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Recent Breakthroughs in Nanotechnology
Carbon reinforcement is a staple of composite materials technology, but recent breakthroughs in nanotechnology are opening up new opportunities for this traditional material. In the form of nanotubes, which measure from less than one to a few nanometers (one billionth of a meter) in diameter, carbon displays CCM affiliated faculty member Tsu-Wei Chou, Pierre S. duPont Chair of Engineering and an internationally recognized pioneer in the field, is currently carrying out a comprehensive program of research on the multifunctional properties of carbon nanotubes (CNTs) and their composites. |
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His current research program in this area is carried out in collaboration with a number of colleagues, including Dr. Chunyu Li and Dr. Erik Thostenson, both Associate Scientists in the Department of Mechanical Engineering.
Li's work focuses on analytical multi-scale studies of the static, dynamic, and thermal properties of CNTs and CNT-reinforced polymer- and ceramic-matrix composites. Thostenson is conducting experimental studies on the processing-structure-property relationships of these materials. “The interaction between the analytical and experimental groups has been very fruitful,” says Chou.
According to Chou, Li has pioneered the molecular structural mechanics method as a tool for atomistic analysis. “There are many atomistic tools,” says Chou, “but Dr. Li's is very computationally efficient and very powerful.” The computational efficiency as well as the accuracy and stability of this modeling technique has been validated using existing analytical and experimental data on graphite and carbon nanotubes.
The researchers have also employed this approach to study CNT-based sensors for measuring mass, strain, pressure, and temperature at the nanoscale. “The sensing capability of carbon nanotube-based sensors far exceeds that of current microsensors,” says Li, “and the sensitivities can be enhanced with the use of small carbon nanotubes.”
The team has also studied carbon nanotube-based composites using a combination of the molecular structural mechanics approach and the finite element method, enabling a multiscale analysis. The work has provided valuable information about the behavior of these materials in terms of deformation and stress distributions.
Complementing Li's analytical studies is Thostenson's experimental work. He has developed a novel technique that involves solvent-assisted dispersion followed by melt extrusion and drawing to produce highly aligned CNT composite films. This model nanocomposite system was then utilized as a basis for the team's characterization and modeling research.
“From the model system,” says Thostenson, “we can vary the nanocomposite structure by adjusting the processing conditions. Then we can design experiments to understand the fundamental behavior of the nanotube and examine the multi-scale interaction of nanotubes in a nanotube-based composite.”
“Through this characterization and modeling research,” he continues, “we've developed a modeling approach to account for the structure and size dependence of carbon nanotubes and to predict the resulting composite properties. Ultimately, the establishment of these basic relationships will enable tailoring of these composites at the nano-scale for multifunctional properties.”
Equipment funding from the Air Force has enabled the establishment of core facilities for scaling-up the production of nanocomposites to produce large-scale test specimens as well as facilities to fully characterize their anisotropic thermal and electrical properties.
Chou credits Thostenson with a key ability to collaborate with industry on this breakthrough research. Through an STTR program, the team is addressing the issues involved with tailoring the multi-functional properties of CNT-reinforced composites to achieve desired material properties.
“We first pioneered this approach where carbon nanotubes were used to selectively reinforce the interphase region in traditional carbon-fiber composites,” says Thostenson. “With the collaboration of industrial partners, we have been able to take the concept from model composites, where carbon nanotubes were grown on the surface of individual carbon filaments to examine the interface behavior, to macroscopic woven fabric nanotube/fiber composites.”
The results of the work to date have been published in a broad range of media, including physics, materials science, and applied mechanics journals. The published papers have been among the most highly cited and frequently downloaded works in the field.
Although he has worked in the composites field for close to four decades, Chou is still interested in new challenges and excited about new opportunities. “These new materials have tremendous potential,” he says. “Our challenge is to understand them well enough to enable us to harness that potential.”
OTHER NEWS
| Dr. Wang Honored at 2005 ASC Technical Conference In the 20th Annual Technical Conference, ASC organized a four-session Wang Symposium to honor Dr. Albert S. Wang who has contributed significantly to the field of composites. Dr. Albert Wang is an alumnus of University of Delaware and a long-term friend of CCM. He has had a distinguished career and led the formulation of breakthrough research efforts in the mechanics of composites, particularly those in the area of failure prediction of composites. He has made major contributions to the fundamental understanding of composite material behavior. Among the many recognitions that Dr. Wang has received is the 2000 ASC Outstanding Research Award. |
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2005 Medals of Excellence Awarded From left: |
CCM-Affiliated Grad Student Receives ASC Award The ASC Ph.D. Research Scholarship was awarded to UD Materials Science and Engineering graduate student A. Andres Leal Ayala. Leal is studying the effect of hydrogen bonding on micro-mechanical properties of high-performance organic fibers, working with his advisor, John W. Gillespie, Jr., and CCM Associate Scientist, Joe Deitzel. The award is designated for formally enrolled Ph.D. candidates in engineering and science whose dissertation research is focused on some aspect of composite materials. |
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CCM Faculty Chaired Sessions at ASC
The following CCM faculty chaired sessions in the Wang Symposium during the ASC Technical Conference:
Prof. Jack Vinson - Impact ; Prof Richard Wool - Emerging Materials; Prof Suresh Advani - Processing; Prof. Tsu-Wei Chou - Nanocomposites
CCM Students Receive Awards
Jeffrey Bergman, EG ’07 (Visiting Scholar from Ohio State University), Spirit of McNair Award
Professor Wagner Interviewed by NPR
Listen to the NPR radio interview with Dr. Norman Wagner, Alvin B. and Julia O. Stiles Professor of Chemical Engineering, on shear-thickening fluids for extremity protection using Kevlar(TM). "The Search for a Better Kevlar"
PARTNERING FOR SUCCESS
Published in IA Times, June2005
SPONSOR PROFILE: Amtech Corporation
Proven in Battle
Recognized as one of the fastest growing and most innovative small businesses in the state of Washington, Amtech Corporation, maker of the famous HELMET HARDTOP® for the HMMWV, is a diverse manufacturer of composite-based products and parts.
Full Story (Page 4)
UPCOMING EVENTS
Jack R. Vinson Lecture, Department of Mechanical Engineering
Autonomous Structures: Adding Some Intelligence to Smart Structures
Dr. Daniel J. Inman, Virginia Tech
Oct. 7, 2005; 10:15 a.m., 106 Center for Composite Materials
EMPLOYMENT OPPORTUNITIES
CCM posts positions available for our consortium members and other sponsors on our website at http://www.ccm.udel.edu/Opportunities/jobs.html.
M Cubed Technologies, Inc. - Associate Engineer, Research & Development (Newark, DE)
CCM Position - Limited Term Researcher, Center for Composite Materials (Newark, DE)
CONSORTIUM NEWS
CCM would like to welcome Raytheon Missile Systems, Tucson, AZ, and Degussa Corporation, Piscataway, NJ, to the University-Industry Consortium. AAR Composites, Clearwater, FL, General Dynamics ATP (aka Lunn Industries), Lincoln, NE, W. L. Gore & Associates, Putzbrunn Muenchen, Germany, have recently renewed their memberships and continue to participate in consortium activities.
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