Investigating the behavior of corrugated composite materials for morphing aircraft applications.
What are morphing wings?
Since the Wright Brothers invented the first airplane in 1903, airplane and flight technology has been constantly evolving. Current flight technology for planes uses a rigid, mechanical flap design to change the lift and drag of the aircraft. However, morphing wings is a futuristic technology that can improve aircraft efficiency by eliminating weight and mechanical systems. The morphing wings technology requires anisotropic materials, high span-wise stiffness and high chord-wise flexibility. And while previous work had identified such materials, this project intended to test the deflection behavior of these materials under flight conditions.
Understanding the needs of a morphing aircraft
My project initially began as a review of current morphing wings technologies and materials. Morphing technology uses flexible skins to reduce drag and weight. Of those flexible skins, sinusoidal geometry proved to be the most effective and was designed by ETH Zurich. I conducted this initial research during my semester abroad in the Laboratory of Composite Materials and Adaptive Structures in ETH Zurich. In my research of this material, I realized that the material hadn't yet been tested using in-flight simulations to determine how the materials would be behave under flight conditions. I then worked with the university to determine how to best model the experiment.
DESIGNing the experiment
Below is a model of the laminate shape that was used for this experiment. The corrugation shape proved to have the highest degree of anisotropy while also maintaining a smoother surface more than other corrugating shapes and angles.
The deflection behavior was analyzed using a composite analysis program and finite element analysis. We also designed the experiment to replicate the length of an average commercial jet and the aerodynamic pressures experienced mid-flight.
We also determined the primary workflow of the experiment. The first step is being able to model the materials property of the specific laminate under the sinusoidal geometry. The second part was using a simplified plate theory to model to deflection. The experiment was conducted using MATLAB and Fortran.
RESULTS and impact
In the experiment, we determined how length impacts the max deflection. The deflection over cord length b based on span length a was 1.25m. The degree of deflection was significant enough that a support structure was needed. We proposed supporting rails to eliminate the larger degrees of deflection. For optimal control of the wing, the top of the corrugated structure should be secured to a rail. This rail may simply be a support or the means of controlling the wing. Recommendations for concept designs and how to proceed with this new knowledge were made.
my role in the project
This research was conducted during my semester abroad in the Laboratory of Composite Materials and Adaptive Structures in ETH Zurich. While this initially began as a simple research project into morphing wings technology, I used my previous aviation experience and proposed testing the materials under current flight conditions. Thus, the idea to investigate aerodynamic deflection started the experiment. My mentor and I worked together to determine how to model the sinusoidal corrugation. A simplified plate model was used and initially performed in MATLAB, which was further conducted in Fortran. I discussed the what the results translated to, made design recommendations and future research considerations. The experiment was eventually published and you can read it here.