Heidi Reid Mechanical Engineering MS Thesis Defense
- Tuesday, November 5, 2019 at 11:00am
- Jake Jabs Hall, Room 307 - view map
Characterization of a Dynamically Similar Artificial Insect Wing
Micro air vehicles (MAVs) are becoming a useful tool for numerous tasks, such as environmental mapping, search and rescue, and military reconnaissance. As the application areas of MAVs require them to operate at smaller and smaller length scales, traditional propulsion mechanisms (e.g., fixed wings and rotating propellers) are unable to meet these demands. In contrast, flapping wing micro air vehicles (FWMAVs) leverage unsteady aerodynamic mechanisms that enable them to realize flight at sub centimeter-lengths. However, FWMAVs face stark design challenges that preclude autonomous flight, including inefficient energetics and reliable on-board sensing. A comprehensive understanding of flying insect biomechanics may provide valuable design insights to help overcome the challenges experienced by FWMAVs. Insect wings are equipped with biological sensors that provide feedback to control attitude, and wing deformation improves both inertial and aerodynamic power economy. As a result, the insect wing may serve as a design paradigm for the artificial wings employed by FWMAVs.
The objective of the present work is to (1) dynamically characterize real insect wings via experimental modal analysis, and (2) develop dynamically similar artificial wings to be used on FWMAVs or in controlled studies. Artificial insect wing models exist, however to our knowledge none are isospectral and isomodal with respect to their biological counterparts. Isomodality and isospectrality imply they have identical frequency response functions and vibration mode shapes, and thus will deform similarly under realistic flapping conditions. We measured the frequency response function and vibration modes of fresh Hawkmoth Manduca sexta forewings using an electrodynamic shaker and planar scanning vibrometer and estimated the wing’s mass distribution via a cut-and-weigh procedure. Based upon our results, we designed and constructed the artificial wings using fused filament fabrication (FFF) to print a polylactic acid vein structure, where the vein structure is based up the actual size and arrangement present in biological wings. Thin polymer films were manually layered over the vein structure and trimmed to fit the wing boundaries to produce a flat wing structure. We determined that the biological and artificial wings have nearly identical natural frequencies, damping ratios, gain, and shape for the first vibration mode. The second mode exhibited complex modal behavior previously unreported in literature, which likely has significant implications to flapping wing aerodynamics. Our results demonstrate the feasibility of fabricating economical, realistic artificial wings for use in robotic applications moving forward.
- Department of Mechanical & Industrial Engineering