Research

Thermal Runaway in Lithium-ion Batteries

Thermal runaway refers to uncontrollable temperature rise when a temperature threshold has been exceeded. This problem has plagued the Boeing 787 Dreamliner recently. See Battery at Center of Inquiry”, New York Times, January 29, 2013.

Although the Dreamliner is certified to return to the service, the cause for the accidents has yet to be found. We have developed a model that identifies the interactions between two parallel units inside a cell as the cause.

See Thermal runaway due to symmetry breaking in parallel- connected battery cells, International Journal of Energy Research, 2013 Further experiments are planned.

Dynamics of Glass Pipettes Driven by Piezoelectric Impact Actuators

The objective of this research is to understand the dynamics of glass pipettes driven by piezoelectric impact actuators. The glass pipettes are used in intracytoplasmic sperm injection (ICSI). Currently the ICSI procedure is facilitated by filling a part of the glass pipette with mercury for a reason that is not very clear yet. Our ultimate goal is to design a piezo-driven system that does not require mercury for its operation

Microfluidic Channels for Cell Sorting

We use “soft lithography” to make PDMS microfluidic channels. The channels are used to sort sperm cells using fluid flow and the self-propelled motion of the sperm cells

Development of Piezoelectric Self-Propelled Capsule

We try to use the nonlinear interactions between the frictional surfaces to propel a capsule to move in a desired direction.

Friction and Impact in Structural Systems

Friction and impact are two main causes for vibration and noise in structural systems. Our interest is in developing simple models that can used in mechanical designs.

Munoz-Guijosa, J.M., and Feng, Z.C. Stability analysis of a rigid rotor on tilting pad journal bearings. Proceedings of IMechE: Journal of Engineering Tribology, 214 Part J, 243-251, 2000.

Qiu, J. and Feng, Z.C. Impact dynamics of thin plates Computers and Structures 75: 491-506, 2000.

Feng, Z.C. and Zhang, X.-Z.Rubbing phenomena in rotor-stator contact Chaos, Solitons and Fractals, 14, 257-267, 2002

Li, Y. and Feng, Z.C. Bifurcation and chaos in friction-induced vibration, Communications in Nonlinear Science and Numerical Simulation, Vol 9 (6), 571-581, 2004.

Lee, Y. and Feng, Z.C. Dynamic responses to sinusoidal excitations of beams with frictional joints, Communications in Nonlinear Science and Numerical Simulation, Vol 9 (6), 633-647, 2004.

Design and Modeling of MEMS Gyroscopes

We investigate the dynamics and control of MEMS microgyroscopes.

Feng, Z.C. and Gore, K. Frequency responses of vibratory gyroscopes , IEEE Sensors Journal , Vol. 4, 80-84, 2004.

Feng, Z.C., A nonlinear dynamics model of a microelectromechanical vibrating wheel gyroscope Advances in Structural Dynamics (edited by J.M. Ko and Y.L. Xu), Elsevier, Oxford, 283-290, 2000

Haney, J.D., and Feng, Z.C. Achieving close frequency match without incurring instabilities in micro gyrosIMECE 2001/MEMS-23838, Proceedings of 2001 ASME International Mechanical Engineering Congress and Exposition, Nov. 11-16, 2001, New York, NY. 1-5, 2001

Lee, Yongsik, and Feng, Z.C. Feasibility study of parametric excitations of a tuning fork microgyroscope ASME International Mechanical Engineering Congress and Exposition, Nov. 14-19, Anaheim, CA. IMECE2004-59978, 2004

Poreddy, S., Pai, P., and Feng, Z.C. Design compensation for fabrication imperfection of microgyroscopes ASME International Mechanical Engineering Congress and Exposition, Nov. 14-19, Anaheim, CA. IMECE2004-59967, 2004

Fan, M., Feng, Z.C., and Chellaboina, V. Adaptive input estimation methods for high bandwidth microgyros ASME International Mechanical Engineering Congress and Exposition, Nov. 14-19, Anaheim, CA. IMECE2004-61898, 2004

Clark, M., and Feng, Z.C. Dynamic testing of mechanical properties of a substrate using phase-locked loop”, ASME International Mechanical Engineering Congress and Exposition, Nov. 6-11, Orlando, FL, IMECE2005-81392, pp.1-6

Lee, Y. and Feng, Z.C. Design of a parametrically excited tuning fork microgyroscope ASME International Mechanical Engineering Congress and Exposition, Nov. 6-11, Orlando, FL, IMECE2005-81427, pp.1-6