Discontinuous fibrous Bouligand architecture enabling formidable fracture resistance with crack orientation insensitivity

Abstract

<jats:p>Bioinspired architectural design for composites with much higher fracture resistance than that of individual constituent remains a major challenge for engineers and scientists. Inspired by the survival war between the mantis shrimps and abalones, we design a discontinuous fibrous Bouligand (DFB) architecture, a combination of Bouligand and nacreous staggered structures. Systematic bending experiments for 3D-printed single-edge notched specimens with such architecture indicate that total energy dissipations are insensitive to initial crack orientations and show optimized values at critical pitch angles. Fracture mechanics analyses demonstrate that the hybrid toughening mechanisms of crack twisting and crack bridging mode arising from DFB architecture enable excellent fracture resistance with crack orientation insensitivity. The compromise in competition of energy dissipations between crack twisting and crack bridging is identified as the origin of maximum fracture energy at a critical pitch angle. We further illustrate that the optimized fracture energy can be achieved by tuning fracture energy of crack bridging, pitch angles, fiber lengths, and twist angles distribution in DFB composites.</jats:p>

Fish Scales and Their Biomimetic Applications

“…Furthermore, looking into great depths of Bouligand-like structure of a scale from an arapaima scale, numerical simulations provide an evidence in preferring a discontinuity in fibers through the layers of collagen ply to successfully increase fracture resistance and crack insensitivity which is demonstrated in Figure 15 (Wu et al, 2020).…”

“…FIGURE 15 | (A) Discontinuous Bouligand fibers and (B) the numerical result of energy absorption(Wu et al, 2020).…”

Growing Living Composites with Ordered Microstructures and Exceptional Mechanical Properties

“…[ 6 ] Once the fracture occurs, twisting cracks can be developed due to the orientation distribution of mineral fibers, and the propagation of these cracks will make a significant contribution to the internal energy dissipation. [ 38–40 ] As a result, Bouligand‐like type IV structure features a remarkable energy absorption capability (Figure 5E), around 20 times that of type I and 2 times that of type II.…”

“…However, the heterogeneous mineral ply orientations of types III and IV, resembling the Bouigand structure in stomatopod dactyl club, [ 6 ] can efficiently bend, twist, and retard the crack propagation. [ 38–40 ]…”

Adhesion Enhancement of Micropillar Array by Combining the Adhesive Design from Gecko and Tree Frog

“…Borrowing the concepts from lotus leaf and butterfly wing, we created a surface that could be used for acid/base recognition by the regulation of mechanical stress and robust transportation of water droplets. [4] Yu et al [5] It has long been demonstrated the gecko-inspired micropillar array with T-shape tips possesses the best adhesion performance of a given material. The further enhancement of the adhesion performances of T-shape micropillars can offer redundant adhesion to compensate for the inevitable improper contacts.…”