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Figure 4
Morphologies and deformation mechanisms in the damaged dactyl surface. (a) SEM image of the damaged surface of hydrated dactyl club samples, impacted at a speed of 160 m s−1. For convenience, we labeled the surface area with the R1 and R2 regions according to a different radius from the central impacting point. (b)–(e) SEM images of the cross-section of damaged hydrated dactyl club. (b) Low-magnification SEM image showing both plastic and elastic regions formed beneath the impact point. (c) Region featuring large pores owing to the loss of mineral contents. (d) Enlarged view showing a typical plastic zone feature. (e) Enlarged view showing an elastic zone with a textured arrangement. (f) SEM image of a damaged surface of dactyl clubs with a rough surface. (g) The in-plane fibers were pulling out from different layers (highlighted with red lines). (h) Nanocracks in encased mineral of nanofibers and the separation of clustered nanofibrils. (i)–(k) Fiber bridging near the impact point, illustrating the hierarchical fiber bridging: (i) fiber bundle, (j) fiber and (k) nanofiber. |