Abstract: The present disclosure relates to a method and system for characterization of torque and torsional vibration in rotating bodies. More specifically, the present disclosure describes high-fidelity, high-speed characterization of the rotary motion of a body without the requirement for surface modification. The method and system rely on the inherent properties of the surface of the rotating body to determine the degree to which the rotating body vibrates, twists, or is otherwise translated.

Abstract: A workpiece holder features a grip post having an interior wall structure and an exterior wall structure defining a plurality of expandable sections adapted to engage the wall of a bore formed on a workpiece. The grip post houses a cam arrangement abutting the interior wall structure. A pin arrangement is movably mounted in the grip post and has a tapered head engageable with the cam arrangement. A fluid system is provided for instantaneously imparting longitudinal movement to the pin arrangement whereby the exterior wall structure of the grip post is expanded into gripping relationship with the workpiece bore by the progressive engagement of the tapered head with the cam arrangement.