Gas Damping of Microcantilevers at Low Ambient Pressures

By Rahul Anil Bidkar

Mechanical Engineering, Purdue University, West Lafayette, IN

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This seminar will present a theoretical model for predicting the gas damping of long, rectangular silicon microcantilevers, which are oscillating in an unbounded gaseous medium with the ambient pressures varying over 5 orders of magnitude (1000 > Kn > 0.03). The work is the result of a collaboration with Prof. Alina Alexeenko (AAE). The surrounding gas flow is modeled using a sub—continuum, quasisteady Boltzmann equation with a simplified ellipsoidal statistical Bhatnagar—Gross—Krook (ES—BGK) collision operator. The computational results of the model are used to present a closed—form correlation for gas damping of different microcantilever vibration modes. The correlation is uniformly valid over 5 orders of magnitude of Kn numbers easily spanning the range over the free—molecular, the transition, and the low—pressure slip flow regimes. This presentation, will also compare the predictions of this theoretical model with the detailed experimental data acquired by Ryan Tung through controlled pressure vacuum chamber experiments with silicon microcantilevers vibrating in the fundamental and higher vibration modes. The experiments were recently performed by Ryan Tung in collaboration with Dr. H. Sumali at the Sandia National Laboratories, New Mexico. The agreement between theory and experiments is excellent.


Rahul Bidkar Rahul Bidkar is pursuing a doctoral degree at Purdue University under the guidance of Profs. Arvind Raman and Anil K. Bajaj. He is expected to receive his doctoral degree in December 2008. Before joining Purdue University in August 2003, he obtained a Master of Science in Mechanical Engineering from the University of Missouri—Rolla in August 2003 and a bachelor’s degree in Mechanical Engineering from University of Pune, India in 2001. His research interests are in multi—scale fluid—structure interaction problems with applications to micro— and nanosensors, electronics cooling devices, energy harvesting, and bio fluid mechanics. He has several journal and conference papers on the subject of flow—structure interactions, and dynamics and stability of structures. At Purdue University, he is a recipient of the Magoon award for Teaching Excellence in 2006 and 2008. During this time he has collaborated actively with the groups of Profs. Suresh Garimella (ME) and Alina Alexeenko (AAE). After graduation from Purdue University, he is expected to join the General Electric Company as a Mechanical Engineer at their Global Research Center, New York.

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  • Rahul Anil Bidkar (2008), "Gas Damping of Microcantilevers at Low Ambient Pressures,"

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