This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
The objective of the proposed work is to provide fundamental understanding of the nonlinear dynamics of electrostatically actuated doubly-clamped carbon nanotubes,including the effect of slack, and explore in depth the consequences, advantages, and disadvantages of operating these devices in the nonlinear regime. A major obstacle in the development of carbon nanotubes CNTs has been the lack of knowledge of their dynamical behavior. Because of the rich nonlinearities in these devices due to slack, mid-pane stretching, and electrostatic forces, there is ambiguity and unanswered equations of how to realize reliable devices of CNTs. To address these issues, theoretical and experimental works are planned to study the dynamics of CNTs when excited by small and large electric loads composed of a DC electrostatic load uperimposed to an AC harmonic load. Local dynamics issues that are vital for CNTs researchers, such as predicting the nonlinear resonance frequencies of CNTs, softening and hardening behaviors, hysteresis, and primary and secondary excitations will be investigated. Global dynamics issues affecting the stability of CNTs resonators, such as dynamic pull-in, snap through of tubes with slacks, and basin-of-attraction analysis will be conducted. Analytical and numerical methods including perturbation techniques, reduced-order models, and shooting techniques will be utilized. Experimentally, various optical and electrical methods to detect the resonance frequencies, monitor the tubes deflections, and capture the onset of pull-in are proposed to enable comparison and validation of the theoretical work.
The outcome of the proposed research will allow more aggressive utilization of CNTs in useful applications despite their nonlinear behavior since it will present the proper knowledge of how to deal with it. On the other hand, new research avenues can be opened to deliberately utilize the nonlinear dynamics of CNTs to gain unique features and advantages. Exciting possibilities for operating NEMS CNTs in the nonlinear regimes will be revealed, which can lead to discovery of novel sensors and actuators. Further, this research should bridge the gap between experimental measurements and theoretical modeling, which leads to correct calibration of devices and accurate estimation for the physical properties of CNTs. This research will provide excellent training experience for the graduate students from both institutes (SUNY and Cornell). Also, it will train undergraduate minority students through the NSF-funded Binghamton Success Program. Further, a partnership will be established with the NSF-funded Cornell Nanofabrication Facility and the Kavli Institute to create a Nano Wiki that will collect and condense information on nanoscale device fabrication and measurement for broad on-line open access resource to the national and international scientific community. Funds will also allow partnership with the Cornell Institute for Physics Teachers to develop new modules on nanomechanics for dissemination to New York State high school teachers.
