ELASTIC BUCKLING OF 2D CELLULAR STRUCTURES

Stephen Willshaw, Tom Mullin, György Károlyi

Abstract

Recent experimental and numerical studies have uncovered a fascinating pattern switching mechanism in 2D cellular structures under uniaxial compression. A square lattice of initially circular voids transforms into an array of mutually orthogonal ellipses as a result of a buckling instability triggered at a critical stress value. This reversible, repeatable phenomenon occurs globally throughout the sample and has been observed at the sub-micron level. This has led to the manufacture of tunable optical devices which utilise this geometric switching to alter photonic band gaps in periodic structures. The switch also causes a counter-intuitive auxetic effect.<BR />Traditional studies of 2D cellular structures focus on the role of void size relative to the lattice on the response of these structures to compression. Here, we present the results of experiments which probe the influence of this parameter on 2D cellular structures possessing circular voids. These findings are compared with a simple spring-link model which uses potential energy minimization techniques to predict the collapse of the structure, and hence the onset of pattern switching, as a result of uni-axial compression.

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IMEKO-YSESM-2011-ea45.pdf

DOI

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IMEKO TC

TC15 - Experimental Mechanics

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