Design of Passive, Air-Based Squeeze Film Damping for Kinematic Couplings

Abstract

In precision machine design, kinematic couplings are a common choice for aligning and fixturing parts due to their high repeatability. Their centering ability, along with their high stiffness from hertzian contact, enables kinematic couplings to minimize errors. Although kinematic couplings are applied in dynamic situations such as machining, they are currently designed using only static methods with little regard to vibration-induced error. Machine designers thus do not fully understand how kinematic couplings will behave in situ and do not take advantage of easily applicable damping methods to minimize vibration-induced error. This thesis provides a framework for dynamically modeling kinematic couplings with air-based squeeze film damping. This method of damping takes advantage of the inherent air layer between the top and bottom plates of a kinematic coupling; being so simple to leverage, this work advocates for the inclusion of such damping in every kinematic coupling. This work demonstrates that squeeze film damping can increase a coupling’s damping over 100X, significantly raising dynamic stiffness and reducing vibration-induced error. This work’s design principles will allow for more rigorous and thorough development of kinematic couplings, which is especially necessary for applications where vibration-induced errors must be minimized.