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The Role of Vanes in the Damping of Bird Feathers

Journal of Bionic Engineering 2023年第4期20卷 1646-1655页

作者： Kai Deng hamed rajabi Alexander Kovalev Clemens F.Schaber Zhendong Dai Stanislav N.Gorb Functional Morphology and Biomechanics Institute of ZoologyKiel University24098KielGermany School of Engineering London South Bank UniversityLondonSE10AAUK Institute of Bioinspired Structure and Surface Engineering Nanjing University of Aeronautics and AstronauticsNanjing210026People’s Republic of China

Bird feathers sustain bending and vibrations during *** unwanted vibrations could potentially cause noise and flight *** could alter the system response,resulting in improving quiet flight,stability,and *** of feathers are known to be indispensable for supporting the aerodynamic function of the *** relationship between the hierarchical structures of vanes and the mechanical properties of the feather has been previously ***,still little is known about their relationship with feathers’damping ***,the role of vanes in feathers’damping properties was *** vibrations of the feathers with vanes and the bare shaft without vanes after step deflections in the plane of the vanes and perpendicular to it were measured using high-speed video *** presence of several main natural vibration modes was observed in the feathers with *** trimming vanes,more vibration modes were observed,the fundamental frequencies increased by 51-70%,and the damping ratio decreased by 38-60%.Therefore,we suggest that vanes largely increase feather damping *** mechanisms based on the morphology of feather vanes are *** aerodynamic damping is connected with the planar vane surface,the structural damping is related to the interlocking between barbules and barbs,and the material damping is caused by the foamy medulla inside barbs.

关键词： Bird Feather Vibrations Damping Bionic

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The frequency of wing damage in a migrating butterfly

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Insect Science 2023年第5期30卷 1507-1517页

作者： Rabiya Korkmaz hamed rajabi Shahab Eshghi Stanislav N.Gorb Thies H.Büscher Department of Functional Morphology and Biomechanics Zoological InstituteKiel UniversityKielGermany Division of Mechanical Engineering and Design School of EngineeringLondon South Bank UniversityLondonUK

The ability to fly is crucial for migratory ***,the accumulation of damage on the wings over time can affect survival,especially for species that travel long *** examined the frequency of irreversible wing damage in the migratory butterfly Vanessa cardui to explore the effect of wing structure on wing damage frequency,as well as the mechanisms that might mitigate wing *** exceptionally high migration rate driven by high precipitation levels in their larval habitats in the winter of 2018–2019 provided us with an excellent opportunity to collect data on the frequency of naturally occurring wing damage associated with long-distance *** images of 135 individuals of *** were collected and analyzed in *** results show that the hindwings experienced a greater frequency of damage than the ***,forewings experienced more severe damage on the lateral margin,whereas hindwings experienced more damage on the trailing *** frequency of wing margin damage was higher in the painted lady butterfly than in the migrating monarch butterfly and in the butterfly Pontia occidentalis following artificially induced wing *** results of this study could be used in future comparative studies of patterns of wing damage in butterflies and other *** studies are needed to clarify whether the strategies for coping with wing damage differ between migratory and nonmigratory species.

关键词： biomechanics cost of migration flight Lepidoptera Vanessa cardui wing structure

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挤压速度对搅拌摩擦反挤压法制备Cu-5%Ti_(2)SnC复合丝材性能的影响

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Transactions of Nonferrous Metals Society of China 2024年第3期34卷 935-951页

作者： Amirhossein JAHANI hamed JAMSHIDI AVAL Mohammad rajabi Roohollah JAMAATI Department of Materials Engineering Babol Noshirvani University of TechnologyShariati AvenueBabol 47148-71167Iran

对粉末冶金法制备的含5%(体积分数)Ti_(2)Sn CMAX相的初始复合材料进行搅拌摩擦反挤压(FSBE)处理,研究FSBE工艺的轴向横移速度对Cu-Ti_(2)Sn C复合线材显微组织、力学性能、电学性能和磨损性能的影响。结果表明,随着挤压速度的增加,显... 详细信息

对粉末冶金法制备的含5%(体积分数)Ti_(2)Sn CMAX相的初始复合材料进行搅拌摩擦反挤压(FSBE)处理,研究FSBE工艺的轴向横移速度对Cu-Ti_(2)Sn C复合线材显微组织、力学性能、电学性能和磨损性能的影响。结果表明,随着挤压速度的增加,显微组织中孪晶增多,Ti_(2)SnC颗粒细化,MAX相和Cu基体之间的界面结合改善。当转速为600r/min,轴向横移速度为25mm/min时,Cu-Ti_(2)SnC复合线材具有最大的硬度、屈服强度和极限抗拉强度,分别为HV 132.7、278.34MPa和485.15MPa,这是其更强的界面结合和更细的MAX相导致的。此外,当转速为600 r/min,轴向横移速度为25 mm/min时,Cu-Ti_(2)SnC复合丝的电导率最高,达到89.21%(IACS),磨损率最低,为0.0015 mg/m,这是其更大的晶粒尺寸、更强的界面结合与更低的密度导致的。

关键词：搅拌摩擦反挤压 Ti_(2)SnC MAX相铜基复合材料电导率

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Effect of extrusion speed on properties of Cu-5 vol.%TiSnC composite wire fabricated by friction stir back extrusion process

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Transactions of Nonferrous Metals Society of China 2023年

作者： Amirhossein JAHANI hamed JAMSHIDI AVAL Mohammad rajabi Roohollah JAMAATI Department of Materials Engineering， Babol Noshirvani University of Technology

The present work investigated the effect of axial traverse speed of friction stir back extrusion (FSBE) process on the microstructure， mechanical， electrical， and wear properties of Cu-Ti2SnC composite wire. The FSBE process was performed on the primary composite made by the powder metallurgy method with 5 vol.% of Ti2SnC MAX phase. The results showed that as the extrusion speed increased， the twins formed in the microstructure increased， the Ti2SnC particles became finer， and the interface of bonding of the MAX phase-Cu matrix improved. The Cu-Ti2SnC composite wire fabricated by the rotational speed of 600 rpm and axial traverse speed of 25 mm/min showed maximum hardness， yield strength， and ultimate tensile strength of 132.7 HV， 278.3， and 485.1 MPa， respectively. This finding was due to its stronger interfacial bonding and finer MAX phase particles. Besides， the larger grain size， better interface bonding， and lower porosity resulted in the highest electrical conductivity of 89.21% IASC and least wear rate of 0.0015 mg/m of Cu-Ti2SnC composite wire fabricated by 600 rpm rotational speed and 25 mm/min axial traverse speed.

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