In an attempt to realize a flapping wing micro-air vehicle with morphing wings, we report on improvements to our previousfoldable artificial hind wing.Multiple hinges, which were implemented to mimic the bending zone ...In an attempt to realize a flapping wing micro-air vehicle with morphing wings, we report on improvements to our previousfoldable artificial hind wing.Multiple hinges, which were implemented to mimic the bending zone of a beetle hind wing, weremade of small composite hinge plates and tiny aluminum rivets.The buck-tails of rivets were flared after the hinge plates wereassembled with the rivets so that the folding/unfolding motions could be completed in less time, and the straight shape of theartificial hind wing could be maintained after fabrication.Folding and unfolding actions were triggered by electrically-activatedShape Memory Alloy (SMA) wires.For wing folding, the actuation characteristics of the SMA wire actuator were modifiedthrough heat treatment.Through a series of flapping tests, we confirmed that the artificial wings did not fold back and arbitrarilyfluctuate during the flapping motion.展开更多
In this study, we present a complete structural analysis ofAllomyrina dichotoma beetle＇s hind wings by investigating their static and dynamic characteristics. The wing was subjected to the static loading to determine...In this study, we present a complete structural analysis ofAllomyrina dichotoma beetle＇s hind wings by investigating their static and dynamic characteristics. The wing was subjected to the static loading to determine its overall flexural stiffness. Dy- namic characteristics such as natural frequency, mode shape, and damping ratio of vibration modes in the operating frequency range were determined using a Bruel ＆ Kjaer fast Fourier transform analyzer along with a laser sensor. The static and dynamic characteristics of natural Allomyrina dichotoma beetle＇s hind wings were compared to those of a fabricated artificial wing. The results indicate that natural frequencies of the natural wing were significantly correlated to the wing surface area density that was defined as the wing mass divided by the hind wing surface area. Moreover, the bending behaviors of the natural wing and artificial wing were similar to that of a cantilever beam. Furthermore, the flexural stiffness of the artificial wing was a little higher than that of the natural one whereas the natural frequency of the natural wing was close to that of the artificial wing. These results provide important information for the biomimetic design of insect-scale artificial wings, with which highly ma- neuverable and efficient micro air vehicles can be designed.展开更多
This study aims to examine the following three hypotheses on the impact of global warming on the populations of the water strider, Aquarius paludum in the Kochi-Nankoku area (33。30'N) of Kochi prefecture, Japan t...This study aims to examine the following three hypotheses on the impact of global warming on the populations of the water strider, Aquarius paludum in the Kochi-Nankoku area (33。30'N) of Kochi prefecture, Japan through the recent data collected in 2009-2011. 1) Has the generation number increased? 2) Has aestivation appeared in adults? 3) Have overwintering adults stopped dispersing between the water surface and overwintering lands-sites far away from water and, instead, overwintered on/near the shore? Sampling data showed that the number of generations may have increased from three (1989-2002 strains) and four (2004-2008) to five (2009-2011) per year in Kochi (33。N). The ratio of adults having well developed flight muscles decreased from 45% in 1995 to 24% - 28% in 2009-2011 inoverwintering adults collected from the field in fall likely as a result of histolysis. “Mosaic-typed” wing morph group with long fore-wings and short hind-wings newly appeared in 2009-2011 in the Kochi-Nankoku overwintering populations. The mosaic-typed wings group cannot fly and the black and long fore wings might function as absorbing apparatus of sun-lights in the daytime of winter. Some overwintering adults seem to stop migrating between water bodies and overwintering sites on land far from the water bodies and overwinter, instead, near the shore. The use of Aquarius paludum as a biological indicator would be possible in the future, because this species can respond and change their reproductive and dispersal characteristics to the global change.展开更多
Detailed 3-Dimensional （3D） wing kinematics was experimentally presented in free flight of a beetle, Trypoxylus dichotomus, which has a pair of elytra （forewings） and flexible hind wings. The kinematic parameters ...Detailed 3-Dimensional （3D） wing kinematics was experimentally presented in free flight of a beetle, Trypoxylus dichotomus, which has a pair of elytra （forewings） and flexible hind wings. The kinematic parameters such as the wing tip trajectory, angle of attack and camber deformation were obtained from a 3D reconstruction technique that involves the use of two synchronized high-speed cameras to digitize various points marked on the wings. Our data showed outstanding characteristics of deformation and flexibility of the beetle＇s hind wing compared with other measured insects, especially in the chordwise and spanwise directions during flapping motion. The hind wing produced 16% maximum positive camber deformation during the downstroke. It also experienced twisted shape showing large variation of the angle of attack from the root to the tip during the upstroke.展开更多
In this work, we develop an artificial foldable wing that mimics the hind wing of a beetle （Allomyrina dichotoma）. In real flight, the beetle unfolds forewings and hind wings, and maintains the unfolded configuratio...In this work, we develop an artificial foldable wing that mimics the hind wing of a beetle （Allomyrina dichotoma）. In real flight, the beetle unfolds forewings and hind wings, and maintains the unfolded configuration unless it is exhausted. The artificial wing has to be able to maintain a fully unfolded configuration while flapping at a desirable flapping frequency. The artificial foldable hind wing developed in this work is based on two four-bar linkages which adapt the behaviors of the beetle＇s hind wing. The four-bar-linkages are designed to mimic rotational motion of the wing base and the vein folding/unfolding motion of the beetle＇s hind wing. The behavior of the artificial wings, which are installed in a flapping-wing system, is observed using a high-speed camera. The observation shows that the wing could maintain a fully unfolded configuration during flapping motion. A series of thrust measurements are also conducted to estimate the force generated by the flapping-wing system with foldable artificial wings. Although the artificial foldable wings give added burden to the flapping-wing system because of its weight, the thrust measurement results show that the flapping-wing system could still generate reasonable thrust.展开更多
基金supported by the Korea Science and Engineering Foundation Grant(National Research Laboratory Program,R0A-2007-000-200012-0)the Korea Research Foundation(KRF-006-005-J03301)partially supported by the 2009 KU Brain Pool of Konkuk University
文摘In an attempt to realize a flapping wing micro-air vehicle with morphing wings, we report on improvements to our previousfoldable artificial hind wing.Multiple hinges, which were implemented to mimic the bending zone of a beetle hind wing, weremade of small composite hinge plates and tiny aluminum rivets.The buck-tails of rivets were flared after the hinge plates wereassembled with the rivets so that the folding/unfolding motions could be completed in less time, and the straight shape of theartificial hind wing could be maintained after fabrication.Folding and unfolding actions were triggered by electrically-activatedShape Memory Alloy (SMA) wires.For wing folding, the actuation characteristics of the SMA wire actuator were modifiedthrough heat treatment.Through a series of flapping tests, we confirmed that the artificial wings did not fold back and arbitrarilyfluctuate during the flapping motion.
