The effects of a dragonfly’s pterostigmata on the lift and the modal properties of its wings
Date Issued
2014
Date
2014
Author(s)
Chiang, Kuo-Yuan
Abstract
The main object of this thesis is to study the effect of a dragonfly’s pterostigma on its lift force and the dynamical properties of its wings. To measure the lift force, we designed and made a three-dimensional load cell. The deformation of the load cell was measured by laser displacement sensors. To obtain the dynamical properties of a dragonfly’s wing, we used a shaker to excite the wing and a laser displacement sensor to measure the displacement at specified points according to the base excitation method. In this way, a complete set of frequency response functions of the wing were obtained. The natural frequencies and the associated mode shapes were then determined through a curve fitting process. We measured the lift force and wings’ dynamical properties before and after the removal of the pterostigma, and after the adding of some UV glue at the location of the pterostigma, respectively. Moreover, the frequency response function synthesis method was used to calculate the sensitive of the wing’s fundamental frequency to the change of mass at different locations. With the calculated sensitivity, the change of the fundamental frequency due to the removal of petrostigma was estimated and compared with the experimental results. We described in detail the design process of the load cell, experimental procedure to measure the dragonfly’s lift, and method to determine the dynamical properties of the wings; presented experimental results and discussed the effects of a dragonfly’s petrostigma.
Subjects
dragonfly
pterotisgma
lift measurement
modal analysis
sensitivity analysis
Type
thesis
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