Equine hoof wall: Structure, properties, and bioinspired designs
Equine hoof wall: Structure, properties, and bioinspired designs
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DOI：
10.1016/j.actbio.2022.08.028
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发表时间：
2022-09-29
影响因子：
9.7
通讯作者：
Meyers，Marc A.
中科院分区：
文献类型：
--
作者：
Lazarus，Benjamin S.;Luu，Rachel K.;Meyers，Marc A.
马蹄壁具有特殊的抗冲击性和断裂控制，由于其独特的层次结构，包括管状，层状和梯度配置。在这项研究中，蹄壁的结构表征进行揭示以前未知的功能。其中突出的是小管桥，这是成像和量化。蹄壁的水化依赖的粘弹性由简化的Maxwell-Weichert模型描述，具有对应于纳米尺度和介观尺度特征的两个特征弛豫时间。蠕变和松弛试验表明，特定的水化梯度在蹄角蛋白可能会导致减少内部应力所产生的空间刚度的变化。为了更好地理解蹄壁-活体的真实冲击模式，对蹄壁样品进行落塔试验。断口分析表明，蹄壁的增强管状结构占主导地位，在较低的冲击能量，而在较高的冲击能量的管间层状结构占主导地位。在失效后的小管表面上观察到断裂的纤维，这表明小管增强和管间基质的物理交织性质提高了这种天然纤维增强复合材料的韧性。对动态加载中结构-机械性能关系的增强理解导致了增材制造生物启发结构的设计，这些结构在准静态和动态加载中进行了评估。列入梯度结构和lameprazole显着减少持续下降塔测试中的损害，而小管增加了能量吸收的样品在紧凑的张力测试。与蹄壁最相似的样品显示出非常一致的断裂控制性能。显著性声明马蹄壁能够承受大的、重复的动态载荷，被吹捧为抗冲击生物灵感的候选者。然而，我们对这种生物材料及其转化为工程设计的理解是不完整的。在这项工作中，马蹄墙的新功能进行了量化，揭示了这种显着的材料在近自然的加载条件下的分层失效机制。基于对其他角蛋白材料的研究，建立了蹄壁粘弹性响应模型。阐明了水化、应变速率和冲击能对材料响应的作用。最后，制造了基于蹄的介观/微观结构的多材料3D打印设计，并且相对于对照样品表现出有利的能量吸收和断裂控制。
The horse hoof wall exhibits exceptional impact resistance and fracture control due to its unique hierarchical structure which contains tubular, lamellar, and gradient configurations. In this study, structural characterization of the hoof wall was performed revealing features previously unknown. Prominent among them are tubule bridges, which are imaged and quantified. The hydration-dependent viscoelasticity of the hoof wall is described by a simplified Maxwell-Weichert model with two characteristic relaxation times corresponding to nanoscale and mesoscale features. Creep and relaxation tests reveal that the specific hydration gradient in the hoof keratin likely leads to reduced internal stresses that arise from spatial stiffness variations. To better understand realistic impact modes for the hoof wallin-vivo, drop tower tests were executed on hoof wall samples. Fractography revealed that the hoof wall's reinforced tubular structure dominates at lower impact energies, while the intertubular lamellae are dominant at higher impact energies. Broken fibers were observed on the surface of the tubules after failure, suggesting that the physically intertwined nature of the tubule reinforcement and intertubular matrix improves the toughness of this natural fiber reinforced composite. The augmented understanding of the structure-mechanical property relationship in dynamic loading led to the design of additively manufactured bioinspired structures, which were evaluated in quasistatic and dynamic loadings. The inclusion of gradient structures and lamellae significantly reduced the damage sustained in drop tower tests, while tubules increased the energy absorption of samples tested in compact tension. The samples most similar to the hoof wall displayed remarkably consistent fracture control properties.Statement of significanceThe horse hoof wall, capable of withstanding large, repeated, dynamic loads, has been touted as a candidate for impact-resistant bioinspiration. However, our understanding of this biological material and its translation into engineered designs is incomplete. In this work, new features of the horse hoof wall are quantified and the hierarchical failure mechanisms of this remarkable material under near-natural loading conditions are uncovered. A model of the hoof wall's viscoelastic response, based on studies of other keratinous materials, was developed. The role of hydration, strain rate, and impact energy on the material's response were elucidated. Finally, multi-material 3D printed designs based on the hoof's meso/microstructure were fabricated and exhibited advantageous energy absorption and fracture control relative to control samples.