CHALLENGES IN PRACTICAL DYNAMIC CALIBRATION

High precision calibration of electromechanical transducers using dynamic loads is a field of rapidly growing demand in industries. But in contrast, the number of validated methods or even written standards is still close to negligible considering the number of measurands concerned. For this reason, the Physikalisch-Technische Bundesanstalt (PTB) has put increasing effort into the field of dynamic measurement of mechanical quantities in the past several years. The dynamic measurands covered so far by this R&D initiative include acceleration, force, pressure and torque. New dynamic calibration facilities have been developed, applying either periodic or shock excitations and using either primary or secondary calibration methods. The working principles of these calibration devices are described subsequently as well as the different approaches for the dynamic characterization of transducers, like step response, impulse response or harmonic response, respectively. From the scientific point of view, the harmonization of different dynamic calibration results is an essential prerequisite towards future standardization work. Despite the different technical realizations, the mathematical procedures and the problems for a dynamic characterization of transducers as well as the dissemination of the dynamic units are generally similar. These challenges are now approached by methods of a model-based calibration, which seem to give very promising results.