GTM presents its latest patented invention: a combination force-acceleration transducer that allows compensating for acceleration forces in dynamic measurements on test rigs.
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Day-to-day industrial processes frequently require the measuring of dynamic forces – unlike metrological traceability, which has yet to advance from its early stages. For the German Calibration Service DKD’s two technical committees “Force and Acceleration” and “Materials Testing Machines”, this was reason enough to start work on a new series of guidelines. The first three sheets of the document series have now been published under the moniker DKD-R 3-10.
Sheet 1 covers "dynamic calibration of force measuring units and testing machines with single-axis loads (fundamentals)". It provides a general classification of dynamic forces and describes various standards, exciters, recorders and electronics. In short, it describes the technical equipment matching the current state of the art.
Sheet 2 deals with "dynamic calibration of force transducers using the sine method". By way of an example, it describes calibration using a shaker system. The calibration identifies a force transducer’s dynamic parameters such as dynamic sensitivity, rigidity and damping based on a mathematical model of the calibration setup.
Identifying these parameters is not yet of any essential significance in everyday industrial operations. But the method is nonetheless an important milestone in the advancement of dynamic guidelines. The sine method is capable of realising dynamic forces well up to around 20 kN – at higher forces, impact methods serve better as they require considerably less energy. Comparing these different calibration methods is only possible by identifying the respective parameters and creating models. Sheet 2 of the guidelines series is thus today already setting the course for translating future research into industrial practice more rapidly.
The guidelines series’s third sheet deals with "dynamic verification of materials testing machines using applied samples". It describes the requirements for measurement testing of a testing machine as part of the static calibration according to DIN EN ISO 7500. The term ‘verification’ was chosen deliberately: strictly speaking, the method does not calibrate because tracing of the applied sample to the national standard is not included. The verification nonetheless offers important findings on the dynamic behaviour of the testing machine and this way backs up the results supplied by the testing machine – and now also allows an accredited calibration service to document this in a calibration certificate.
Also newly published is the guideline DKD-R 3-2 "Calibration of measuring amplifiers for dynamic applications", developed by the working group "Acceleration" of the DKD Technical Committee "Force and Acceleration". Sensors for kinematic or mechanical measurands, such as force, torque or acceleration transducers, usually require a measuring amplifier for data acquisition. In order to make these amplifiers interchangeable, it is necessary to characterize them individually and assure a dynamic traceability. The guideline describes validated methods for characterizing amplifiers of different types and functions for use in dynamic measurements.
All of the DKD guidelines are available free for download on the DKD website at www.PTB.de.
Richtlinie DKD-R 3-2 Kalibrierung von Messverstärkern für dynamische Anwendungen, Ausgabe 04/2019, Revision 0, Physikalisch-Technische Bundesanstalt, Braunschweig und Berlin. doi.org/10.7795/550.20190425
Richtlinie DKD-R 3-10 Blatt 1 Dynamische Kalibrierung von einachsig beanspruchten Kraftmessgeräten und Prüfmaschinen (Grundlagen), Ausgabe 06/2017, Revision 0, Physikalisch-Technische Bundesanstalt, Braunschweig und Berlin. dx.doi.org/10.7795/550.20171212A
Richtlinie DKD-R 3-10 Blatt 2 Dynamische Kalibrierung von Kraftaufnehmern nach dem Sinusverfahren, Ausgabe 05/2019, Revision 0, Physikalisch-Technische Bundesanstalt, Braunschweig und Berlin. doi.org/10.7795/550.20190507A
Richtlinie DKD-R 3-10 Blatt 3 Dynamische Verifizierung von Werkstoffprüfmaschinen mit applizierten Proben, Ausgabe 05/2019, Revision 0, Physikalisch-Technische Bundesanstalt, Braunschweig und Berlin. doi.org/10.7795/550.20190507B