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Abstract：
Birds, bats and insects have evolved unique wing structures to achieve a wide range of flight capabilities. Insects have relatively stiff and passive wings, birds have a complex and hierarchical feathered structure and bats have an articulated skeletal system integrated with a highly stretchable skin. The compliant skin of the wing distinguishes bats from all other flying animals and contributes to bats\' remarkable, highly manoeuvrable flight performance and high energetic efficiency. The structural and functional complexity of the bat wing skin is one of the least understood although important elements of the bat flight anatomy. The wing skin has two unusual features: a discrete array of very soft elastin fibres and a discrete array of skeletal muscle fibres. The latter is intriguing because skeletal muscle is typically attached to bone, so the arrangement of intramembranous muscle in soft skin raises questions about its role in flight. In this paper, we develop a multi-scale chemo-mechanical constitutive model for bat wing skin. The chemo-mechanical model links cross-bridge cycling to a structure-based continuum model that describes the active viscoelastic behaviour of the soft anisotropic skin tissue. Continuum models at the tissue length-scale are valuable as they are easily implemented in commercial finite element codes to solve problems involving complex geometries, loading and boundary conditions. The constitutive model presented in this paper will be used in detailed finite element simulations to improve our understanding of the mechanics of bat flight in the context of wing kinematics and aerodynamic performance.
摘要：
鸟,蝙蝠和昆虫已经进化出独特的机翼结构，以实现广泛的飞行能力。昆虫有相对僵硬和被动的翅膀，鸟类具有复杂的分级羽毛结构，蝙蝠具有关节骨骼系统，并具有高度可拉伸的皮肤。翅膀的柔顺皮肤将蝙蝠与所有其他飞行动物区分开来，并有助于蝙蝠的显着，高度机动的飞行性能和高能量效率。蝙蝠翼皮肤的结构和功能复杂性是蝙蝠飞行解剖结构中最不了解的重要元素之一。机翼皮肤具有两个不寻常的特征：非常柔软的弹性蛋白纤维的离散阵列和骨骼肌纤维的离散阵列。后者很有趣，因为骨骼肌通常附着在骨骼上，因此，膜内肌肉在柔软皮肤中的排列引起了人们对其在飞行中的作用的质疑。在本文中,我们建立了蝙蝠翼皮肤的多尺度化学力学本构模型。化学力学模型将跨桥循环与基于结构的连续体模型联系起来，该模型描述了软各向异性皮肤组织的主动粘弹性行为。组织长度尺度的连续体模型很有价值，因为它们很容易在商业有限元代码中实现，以解决涉及复杂几何形状的问题。载荷和边界条件。本文提出的本构模型将用于详细的有限元仿真中，以提高我们对机翼运动学和空气动力学性能的蝙蝠飞行力学的理解。
