Collaborative Research: Structure and Mechanics of the Bat Wing Membrane in Evolutionary Perspective

所有飞行动物的翅膀都是由外表面的一部分--皮肤、羽毛和/或角质层--组成的，但与内部骨骼、肌肉和神经系统相比，对翅膀结构的这个关键组成部分的研究要少得多。由于皮肤可以构成机翼表面的大部分，了解飞行动物皮肤的机械性质对于了解动物如何飞行以及动物飞行的进化起源和多样性至关重要。蝙蝠与所有其他飞行动物以及人类制造的飞行器的一个不同之处在于，它们的翅膀在飞行过程中会发生巨大的变形和伸展。这项研究计划将重点放在蝙蝠皮的独特结构和功能，以及它如何对蝙蝠的飞行能力做出贡献。这个项目建议了解机翼的蒙皮如何帮助控制3D机翼形状的动态变化，这对蝙蝠的飞行性能是不可或缺的。为了实现这一目标，这个合作项目将整合生物学和工程研究，以深入了解蝙蝠翅膀皮肤的性质，蝙蝠翅膀皮肤是一种非凡而复杂的生物材料。首先，蝙蝠自然飞行的高速视频将被用来记录在正常的翅膀运动中翅膀皮肤是如何伸展和变形的。其次，将对1200多个现存蝙蝠物种中的87个物种的结缔组织和翅膀皮肤下肌肉的结构多样性进行比较分析，选择这些物种代表蝙蝠的多样性和进化关系。第三，将对机翼蒙皮进行独特的机械测试，通过施加力的方式首次模拟蒙皮在飞行中的感受。使用一种利用偏振光的特殊技术，将有可能首次量化整个皮肤样本的微观变形。这一新方法将使我们有可能对作为材料的机翼蒙皮和作为翼型的机翼进行基本了解。最后，来自所有这些研究的数据将被纳入蝙蝠皮结构-性质关系的工程模型中。这些模型不仅将提供对皮肤力学的更深层次的了解，还将对皮肤功能和动力学做出超出实验室测试条件下观察到的预测。工程学越来越多地将设计思想投向生物世界，蝙蝠翅膀结构和材料的研究可以揭示一系列独特的特征，这些特征可以启发新的航空航天材料、翼型设计和其他尖端技术。此外，本文开发的用于高变形机翼蒙皮的理论和建模工具将适用于各种生物和生物医学应用中的组织力学。公众对蝙蝠的迷恋以及蝙蝠优美的形体和动作为交流提供了自然的起点；主要调查人员和他们的学生将在当地公立学校和博物馆进行外联，为许多观众创造基于网络的内容，并参与电影和电视节目。调查人员将特别努力从代表不足的群体中发现、招募和留住本科生和研究生，并让他们成为各级团队的成员。在牙买加金斯敦的NSF-GEMS(工程、数学和科学女孩)项目中将增加一个生物学部分，该项目将纳入牙买加的动物飞行和自然历史。这一改进将扩大该计划的科学范围，为研究生提供外展培训，并让女孩在自己的环境中亲身体验科学。

The wings of all flying animals are composed in part of an outer surface -- the skin, feathers, and/or cuticle -- but this key component of wing structure is much less well studied than the internal skeletal, muscular, and nervous systems. Because skin can make up the majority of the wing surface, understanding the mechanical nature of skin in flying animals is critically important to understanding both how animals fly, and the evolutionary origins and diversification of animal flight. One way in which bats differ from all other flying animals and from the flying vehicles that humans build is that their wings deform and stretch tremendously during flight. This research program will focus on the unique structure and function of bat skin, and how it contributes to the flight capacity of bats. This project proposes to understand how the skin of the wing helps to control the dynamic changes in 3D wing shape that are integral to bat flight performance. To achieve this goal, this collaborative project will integrate biology and engineering research to gain an in-depth understanding of the nature of bat wing skin, a remarkable and complex biological material. First, high-speed videography of natural flight in bats will be used to document how wing skin stretches and deforms during normal wing movements. Second, a comparative analysis of the diversity of structure of connective tissues and muscles underlying wing skin will be undertaken in a group of 87 of the more than 1200 living bat species, selected to represent bat diversity and evolutionary relationships. Third, unique mechanical tests of wing skin will be made by applying forces in a manner that mimics, for the first time, what skin experiences during flight. Using a special technique that employs polarized light, it will be possible to quantify microscopic deformations over entire skin samples for the first time. This new method will make it possible to gain fundamental insights into wing skin as a material and into wings as airfoils. Finally, data from all of these studies will be incorporated into engineering models of structure-property relationships for bat skin. These models will not only provide deeper insights into the mechanics of the skin, but will also make predictions about skin function and dynamics that go beyond what can be observed under laboratory test conditions.Engineering sciences increasingly look to the biological world for design ideas and studies of bat wing architecture and materials can uncover a menu of distinctive traits that can inspire novel aerospace materials, airfoil designs, and other cutting-edge technologies. In addition, theory and modeling tools developed here for highly deforming wing skin will be applicable to tissue mechanics in a variety of biological and biomedical applications. Public fascination with bats and the beauty of bat form and motion provide natural starting points for communication; the principal investigators and their students will conduct outreach at local public schools and museums, create web-based content for many audiences, and participate in film and television programming.The investigators will make special efforts to identify, recruit, and retain undergraduate and graduate students from underrepresented groups, and to involve them as team members at every level. A biology component will be added to the NSF-GEMS (Girls in Engineering, Math & Science) program in Kingston, Jamaica, which will incorporate animal flight and natural history of Jamaica. This enhancement will broaden the range of science in the program, offer outreach training to graduate students, and give girls hands-on experience of science in their own environment.