Collaborative Research: Impact Resistant Equine Hoof - Structure, Properties and Bioinspired Designs

角蛋白是一种蛋白质，存在于大多数动物的外层，如毛、指甲、角、蹄、喙和羽毛。角质材料是最坚固的生物材料之一，经过自然界的优化，其功能得到了优化。例如，马蹄在重量轻的同时具有抗冲击性。蹄子可以承受强大的动力，但产生这种特性的根本原因尚不清楚。这项研究将大大提高对蹄子如何吸收能量的理解，并为建立新的抗冲击、生物灵感材料铺平道路。生物灵感的设计包括使用来自自然的想法和使用合成材料来创造新的工程复合结构。抗冲击材料对于广泛的应用是必不可少的，这些应用包括身体保护(防弹背心和头盔)、防御(防爆炸结构)、汽车工业(抗碰撞车辆)、航空航天(飞机鸟击)和空间探索(防止空间碎片)。这一涉及机械工程师、材料科学家和生物学家的跨学科研究和教育计划，包括基于角蛋白的生物系统的实验和计算研究，以及在高速碰撞中具有卓越能量吸收性能的新工程材料的设计和制造。参与的研究生将在学年与本科生配对，在暑期与高中生配对。计划纳入代表人数不足的少数族裔和女学生。研究生将获得在国家实验室接受培训和使用强大仪器的独特经验。本研究的目的是验证以下假设：1.蹄的层次结构有助于吸收能量并抵抗高速撞击；2.多尺度建模可以预测蹄的压缩和冲击行为；3.合成的蹄启发材料将具有优异的抗冲击性能。本研究综合了不同领域(生物力学、材料科学与工程和生物学)的概念和方法。这些方法和途径包括角蛋白材料的最新表征(小角和广角X射线散射、纳米和微型计算机断层扫描、小角中子散射、电子显微镜、纳米到宏观力学测试)、开发新的本构模型，以及基于蹄的特殊性能设计、制造和测试抗冲击生物激励材料。该项目的方法是变革性的，因为它结合了来自自然的想法(加速发现)，利用计算材料科学方法(生成数据)来筛选参数空间并创建结构-财产关系目录，并使用神经网络方法来寻找最佳设计。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Keratin is a protein found on the outer covering of most animals, such as hair, nails, horns, hooves, beaks, and feathers. Keratinous materials are among the most robust biological materials, which have been optimized by nature for their functions. For example, horse hooves are impact resistant while being lightweight. The hooves can withstand powerful and dynamic forces, but the fundamental reasons that give rise to this property are not known. This research will significantly advance understanding of how hooves absorb energy and pave the way to build new impact-resistant, bioinspired materials. Designs by bioinspiration involve using ideas from nature and employing synthetic materials to create new engineering composite structures. Impact resistant materials are essential for a wide range of applications, which include body protection (body armor vests and helmets), defense (blast resistant structures), automotive industry (crash-resistant vehicles), aerospace (aircraft bird strikes), and space exploration (protection against space debris). This transdisciplinary research and educational program involving mechanical engineers, materials scientists, and biologists, includes the experimental and computational studies of keratin-based biological systems and designs and fabrication of new engineering materials with a superb energy absorption performance during high-speed impacts. The participating graduate students will be paired with undergraduate researchers during the academic year and high school students during the summer. Inclusion of underrepresented minority and women students is planned. The graduate students will have the unique experience of getting trained and using powerful instruments at national laboratories. The objectives of this research project are to test the following hypotheses:1. The hierarchical structure of hooves assists in energy absorption and resists high-speed impacts, 2. Multiscale modeling can predict the compression and impact behaviors of hooves,3. Synthetic hoof-inspired materials will have outstanding impact resistant properties.This research integrates concepts and methods from diverse fields (biomechanics, materials science and engineering, and biology). The methods and approaches include the state-of-the-art characterization of keratin-based materials (small and wide angle X-ray scattering, nano-and micro-computed tomography, small angle neutron scattering, electron microscopy, nano- to macroscale mechanical testing), development of new constitutive models, and designing, building and testing of impact resistant bioinspired materials based on the exceptional properties of hooves. This project's approach is transformative as it incorporates ideas from nature (accelerates discovery), utilizes a computational materials science approach (generates data) to screen parameter space and create a catalog of structure-property relations, and employs neural network approach to find optimal designs.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.