Recent AE PhD Craig G. Merrett has won the Lockheed Martin Student Paper in Structures Award from the 52nd American Institute of Aeronautics and Astronautics Structures, Structural Dynamics, and Materials Conference (AIAA SDM 2011).
AE PhD Craig G. Merrett
With his advisor, Emeritus Prof. Harry H. Hilton, Merrett presented “Aero-servo-viscoelastic flutter and torsional divergence alleviation for a wing in subsonic, compressible flow.”
Merrett said he studied a rectangular, viscoelastic, cantilever wing, representative of a typical unmanned aerial vehicle (UAV) wing fabricated from high polymer composite materials. The motivation for this problem was to produce a mathematical model of a UAV wing in the subsonic, compressible flow regime and test that model to find the flight speeds when the wing would twist to the point of failure – torsional divergence – and when the wing would oscillate – flutter. The model also included servo controls to examine the effect of those controls on the flight speeds for torsional divergence and flutter.
Developed by another researcher, the aerodynamic model of the subsonic, compressible flow is fairly new. Merrett’s paper was the first application of the aerodynamic model to a viscoelastic wing.
The study confirmed that incompressible aerodynamic models may overestimate the torsional divergence and flutter speeds. New results are that viscoelastic effects of the structure dominate the compressibility correction of the aerodynamics so the change in aerodynamic model is not noticeable, and that the servo controllers offer a slight improvement of the torsional divergence and flutter speeds.
Merrett has finished his PhD studies and recently accepted a position as assistant professor of mechanical and aerospace engineering at Carleton University, Ottawa, Canada.