Surface protection in bio-shields via a functional soft skin layer: Lessons from the turtle shell

Shelef, Yaniv; Bar‐On, Benny

doi:10.1016/j.jmbbm.2017.01.019

Cited by 23 publications

(7 citation statements)

References 53 publications

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“…Load-bearing biocomposites are typically structured as arrays of rigid and predominantly elastic reinforcing elements (e.g., biominerals or crystalline biopolymers), which are connected by a more compliant and energy-dissipating matrix material (e.g., proteins or hemicellulose) through submicron length, compositionally graded, and irregularly-shaped interfacial regions [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. The effective dynamic (viscoelastic) modulus of these interfacial regions provides the biocomposites’ diverse mechanical functions, including adsorbing impacts, detaining cracks, and filtering mechanical signals [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ].…”

Section: Introductionmentioning

confidence: 99%

Assessing the Interfacial Dynamic Modulus of Biological Composites

et al. 2021

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Biological composites (biocomposites) possess ultra-thin, irregular-shaped, energy dissipating interfacial regions that grant them crucial mechanical capabilities. Identifying the dynamic (viscoelastic) modulus of these interfacial regions is considered to be the key toward understanding the underlying structure–function relationships in various load-bearing biological materials including mollusk shells, arthropod cuticles, and plant parts. However, due to the submicron dimensions and the confined locations of these interfacial regions within the biocomposite, assessing their mechanical characteristics directly with experiments is nearly impossible. Here, we employ composite-mechanics modeling, analytical formulations, and numerical simulations to establish a theoretical framework that links the interfacial dynamic modulus of a biocomposite to the extrinsic characteristics of a larger-scale biocomposite segment. Accordingly, we introduce a methodology that enables back-calculating (via simple linear scaling) of the interfacial dynamic modulus of biocomposites from their far-field dynamic mechanical analysis. We demonstrate its usage on zigzag-shaped interfaces that are abundant in biocomposites. Our theoretical framework and methodological approach are applicable to the vast range of biocomposites in natural materials; its essence can be directly employed or generally adapted into analogous composite systems, such as architected nanocomposites, biomedical composites, and bioinspired materials.

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Section: Introductionmentioning

confidence: 99%

Assessing the Interfacial Dynamic Modulus of Biological Composites

et al. 2021

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“…However, the geometries investigated in the archival literature, such as honeycomb and re-entrant, can experience premature local buckling and collapse in the immediate vicinity of the loading, which may amplify the forces on the protected target [1,2]. Some cellular structures that have evolved over millennia and possess unique mechanical characteristics worthy of study, are the trabecular bone [3–5], porcupine quills [6–8], turtle carapaces [9–11] and the beak of the toucan [12–14]. All of these structures are lightweight, have high energy absorption per unit weight and have evolved to resist extreme loadings.…”

Section: Introductionmentioning

confidence: 99%

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

Ghazlan

Ngo

et al. 2020

Jnl of Sandwich Structures & Materials

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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.

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“…Recent work has suggested that the turtle shell might have evolved as an adaption to life underground [4]. In any case, the attractive combinations of different functions have stimulated recent studies of the mechanical performance of structures [6][7][8][9] or components of turtle shells [5,[10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

“…The turtle shell comprises a bi-layered skin that consists of keratin and collagen [10], a sandwiched bone structure including external cortical bones and an internal trabecular bone structure [1,11]. Shelef and Bar-On [10] have used nanoindentation techniques to measure the graded elastic moduli of the red ear turtle skin (Trachemys elegans) [2,14]. Finite element results show that the bi-layered skin structure protects the inner bones from localized impact by reducing the stress concentrations via structural gradients and extensive near surface plasticity.…”

Section: Introductionmentioning

confidence: 99%

Compressive deformation and failure of trabecular structures in a turtle shell

Ampaw

Owoseni

et al. 2019

Acta Biomaterialia

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Turtle shells comprising of cortical and trabecular bones exhibit intriguing mechanical properties. In this work, compression tests were performed using specimens made from the carapace of Kinixys erosa turtle. A combination of imaging techniques and mechanical testing were employed to examine the responses of hierarchical microstructures of turtle shell under compression. Finite element models produced from microCT-scanned microstructures and analytical foam structure models were then used to elucidate local responses of trabecular bones deformed under compression. The results reveal the contributions from micro-strut bending and stress concentrations to the fractural mechanisms of trabecular bone structures. The porous structures of turtle shells could be an excellent prototype for the bioinspired design of deformation-resistant structures.

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Surface protection in bio-shields via a functional soft skin layer: Lessons from the turtle shell

Cited by 23 publications

References 53 publications

Assessing the Interfacial Dynamic Modulus of Biological Composites

Assessing the Interfacial Dynamic Modulus of Biological Composites

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

Compressive deformation and failure of trabecular structures in a turtle shell

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