Abstract. Nine european national metrology institutes (NMIs) are collaborating in a new project funded by the european metrology research programme (EMRP) to establish traceable dynamic measurement of the mechanical quantities force, pressure, and torque. The aim of this joint research project (JRP) is to develop appropriate calibration methods, mathematical models, and uncertainty evaluation. The duration of the project is 3 years for a global amount of e3.6 million. It began in September 2011.
During the monitoring of the long term stability of two accelerometers intended for use in the CIPM Key Comparison CCAUV.V-K2, significant deviations of the magnitude results of the single-ended transducer were discovered. These deviations depend on whether the calibration was performed on an armature made of beryllium or of ceramic. Further investigations showed that this effect must be attributed to some not yet readily understood dynamic process between the contact surfaces of the accelerometer and the armature. The relative motion underlying the deviations has a significant systematic influence already at 5 kHz and beyond. Therefore, the effect needs to be considered in some way while comparing results within the key comparison, as some laboratories use beryllium armatures and some use ceramic armatures.The contribution describes the details and outcome of the investigations performed on the topic so far and is intended to trigger the necessary discussion on consequences and solutions.
This paper describes the influence of a constant curvature of the shaker's air bearing guidance on a low frequency primary accelerometer calibration. Based on the mathematical model, three different methods are developed that allow a quantitative evaluation of this disturbing effect and thus the correction of the resulting systematic deviation.All three methods are applied to the example of a primary low frequency accelerometer calibration performed at PTB, and the results are given in comparison to the original uncorrected magnitude of sensitivity results.
During the monitoring of the long term stability of two accelerometers intended for the use in the CIPM Key Comparison CCAUV.V-K2 significant deviations of the magnitude results of the single ended transducer were discovered. These deviations depend on whether the calibration was performed on an armature made of Beryllium or of ceramic. Further investigations exhibited that this effect must be attributed to some not yet readily understood dynamic process between the contact surfaces of accelerometer and armature. The relative motion underlying the deviations have a significant systematic influence already at 5 kHz and beyond. Therefore, the effect needs to be considered in some way while comparing results within the key comparison, as some laboratories are using Beryllium armatures and some are using ceramic armatures. The contribution describes the details and outcome of the investigations performed on the topic so far and is intended to trigger the necessary discussion of consequences and solutions. 10 kHz 20 kHz Kommentar [Unbekannt1]: Auswert ungScanning.ods (xls von M. Brucke) Erstes Diagramm
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