Measuring the lift-off force for d cones*

The buckling of slender objects is of considerable current interest [1] [2]. One example is the formation of d cones: a normal force applied to the center of a thin circular elastic disk supported by the rim of a hollow right circular cylinder at first results in a cylindrically symmetric cone. At a critical force, the cone buckles, and a portion of the disk lifts from the rim, forming a d cone. We have measured the force as function of displacement of the cone center for Mylar disks, and determined the lift-off force as function of radius and thickness. The results follow a simple scaling law.

[1 K. Seffen, Fundamental conical defects: The d-cone, its e-cone, and its p-cone, Phys. Rev. E. 94, 013002 (2016).
[2] D. Holmes, et al., Buckling of geometrically confined shells, Soft Matter, 15, 1215, 2019