amplitude increases dramatically giving rise to both a continuous rotation of the concave sector and a material angular displacement of the sheet, similar to that produced by a moving wrinkle in a carpet.
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http://dx.doi.org/10.1103/PhysRevLett.99.254301 | DOI Listing |
Phys Rev E
September 2024
Advanced Structures Group, Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom.
When a simply supported thin disk is indented by a centrally applied point force, it buckles out-of-plane to form a shape dominated by two conical portions: a uniform region indenting against the support, interrupted by a smaller elevated portion detached from the support, altogether known as a "developable cone" or d-Cone. If a central circular region of the disk is clamped instead, then the buckling complexion changes markedly: The indenting region is interspersed with several detached and elevated cones, now "truncated," where their number depends on the clamping extent as well as the radius of the circular simple support. Studies of d-Cone kinematics often consider its shape as an analogous vertex, which forms by folding along hinge lines separating triangular facets.
View Article and Find Full Text PDFPhys Rev E
November 2023
Advanced Structures Group, Civil Engineering Building, JJ Thomson Avenue, University of Cambridge, Cambridge CB3 0FA, United Kingdom.
We present a scheme for calculating the shape of two well-known conical motifs: the d-Cone and the e-Cone. Each begins as a thin, flat disk, before buckling during loading into a deformed shape with distinctive, asymmetrical conical features and a localised apex. Various deformed equilibrium models rightly assume a developable shape, with a particular focus on determining how much of the disk detaches from how it is supported during buckling; they are, nevertheless, extensively curated analytically, and must confront (some, ingeniously) the question of singular, viz.
View Article and Find Full Text PDFPhys Rev E
September 2023
Department of Mechanical Engineering, Boston University, Boston, Massachusetts 02215, USA.
Thin sheets respond to confinement by smoothly wrinkling or by focusing stress into small, sharp regions. From engineering to biology, geology, textiles, and art, thin sheets are packed and confined in a wide variety of ways, and yet fundamental questions remain about how stresses focus and patterns form in these structures. Using experiments and molecular dynamics simulations, we probe the confinement response of circular sheets, flattened in their central region and quasistatically drawn through a ring.
View Article and Find Full Text PDFPhys Rev E
February 2018
Advanced Structures Group Laboratory, Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom.
In their study, Duncan and Duncan [Proc. R. Soc.
View Article and Find Full Text PDFPhys Rev E Stat Nonlin Soft Matter Phys
February 2015
James Franck Institute, The University of Chicago, 929 E. 57th St., Chicago, Illinois 60637, USA.
We examine the shape change of a thin disk with an inserted wedge of material when it is pushed against a plane, using analytical, numerical, and experimental methods. Such sheets occur in packaging, surgery, and nanotechnology. We approximate the sheet as having vanishing strain, so that it takes a conical form in which straight generators converge to a disclination singularity.
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