文摘In this study, we present a complete structural analysis ofAllomyrina dichotoma beetle＇s hind wings by investigating their static and dynamic characteristics. The wing was subjected to the static loading to determine its overall flexural stiffness. Dy- namic characteristics such as natural frequency, mode shape, and damping ratio of vibration modes in the operating frequency range were determined using a Bruel ＆ Kjaer fast Fourier transform analyzer along with a laser sensor. The static and dynamic characteristics of natural Allomyrina dichotoma beetle＇s hind wings were compared to those of a fabricated artificial wing. The results indicate that natural frequencies of the natural wing were significantly correlated to the wing surface area density that was defined as the wing mass divided by the hind wing surface area. Moreover, the bending behaviors of the natural wing and artificial wing were similar to that of a cantilever beam. Furthermore, the flexural stiffness of the artificial wing was a little higher than that of the natural one whereas the natural frequency of the natural wing was close to that of the artificial wing. These results provide important information for the biomimetic design of insect-scale artificial wings, with which highly ma- neuverable and efficient micro air vehicles can be designed.
文摘This study aims to examine the following three hypotheses on the impact of global warming on the populations of the water strider, Aquarius paludum in the Kochi-Nankoku area (33。30'N) of Kochi prefecture, Japan through the recent data collected in 2009-2011. 1) Has the generation number increased? 2) Has aestivation appeared in adults? 3) Have overwintering adults stopped dispersing between the water surface and overwintering lands-sites far away from water and, instead, overwintered on/near the shore? Sampling data showed that the number of generations may have increased from three (1989-2002 strains) and four (2004-2008) to five (2009-2011) per year in Kochi (33。N). The ratio of adults having well developed flight muscles decreased from 45% in 1995 to 24% - 28% in 2009-2011 inoverwintering adults collected from the field in fall likely as a result of histolysis. “Mosaic-typed” wing morph group with long fore-wings and short hind-wings newly appeared in 2009-2011 in the Kochi-Nankoku overwintering populations. The mosaic-typed wings group cannot fly and the black and long fore wings might function as absorbing apparatus of sun-lights in the daytime of winter. Some overwintering adults seem to stop migrating between water bodies and overwintering sites on land far from the water bodies and overwinter, instead, near the shore. The use of Aquarius paludum as a biological indicator would be possible in the future, because this species can respond and change their reproductive and dispersal characteristics to the global change.
文摘Detailed 3-Dimensional （3D） wing kinematics was experimentally presented in free flight of a beetle, Trypoxylus dichotomus, which has a pair of elytra （forewings） and flexible hind wings. The kinematic parameters such as the wing tip trajectory, angle of attack and camber deformation were obtained from a 3D reconstruction technique that involves the use of two synchronized high-speed cameras to digitize various points marked on the wings. Our data showed outstanding characteristics of deformation and flexibility of the beetle＇s hind wing compared with other measured insects, especially in the chordwise and spanwise directions during flapping motion. The hind wing produced 16% maximum positive camber deformation during the downstroke. It also experienced twisted shape showing large variation of the angle of attack from the root to the tip during the upstroke.
文摘In this work, we develop an artificial foldable wing that mimics the hind wing of a beetle （Allomyrina dichotoma）. In real flight, the beetle unfolds forewings and hind wings, and maintains the unfolded configuration unless it is exhausted. The artificial wing has to be able to maintain a fully unfolded configuration while flapping at a desirable flapping frequency. The artificial foldable hind wing developed in this work is based on two four-bar linkages which adapt the behaviors of the beetle＇s hind wing. The four-bar-linkages are designed to mimic rotational motion of the wing base and the vein folding/unfolding motion of the beetle＇s hind wing. The behavior of the artificial wings, which are installed in a flapping-wing system, is observed using a high-speed camera. The observation shows that the wing could maintain a fully unfolded configuration during flapping motion. A series of thrust measurements are also conducted to estimate the force generated by the flapping-wing system with foldable artificial wings. Although the artificial foldable wings give added burden to the flapping-wing system because of its weight, the thrust measurement results show that the flapping-wing system could still generate reasonable thrust.
