題目: 以撓性機構彎折翅膀對拍撲機構氣動力及慣性力之影響
研究生: 李祐成
指導教授: 葉思沂 博士
本研究以單自由度之撓性機構為研究主要變因，旨在研究具有固定翼剖面之拍撲機構於內外翼連接處安裝撓性機構後，撓性機構在拍撲過程中被動變形對垂直力所帶來之影響。因此仿照倉鴞(Barn owl)為參考對象，參考其身體尺寸數據與前飛速度計算出翅膀縮放比例及無因次參數，並以此為基礎設計拍撲機構置於均勻流場及穩定來流速度下進行力量量測與拍撲動作分析。
過往用於探討鳥類拍撲時翅膀動作之拍撲機構，常使用連桿、齒輪或線盤等方式主動控制關節自由度模仿鳥類飛行動作。而撓性機構是通過對特定部位進行結構弱化後，使機構受力時所呈現之形變集中在所期望之自由度上。本研究撓性機構本體利用3D列印技術以PETG為材料製造兩種撓性機構(CJ 12, CJ 08)與無撓性之連接塊(CJ NON)，以2 Hz之拍撲頻率，分別於無風(0 m/s)、貼合參考對象史特勞數(3 m/s)和貼合雷諾數(6.6 m/s)的來流下進行實驗。
撓性機構於拍撲過程中，能有效抑制慣性力所造成的拍撲角度不連續情形。拍撲過程中撓性機構依序產生三次形變。力量測結果中，三種連接塊於0 m/s下皆無法產生淨升力。CJ 12與CJ 08於3 m/s來流速度下皆可產生淨升力，CJ NON則只能產生微弱淨升力。在真實鳥類的飛行尺度下，數據顯示CJ 12 下拍轉折點處的第一次形變提供了額外的升力，而第二次變形則是減少了負升力。此外，在上拍轉折點前後，CJ 12 和 CJ 08 都產生出額外的升力，但由於外翼此時的彎折型態並不一致，因此推測此現象可能與內翼周圍的流場有關。這些結果證明，撓性機構使翅膀於拍動時被動形變確實可以增加淨升力的產生。
關鍵字 : 拍撲翼、撓性機構、翼面積變化、等速前飛、力量測

Aerodynamic and Inertia Force Induced by Applying Compliant Joint on Wing-Folding Flapping Mechanism
Student: Yu-Cheng Lee
Advisor: Dr. Szu-I Yeh
International Master Degree Program on Energy Engineering
National Cheng Kung University
SUMMARY
In the past, flapping mechanisms were used to investigate the wing movements of birds. Researchers commonly use connecting rods, gears, or wires to actively control the degree of freedom of joints to imitate the flight movements of birds. In this research, we design a single-degree-of-freedom compliant joint as the main research variable, which can concentrate the deformation to bend the wing as the flapping mechanism perform upstroke. The complaint joint is installed as a link between inner and outer wing with a fixed-wing profile. By changing the design of compliant mechanism, the effect of passive wing deformation on the vertical force can be compared and analyzed.
This study takes Barn owl as reference, calculating the scaling ratio of the wing and dimensionless parameters with reference flight speed. The flapping mechanism is set in a low-speed wind tunnel with uniform flow field and a stable incoming flow to get the data needed for force and motion analysis. In this study, the manufacture of the compliant joint use 3D printing PETG to produce two kinds of compliant joint (CJ 12, CJ 08) and non-flexible connecting blocks (CJ NON). The experiments were conducted under 0 m/s, 3 m/s, and 6.6m/s wind speed with 2Hz flapping frequency to match Reynolds number and Strouhal number separately.
The result shows that the compliant joint can effectively suppress the fluctuation of flapping angle caused by the inertial force impact by deformation. During the flapping process, the compliant joint deforms three times in sequence. In the force measurement results, none of the three designs can generate net lift under 0 m/s wind speed. Both CJ 12 and CJ 08 can generate net lift under 3 m/s wind speed, while CJ NON can only generate weak net lift. Under 3 m/s wind speed, the lift force data show that the first deformation at downstroke reverse point provides additional lift, while the second deformation reduces negative lift. In addition, both CJ 12 and CJ 08 produced extra lift around upstroke reverse point. However, since the deformation angles of CJ 12 and CJ 08 are not consistent at this timing, it is deduced that this phenomenon may be related to the flow field around inner wings.

