In situ determination of the extreme damage resistance behavior in stomatopod dactyl club

Abstract

The structure and mechanical properties of the stomatopod dactyl club have been studied extensively for its extreme impact tolerance, but a systematic in situ investigation on the multiscale mechanical responses under high-speed impact has not been reported. Here the full dynamic deformation and crack evolution process within projectile-impacted dactyl using combined fast 2D X-ray imaging and high-resolution ex situ tomography are revealed. The results show that hydration states can lead to significantly different toughening mechanisms inside dactyl under dynamic loading. A previously unreported 3D interlocking structural design in the impact surface and impact region is reported using nano X-ray tomography. Experimental results and dynamic finite-element modeling suggest this unique structure plays an important role in resisting catastrophic structural damage and hindering crack propagation. This work is a contribution to understanding the key toughening strategies of biological materials and provides valuable information for biomimetic manufacturing of impact-resistant materials in general.

Denoising an X-ray image by exploring the power of its physical symmetry

“…Furthermore, methods like X-ray photon correlation spectroscopy (Shpyrko, 2014) and serial crystallography (Meents et al, 2017;Mehrabi et al, 2021) rely on high-frequency acquisition to collect immense amounts of time-resolved data for structural dynamics extraction or massive molecule screening. Examining the structural and functional changes in dynamic or operando situations is one of the main goals in future synchrotron experiments (Zhang et al, 2020;Dong, Chen et al, 2022), with applications including tracking the residual stress in additive manufacturing processes using X-ray diffraction (Chen et al, 2019;An et al, 2022), following morphological changes of protein and RNA folding using SAXS (Lipfert & Doniach, 2007;Cantara et al, 2017), and examining the loading process of metals under tension using the atomic pair distribution function (PDF) technique (Ketkaew et al, 2018;Bian et al, 2020). The ultra-fast acquisition process can greatly help capture the key sample states.…”

Flexible design in the stomatopod dactyl club

“…The nanostructure of the impact region was shown to be critical in absorbing impact by enabling quasi-plastic deformation at contact points (Amini et al, 2015). Furthermore, fracture mechanics studies showed that this region exhibits an R-curvetype behaviour, thus enhancing the overall fracture tolerance (Dong et al, 2022;Chua et al, 2021). The focus of these preceding studies was mainly the impact region or the impact surface (Grunenfelder et al, 2018;Weaver et al, 2012).…”

“…The stomatopod Odontodactylus scyllarus uses its two dactyl clubs to destroy its prey with bullet-like acceleration (Patek et al, 2004). Given the extreme biomechanics involved in stomatopod hunting, the club material has garnered much interest (Dong et al, 2022;Chua et al, 2023Chua et al, , 2021Amini et al, 2019;Zhang et al, 2016;Weaver et al, 2012;Patek et al, 2004;Currey et al, 1982;Caldwell & Dingle, 1976). More recent studies have focused on the micro-and nanostructure of the dactyl club.…”