Nonlinear Dynamics of Pneumatic Isolators in Ultra-Precision Manufacturing Machines

Virginia Polytechnic Institute And State University, Blacksburg VA

Investigators

Abstract

Ultra-precision manufacturing (UPM) machines enable the production of micro- and nano-devices that are critical for the advances in the electronics, biomedical, communications and other cutting-edge industries. As a critical step in meeting UPM machine’s stringent precision requirement, they must be isolated from unwanted vibrations stemming from fast moving machines and ground motions. For this purpose, pneumatic (passive) isolators are often preferred over active systems because of their relatively low cost and energy efficiency. Recent studies have demonstrated that the performance of pneumatic isolators can be significantly improved using more sophisticated control approaches. However, those past studies did not account for the well-known inherent complex, and nonlinear, behaviors in pneumatic isolators. The aim of this award is to support fundamental research to understand the nonlinear dynamics of passively-isolated UPM machines and determine how the benefits of nonlinear dynamics can be exploited to improve the performance of pneumatic isolators. The knowledge gained will enable U.S. manufacturing industry to build cheaper, better, and faster UPM machines, advancing national prosperity and impacting efforts to secure the national defense. In a broader context, the findings can also be applied to a broader class of nonlinear mechanical and electromechanical systems. The research work will also help broaden the representation and retention of underrepresented minority (URM) in engineering fields. The research project will be the first to conduct a nonlinear vibration analysis of pneumatic isolators to scientifically reveal whether the benefits of mode coupling observed in linear systems can be extended to nonlinear systems. To this end, a nonlinear system identification via a direct reconciliation of experimental measurements and theoretical modeling will be conducted to detect and quantify the nonlinear stiffness and nonlinear damping of pneumatic isolators. A thorough theoretical analysis will then be carried out to understand the interplay between nonlinear mode coupling, stability, and bifurcation in pneumatic isolated UPM machines. Optimal control theory will be used to determine the optimum design parameters, which will then serve as guidelines for improving the design of pneumatic isolators. Rigorous physical experimentation will be performed to guide and validate the theoretical findings. The outcome of the researched work will lead to new insights on how to exploit nonlinear dynamic phenomena for improving the performance of pneumatic isolators. The PI will continue to focus on the participation from underrepresented groups though connections to the National Society of Black Engineers and other STEM-related activities. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.