Gary D. Seidel, assistant professor of aerospace engineering in the College of Engineering at Virginia Tech, has received a Ralph E. Powe Junior Faculty Enhancement Award to support development of a carbon nanotube-enhanced composite for structural health monitoring sensors to improve the resiliency of huge wind turbine blades.
Powe awards provide seed money for research at Oak Ridge Associated Universities (ORAU) member institutions. These awards are intended to enrich the research and professional growth of young faculty and result in new funding opportunities. Seidel's research also overlaps with several Oak Ridge National Laboratory (ORNL) initiatives, including addressing global warming through alternative energy, advancing active materials, and advancing multiscale characterization and modeling.
Wind turbine blades enjoy a steady wind but can be damaged by gust-induced vibrations. Seidel proposes to create tiny sensor patches that can be selectively placed in key locations where it is anticipated that damage will start. The patches are made of the same base material as the blade but sprinkled with carbon nanotubes, resulting in a nanocomposite sensor which adds negligible weight to the structure.
The submicroscopic carbon nanotubes can be highly conductive, like invisible, extremely lightweight, electrical wires. Placing the highly conducting carbon nanotubes inside a polymer material makes the resulting nanocomposite patch's conductivity sensitive to deformation. As the material is deformed by a stress on the blade, the nanotubes shift, move closer together, and their conductivity jumps – one mechanism behind the phenomenon known as a "piezoresistive response." The change in the nanocomposite conductivity sends a signal to the wind turbine control center, allowing the operator to then know which blade is stressed and should be turned off to prevent further damage to that turbine.
Seidel's focus is on assessing the sensing capabilities of the nanocomposite and building multiscale models for use in structural health monitoring software algorithms. His preliminary models have demonstrated that he can create nanocomposites that respond to stresses with conductivity changes. He will begin actual sensor development this summer.
"Based on what we have learned about the mechanism behind the piezoresistive response of our nanocomposites, we will create the necessary tools for nanocomposite sensor development and tailoring for the wind turbine blade application," Seidel said. "And we will also know a great deal more about the mechanism and potential of nanocomposites for structural health monitoring."
He said that the Nanoscale Characterization and Fabrication Laboratory, part of Virginia Tech's Institute for Critical Technology and Applied Science, and the College of Engineering's Aerospace Structures and Materials Laboratory, make it possible for him to conduct the basic multiscale characterization research, to construct a 3-D image of the nanotubes network within the matrix, and to identify key features such as network morphology, nanotube orientation, and nanotube waviness, needed to develop accurate multiscale models of nanocomposite piezoresistive response.
Seidel joined Virginia Tech in August of 2008. He has been working in the area of multiscale modeling of the mechanical and non-mechanical properties of polymer nanocomposites for the past six years through projects sponsored by the National Science Foundation, Sandia National Laboratories, NASA, and the Air Force Office of Scientific Research. His research focus is on developing integrated computational mechanics models to predict material properties and structural response of nanocomposites across length scales ranging from a few nanometers, through the micron scale, and up to the structural scale. He received Ph.D.in aerospace engineering from Texas A&M University in 2007.
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