Lift & drag analysis of a 3D synthetic dragonfly wing
Thesis DisciplineMechanical Engineering
Degree GrantorUniversity of Canterbury
Degree NameMaster of Engineering
A 3D dragonfly wing is developed by using the Autodesk point cloud methodology, which takes several high definition (HD) pictures of the wing and uploads them into the software which computes all the spatial points and to give a rough matrix of the external structure. The structure is further modified by using Mesh mixer and printed in 3D of Acrylonitrile butadiene styrene (ABS) material. Initially a bending and torsion stiffness test is carried out by cantilevering the wing onto a U shaped frame, where the increasing weights are suspended on the wing tip end to calculate the deflection upon loading at different room temperatures. Keeping the Reynolds and Strouhal numbers constant, a flapping mechanism is de-signed consisting of two smart servo motors connected to the wing root with a fix-tures designed to give the wing four axis degrees of freedom (DOF) maintaining the centre line axis. The servos are programmed by using Arduino Nano board and the whole mechanism is fixed onto two load cells on an apparatus which is connected to a LabView® programme for collecting the data. The data from the load cells is taken and investigated in MatLab® by using Fourier analysis. The maximum deflection of the wing tip as per the literature review is in the range of 3-12 mm depending on the loads acting on the wing during flight. For this thesis the average deflection of the wing tip during the experiment upon applied loading is to be about 3-10 mm. It varies with the forces acting on it and also expected to change for another sample of the model wing which can be produced using flexible PVC which has different properties. These deflection values are used to determine the amount of force acting on the wing tip during the bottom end of the flap cycle. The torsional deflection of the wing during flight was assumed to be 20 degrees. Where as in the torsional stiffness experiment it is more than 10 degrees for the ABS structure. The values obtained during the experiment is lower compared to the value from the previous literature due to the rigidity of the material. It varies with the forces acting on it and also expected to change for another sample of the model wing which can be produced using flexible PVC which has different properties. The flapping experiment is carried out for various flapping and torsional angles us-ing a flapping test rig. The data is studied for the extraction of the forces acting on the wing and is assumed to give more information on the stable and unstable aer-odynamics of the dragonfly wing. It is observed that when the phase difference is changed from 0° to 270° the lift generated value is raised from 0.4N to 0.6N. 𝐶𝐿-max is determined as 0.55 and is maximum when the phase difference between the flapping angle, torsion angle is maintained as 270°. It is reducing for lower phase differences of 90° and 0°. For two consecutive experiments with a 180° phase difference 𝐶𝐿-max is remaining constant at flapping angle of 60°,90° while frequency and torsion angle are maintained constant. The CD is observed to be consistently low and reaching maximum of 0.125 within the experiments. This research values can be used as a source for developing a flapping unmanned aerial vehicle (UAV).