This report describes investigations carried out to determine test cycle sensitivity coefficients for the Rockwell HRA hardness scale. Sensitivity coefficients were determined for the preliminary-force, total-force and recovery-force dwell times. The work was carried out in 2017 at the National Institute of Standards and Technology (NIST) in Gaithersburg, USA.
The traceability of the torque quantity finds a gap when there is a regime with torque variation rates. The traditional calibration methods define the references to be on the static regime, with null torque rates. This paper presents a method for providing torque traceability to rotating sensors under high torque variation rates. The principle of applying acceleration pulses to rotating shafts, with mounted reference discs with known mass moments of inertia thereon, is presented herein, followed by a description of sequential proceedings for obtaining an analysis in the time domain. The development of the uncertainty budget is also discussed. Demonstrative experimental data is used in order to ratify the principle and to maintain a qualitative approach to the theoretical description of these methods. The research gives a very good idea of the necessary different future approaches to guarantee traceability for mechanical quantities.
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