Keywords: flapping wing, compliant mechanism, wing area change, forward flight, force measurement

[1] A. Wissa et al., “Free Flight Testing and Performance Evaluation of a Passively Morphing Ornithopter,” vol. 7, no. 1, 2015.
[2] D.-B. Thomas, W. Bachmann, H. Wagner, and W. Baumgartner, “Anatomical, Morphometrical and Biomechanical Studies of Barn Owls’ and Pigeons’ Wings,” 2010.
[3] T. Liu, K. Kuykendoll, R. Rhew, and S. Jones, “Avian wing geometry and kinematics,” AIAA Journal, vol. 44, no. 5, pp. 954–963, May 2006, doi: 10.2514/1.16224.
[4] W. Shyy, H. Aono, C. Kang, and H. Liu, An Introduction to Flapping Wing Aerodynamics. Cambridge University Press, 2013. doi: 10.1017/cbo9781139583916.
[5] J. A. Cheney et al., “Bird wings act as a suspension system that rejects gusts: Bird wings act as a suspension system,” Proceedings of the Royal Society B: Biological Sciences, vol. 287, no. 1937, Oct. 2020, doi: 10.1098/rspb.2020.1748.
[6] D. Lentink and M. H. Dickinson, “Rotational accelerations stabilize leading edge vortices on revolving fly wings,” Journal of Experimental Biology, vol. 212, no. 16, pp. 2705–2719, Aug. 2009, doi: 10.1242/jeb.022269.
[7] T. Y. Hubel and C. Tropea, “The importance of leading edge vortices under simplified flapping flight conditions at the size scale of birds (Journal of Experimental Biology 213 (1930-1939)),” Journal of Experimental Biology, vol. 213, no. 14. p. 2548, Jul. 15, 2010. doi: 10.1242/jeb.047886.
[8] R. H. J. Brown, “THE FLIGHT OF BIRDS II. WING FUNCTION IN RELATION TO FLIGHT SPEED.”
[9] B. F. Feshalami, M. H. Djavareshkian, M. Yousefi, A. H. Zaree, and A. A. Mehraban, “Experimental investigation of flapping mechanism of the black-headed gull in forward flight,” Proc Inst Mech Eng G J Aerosp Eng, vol. 233, no. 12, pp. 4333–4349, Sep. 2019, doi: 10.1177/0954410018819292.
[10] M. Huang, “Optimization of flapping wing mechanism of bionic eagle,” Proc Inst Mech Eng G J Aerosp Eng, vol. 233, no. 9, pp. 3260–3272, Jul. 2019, doi: 10.1177/0954410018794339.
[11] 溫登元, “以仿生撲翼機構分析開衩翼尖於拍翅飛行之氣動力效應,” 碩士論文, 航空太空工程學系,國立成功大學, 2020. doi: 10.6844/NCKU202100332.
[12] 陳威瀚, “以多自由度仿生撲翼機構分析雀類腕關節折曲運動於懸停飛行之氣動力效應,” 碩士論文, 航空太空工程學系,國立成功大學, 2020.
[13] D. Billingsley, G. Slipher, J. Grauer, and J. Hubbard, “Testing of a Passively Morphing Ornithopter Wing,” 2009.
[14] B. P. Trease, Y. M. Moon, and S. Kota, “Design of large-displacement compliant joints,” Journal of Mechanical Design, Transactions of the ASME, vol. 127, no. 4, pp. 788–798, Aug. 2005, doi: 10.1115/1.1900149.
[15] L. L. Howell and A. Midha, “A Method for the Design of Compliant Mechanisms With Small-Length Flexural Pivots,” 1994. [Online]. Available: https://mechanicaldesign.asmedigitalcollection.asme.org
[16] P. Bilancia, M. Baggetta, G. Berselli, L. Bruzzone, and P. Fanghella, “Design of a bio-inspired contact-aided compliant wrist,” Robot Comput Integr Manuf, vol. 67, Feb. 2021, doi: 10.1016/j.rcim.2020.102028.
