A bio-mimetic cellular structure for mitigating the effects of impulsive loadings – A numerical study

Abstract

Re-entrant and honeycomb cellular structures have shown potential for mitigating the effects of extreme loadings such as those imposed by impacts and near-range air blast. However, these cellular geometries can buckle locally and collapse in the immediate vicinity of the loading, which can limit their effectiveness as a protective element. These deficiencies can be addressed by mimicking alternate, naturally occurring, cellular structures, including that of the porcupine quill, which is studied here. The quill possesses several distinct features that effectively counteract buckling and bending, and minimise weight. This study mimics several structural features of the quill to develop a novel cellular design for counteracting air blast loads such as those associated with detonations of high explosives. The performance of the bio-mimetic structure is benchmarked against traditional hexagonal and re-entrant designs, which have been documented in the archival literature. The quill-inspired structure offers more design freedom than the traditional cellular geometries. By iteratively mimicking several of the structural features of the porcupine quill, an optimal balance between local buckling and collapse can be realised, which minimises the reaction on the target below and maximises energy dissipation.

Uncovering a high-performance bio-mimetic cellular structure from trabecular bone

“…2 ) is constructed with an upper and lower sub-cell, which provides more freedom in design. Comprehensive details on generating the 3D printed bioinspired unit cell using Voronoi diagrams and its demonstrated advantages over traditional hexagonal and re-entrant structures are provided in 15 . The design parameters of the bio-inspired unit cell are summarised as follows: H and W are the height and width of the unit cell, respectively; and are the angles of the upper and lower sub-cell, respectively; and are the lengths of the upper and lower tie, respectively; is the thickness of the unit cell wall; and is the out-of-plane thickness of the unit cell.…”

“…It has long been speculated by researchers that the key to the excellent mechanical properties of bone is hidden in the structural features of its well-organised cellular core, which is composed of organised networks of interconnected trabeculae 13 , 14 . Although trabecular bone is not primarily designed to absorb energy, it has been shown to possess unique structural characteristics that facilitate excellent energy absorption 15 – 17 . Despite that other biological cellular structures such as beetle elytra 7 and porcupine quills 15 , 18 , 19 have been reported to exhibit lightweight, buckling resilience and energy absorption characteristics through mechanical testing, investigations on biomimetic cellular structures for energy absorption applications are generally quite limited.…”

“…Although trabecular bone is not primarily designed to absorb energy, it has been shown to possess unique structural characteristics that facilitate excellent energy absorption 15 – 17 . Despite that other biological cellular structures such as beetle elytra 7 and porcupine quills 15 , 18 , 19 have been reported to exhibit lightweight, buckling resilience and energy absorption characteristics through mechanical testing, investigations on biomimetic cellular structures for energy absorption applications are generally quite limited. Ghazlan et al 20 investigated a cellular structure inspired by trabecular bone under compression and demonstrated its high energy absorption over hexagonal and re-entrant structures.…”

Automated simulation techniques for uncovering high-performance bioinspired cellular structures under blast loads

“…Biomimicry for protective structural engineering is an emerging discipline with significant potential to address this demand. Recent attempts to mimic nature for extreme loading applications include: nacre-like composite panels under blast [6–9] and ballistic impact [10–13]; composite 3D printed conch-like prototype under low velocity impact [14]; fish scale-like panels under ballistic impact [15] and puncture [16–18]; crustacean-like fiber-reinforced composites under low velocity impact [19,20]; bone-like functionally graded foams for ballistic shock mitigation [21]; and lightweight porcupine quill-like cellular solids under blast loading [22], to name a few limited studies. Although bioinspired cellular solids have shown potential advantages as blast resilient protective systems, including lightweight and excellent energy absorption, exhaustive studies to uncover their true capabilities under extreme loads are lacking.…”

“…The main limitation of these structures is that they are built from a limited set of parameters, which reduces the design space considerably. Following these observations, a bioinspired cellular structure based on trabecular bone was developed in our recent work (Figure 1(a) to (c)) [22,34], with the goal of evolving a structure with better performance than current engineered cellular solids. To this end, several design parameters were identified from the complex network of plate-like trabeculae (Figure 1(d)) [35–37], namely the cell angles (α,β,γ) and tie lengths (lut,llt).…”