Fig. 2: A beaded shell is compressed between two plates.
From: Beaded metamaterials
a Photographs of the experiment. Constant tension (T0) is applied to the thread ends as the indenter moves a distance δ. Shaded regions show the maximum and minimum force over all trials, and solid black lines show a moving average. Scale bar, 10 mm. b and c The force response (F) for identical shells threaded with different materials (0.25 mm diameter nitinol and 0.50 mm diameter nylon, respectively) as a function of δ, cycled three times across a range of T0. Loading and unloading paths are marked with black and white arrows, respectively. d Maximum load as a function of tension for shells beaded with nitinol (blue) and nylon (green) thread. Maximum forces that occur in a superjammed regime are outlined. e Illustration of a 5-bead building block that comprises the model structure. Gray lines indicate bead hole orientation. f and g Tracking selected beads' motion over a single cycle across a range of T0. f In-plane dilation of the bottom layer of beads measured by the length of exposed thread (Δϵ) as a function of δ. g Altitudinal angles θ1 and θ2 as a function of δ. h Projection of F as in-plane tension between two pink beads shown as a function of Δϵ. A 3-part piecewise linear fit is shaded behind each trial. The return path is not shown in (f–h). Source data is available in Supplementary Data 1.
