Figure 9.

(a) Initial configuration of the spike leg is modeled by shell elements as a TC, where an AH is left-handed and the TC is right-handed for one turn. (b) Top view of the TC shell model where its coiled-coil structure shows a periodic feature. (c) Zoom-in view of the center showing the connected beam elements for three AH ribbon coils, which simulates their interactions. (d) Deformation of a shell TC under tension up to very large stretching. Three short artificial beam elements are used to eliminate interpenetration between α-helices. The contour colors represent their amount of displacement. The local strain concentration at the tip is zoomed-in. (e) Top view of the TC superimposing the original and deformed configurations. To see this figure in color, go online.