Measurement uncertainty analysis of a measurement flexure hinge in a torque standard machine

Abstract

An alternative method to using strain gauges to measure FT (please see Appendix A for a list of definitions) and TM under a static multi-component load by using a hinge flexure (also called measurement flexure or MF) is presented. Its usage in the 5 MN m torque standard machine (TSM) at the Physikalisch-Technische Bundesanstalt (PTB) to detect calibration torque moment shunts is described. The working principle consists of a displacement measurement by an interferometer and the determination of the MF stiffness in a special CSU. Essential measurement uncertainty influences, such as stiffness determination and measurement conditions, are discussed and quantified. The measurement uncertainty budget for this measurement principle is presented. A FE validation for the MF is discussed.