蝙蝠生活在洞窟、森林等複雜環境，並擁有多樣化的覓食習性，因此飛行能力對其至關重要，蝙蝠的前肢具有多個關節，能為飛行時提供相當多的自由度，使飛行具有機動性和穩定性。此外，翼膜的彈性纖維不僅能提供保護作用，還有助於在多自由度運動中保持翼膜的張力，使其能夠保持其形狀。
本實驗將研究蝙蝠懸停飛行條件下，改變翼膜彈性對氣動力效應的影響，將設計一個具有兩個自由度的機構，分別為拍撲動作及收折動作，由於蝙蝠翼變形複雜，因此將收折動作簡化，僅保留肘部與腕部變化較大的部分，並以四連桿機構控制。翼膜製造則使用Polydimethylsiloxane(PDMS)作為材料，厚度為0.2 mm，以A:B為10:1、30:1、50:1的比例做為實驗參數，較高的比例使楊氏係數降低並具有高延伸性，高延展性在拍撲時產生較大的彎度(Camber)，形成更強的翼前緣渦流，進而提升垂直力，在水平力方面，楊氏係數降低導致氣動彈性數(Aeroelastic number)隨之下降，增加水平力的產生，然而過低的氣動彈性數將導致水平力下降。
這項研究對蝙蝠的複雜飛行運動進行簡化，並以簡單的方式製作易於調整機械性質的薄膜，再提供了垂直方向及水平方向的氣動力量測以及流場觀測的結果，希望在未來拍撲型無人機在懸停條件下的穩定性提供參考。

Bats inhabit complex environments such as caves and forests and have diverse foraging behaviors, making flight ability crucial for their survival. The multiple joints in a bat's forelimbs provide them with a significant degree of freedom during flight, enabling both maneuverability and stability. Additionally, the elastic fibers in their wing membranes not only offer protection but also help maintain tension in the membrane during multi-degree of freedom movements, allowing them to retain their shape.
The objective of this experiment is to study the influence of varying wing membrane elasticity on aerodynamic effects during hovering flight conditions in bats. To achieve this, we designed a two degree of freedom mechanism to control flapping and folding motions. Given the intricate nature of bat wing membrane deformation, this study focuses on the regions with more significant variations in the elbow and wrist during the folding motion, utilizing a four-bar linkage mechanism to control the wing membrane folding.
In terms of wing membrane fabrication, we used Polydimethylsiloxane (PDMS) as the material and the thickness is 0.2 mm. Different experimental parameters, namely A:B ratios of 10:1, 30:1, and 50:1, were adjusted to modify the wing membrane's elastic properties. Higher A:B ratios lower the Young's modulus and give the wing membrane greater extensibility. This results in larger camber during flapping, forming stronger leading edge vortex, and consequently increasing the vertical lift force. However, the decrease in Young's modulus also leads to a reduction in the Aeroelastic number. Decreasing the Aeroelastic number improves the horizontal forces, but if the Aeroelastic number becomes too low, the horizontal force will decrease.
This study simplifies the complex flight movements of bats and provides measurements of aerodynamic forces and flow field observations in the vertical and horizontal directions by manufacturing membrane with easily adjustable mechanical properties. The results of this research are expected to provide valuable insights for the design of hovering-capable unmanned aerial vehicles in the future, as well as hold considerable value for the development of bio-inspired aircraft.

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