[17] Y. Tummala, A. Wissa, M. Frecker, and J. E. Hubbard, “Design and optimization of a contact-aided compliant mechanism for passive bending,” J Mech Robot, vol. 6, no. 3, Jun. 2014, doi: 10.1115/1.4027702.
[18] Y. Tummala, M. Frecker, A. Wissa, and J. E. Hubbard, “Design of a passively morphing ornithopter wing using a novel compliant spine,” in ASME 2010 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, SMASIS 2010, 2010, vol. 1, pp. 703–713. doi: 10.1115/smasis2010-3637.
[19] P. Nian, B. Song, J. Xuan, W. Zhou, and D. Xue, “Study on flexible flapping wings with three dimensional asymmetric passive deformation in a flapping cycle,” Aerosp Sci Technol, vol. 104, Sep. 2020, doi: 10.1016/j.ast.2020.105944.
[20] Y. Tummala, M. I. Frecker, A. A. Wissa, and J. E. Hubbard, “Design and optimization of a bend-and-sweep compliant mechanism,” Smart Mater Struct, vol. 22, no. 9, Sep. 2013, doi: 10.1088/0964-1726/22/9/094019.
[21] Y. Tummala, M. Frecker, A. Wissa, and J. E. Hubbard, “Design of bend-and-sweep compliant mechanism for passive shape change,” in ASME 2012 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, SMASIS 2012, 2012, vol. 2, pp. 545–553. doi: 10.1115/SMASIS2012-7996.
[22] A. R. Torrado and D. A. Roberson, “Failure Analysis and Anisotropy Evaluation of 3D-Printed Tensile Test Specimens of Different Geometries and Print Raster Patterns,” Journal of Failure Analysis and Prevention, vol. 16, no. 1, pp. 154–164, Feb. 2016, doi: 10.1007/s11668-016-0067-4.
[23] L. E. Vendland, V. v. Volkov-Muzylev, A. N. Demidov, Y. A. Borisov, and Y. A. Gavrilova, “Research of plastics strength properties for 3D printing under normal conditions,” in AIP Conference Proceedings, Dec. 2021, vol. 2412. doi: 10.1063/5.0076504.
[24] S. Guessasma, S. Belhabib, and H. Nouri, “Printability and tensile performance of 3D printed polyethylene terephthalate glycol using fused deposition modelling,” Polymers (Basel), vol. 11, no. 7, Jul. 2019, doi: 10.3390/polym11071220.
[25] V. v. Volkov-Muzylev, L. E. Vendland, Y. A. Borisov, A. N. Demidov, and N. K. Fominykh, “Research of polymers strength properties for 3D printing under normal conditions,” in Journal of Physics: Conference Series, Nov. 2021, vol. 2057, no. 1. doi: 10.1088/1742-6596/2057/1/012107.
[26] D.-B. Thomas, W. Bachmann, H. Wagner, and W. Baumgartner, “Anatomical, Morphometrical and Biomechanical Studies of Barn Owls’ and Pigeons’ Wings,” 2010.
[27] T. Wolf and R. Konrath, “Avian wing geometry and kinematics of a free-flying barn owl in flapping flight,” Exp Fluids, vol. 56, no. 2, pp. 1–18, Feb. 2015, doi: 10.1007/s00348-015-1898-6.
[28] W. M. Loya, K. S. Pregitzer, N. J. Karberg, J. S. King, and C. P. Giardina, “Flying and swimming animals cruise at a Strouhal number tuned for high power efficiency,” Nature, vol. 425, no. 6959, pp. 705–707, Oct. 2003, doi: 10.1038/nature02047.
[29] 周紫濃, “竹纖維拉伸強度之研究,” 碩士論文, 航空太空工程學系,國立成功大學, 2015.
[30] R. Brandon George and R. Brandon, “Design and Analysis of a Flapping Wing Mechanism for Optimization,” 2011. [Online]. Available: https://scholarsarchive.byu.edu/etd/2737