Duke University Pratt School of Engineering
Mechanical Engineering and Materials Science
My research interest lies in aeroelasticity, the study of interactions between an elastic structure and the surrounding fluid. The fundamental problem is that the elastic deformation of the structure disturbs the surround fluid, which in turn exerts forces on the structure. There are many conditions under which this interaction is unstable, causing growing structural deformations that eventually lead to structural failure.
One particular example is aircraft flutter. All aircraft exhibit flutter after exceeding a high enough air speed. The video below shows a scaled down model of a Boeing 747 undergoing wind tunnel testing.
Aeroelasticity and Flight Dynamics of Folding Wings
My undergraduate research and my master's thesis focus on analyzing the aeroelastic behavior of folding wings, a concept describing a wing that consists of multiple segments that are connected by hinges and can rotate relative to each other. Because of additional actuators and structural accomendations necessary to implement a folding wing design, the overall structure is typically weaker and more susceptible to aeroelastic effects. Furthermore, these morphing wing concepts are typically being explored for micro air vehicles, so elastic deformations may also affect the flight dynamics of these vehicles.
Experimental Testbed for Membrane Flutter
Another one of my projects is to design an experimental testbed for conducting flutter experiments on flexible membranes. This is motivated by one of NASA's concepts for noise reduction on commercial aircraft. A lot of noise is generated off the aircraft during landing when trailing edge flaps are extended because of vortices that are shed from the region between the flaps and the rest of the wing. A flexible membrane can be placed there to create a smoother transition, but flutter may be a concern. The goal of this project is to obtain flutter test data to validate existing theoretical models.
Airfoil with Prescribed Structural Nonlinearities
The third research topic is a spinoff of a nonlinear dynamics class project, in which we built and tested an airfoil with cubic structural nonlinearity in pitch in the wind tunnel to measure flutter speed, flutter frequency, and limit cycle amplitudes. The nonlinearity is created geometrically using a spring that has one end fixed and the other end moving along a specified path. Depending on the shape of the path, either softening or stiffening behavior is possible. The goal of this project is to experimentally demonstrate the proposed geometric method of creating nonlinearities, and also obtain data on nonlinear behavior of the airfoil for both hardening and softening stiffness.