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.
Highlights
Lightweight, high-strength and high-toughness composite materials are continually developed and improved to meet ever-increasing performance needs in construction aerospace and defense sectors (Obradovic et al, 2012; Muneer Ahmed et al, 2021)
Even though the contrast of the acquired 2D images is not ideal, they provide valuable in situ information on the occurrence and evolution of different crack systems, which is of great importance for tracing and analyzing the 3D structure information from 3D ex situ tomography experiments
The four major deflection sites can be spotted in the CT slice image [Fig. 2(i), along the orange dash line]; the first major deflection occurred before the main crack propagated to the impactperiodic interface
Summary
Lightweight, high-strength and high-toughness composite materials are continually developed and improved to meet ever-increasing performance needs in construction aerospace and defense sectors (Obradovic et al, 2012; Muneer Ahmed et al, 2021). Extensive studies have been performed over the past ten years to uncover the structural optimization strategies and toughening mechanisms of the stomatopod dactyl, generating numerous characterization results, and various intrinsic and extrinsic toughening mechanisms have been derived (Weaver et al, 2012; Amini et al, 2014, 2015; Yaraghi et al, 2016; Grunenfelder et al, 2018; Huang et al, 2020; Chua et al, 2021) To date, these studies have already provided innovative inspirations for the manufacture of high-energy absorption and impact-resistant composite materials in industry (Han et al, 2020; Liu et al, 2019; Rivera et al, 2020). DFEM simulations were performed on the reconstructed structure to unveil the mechanical roles of pore canal networks, chitin fiber scaffolds and mineral particles within this critical region of the dactyl club
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