Fig. 5.

Configurations of a plate with a softened region in each quadrant, with Young’s modulus given by (8) with $a=0.5\text{,}p=-50$, increasing c and $\nu =0.5$. In (a) we show the first six neutral curves, illustrating the level of cellular compression ($\xi =-12T(1-{\nu }^2)$) required for the plate to buckle, as a function of softening parameter c. Panels (b)–(g) illustrate the configurations corresponding to each of these curves for $c=100$. Dark blue (resp. red) colouring represents unit downward (resp. upward) buckling. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)