Harnessing Seeded Geometric Imperfection to Design Cylindrical Shells With Tunable Elastic Postbuckling Behavior

Abstract

Geometric imperfection, known as a detrimental effect on the buckling load of cylindrical shells, has a new role under the emerging trend of using buckling for smart purposes. Eigenshape-based geometries were designed on the shell surface with the aim of tailoring the postbuckling response. Fourteen seeded geometric imperfection (SGI) cylinders were fabricated using polymer-based 3D printing, and their postbuckling responses were numerically simulated with a general-purpose finite element program. Results on the prototyped SGI cylinders showed a tunable elastic postbuckling response in terms of initial and final stiffness, the maximum load drop from mode switching, and the number of snap-buckling events. A response contour and discrete map is presented to show how the number of waves in the axial and circumferential directions in the seeded eigenshape imperfection can control the elastic postbuckling response. SGI cylinders provide diverse design opportunities for controllable unstable response and are good candidates for use in smart and adaptive materials/structures.

On the role of localizations in buckling of axially compressed cylinders

“…If this is indeed the case, then tailoring stress fields in a particular (non-uniform) way should result in better correlations between predictions and experiments; the reasoning being that the symmetry of a circumferentially uniform stress field can be broken by a larger set of imperfections than an a priori tailored, non-uniform stress field. This could explain the recent success of researchers in deterministically tailoring and predicting the precise post-buckling behaviour of shells with engineered imperfections [8,54] and also with varying material properties [55]. Especially, the latter work may provide an impetus for future work on tailoring cylinders with modern materials technology, such as tow-steered composites.…”

Harnessing energy landscape exploration to control the buckling of cylindrical shells

“…This enables us to design buckling responses by locally thickening or thinning the cylinder, complementary to experimental realisation; see for example, refs. [39][40][41] . We demonstrate two examples of landscape biasing, by first biasing against a target transition state, and then biasing for a target minimum.…”

“…This is achieved by making local modifications to the elastic spring constants in the triangular lattice model to simulate thickness modifications. Thus, the knowledge of the energy landscape proves highly complementary to experimental processes aimed at exerting postbuckling control [39][40][41] . We demonstrate the principle of landscape biasing by first showing how biasing against the unbuckled-single dimple transition state produces a 20% increase in buckling resistance of the unbuckled cylinder for a 1% increase in mass.…”

Programmable 3D Self‐Folding Structures with Strain Engineering

“…For example, the opening and closing of pine cones are attributed to the tissue's self‐bending, which undergoes three states of humidity‐driven deformation. [ 6 ] As these morphological changes in nature result from the variation of the surrounding environment, it is desirable to mimic these natural examples to fabricate multilayered structures that can spontaneously respond to various external stimuli, such as temperature, pH, biochemical enzymes, magnetic fields, and solvent composition, [ 11–14 ] which can find a variety of applications, such as semiconductor nanotubes, [ 15–18 ] soft robotics, [ 19–22 ] snapping surface, [ 23 ] and micro/nanoelectromechanical systems. [ 24–26 ]…”