In a wide field of application industry needs to measure dynamic forces with accuracies which cannot be met at the present time because an appropriate calibration of force transducers is not yet available.
In a first phase of the project it has been demonstrated that the dynamic calibration of force transducers based upon Newton's second law is, in principle, possible.
It was shown that force transducers of the same (static) class can behave considerably different when exposed to dynamic forces mainly due to their different sensitivities to transverse forces. Transverse movements of the shaker system reduce significantly the accuracy of the calibration. Spring and damping effects between parts screwed together can also influence the accuracy.
A second phase has therefore been started in which the accuracy of the calibration will be improved. This will include:
- the development and application of a new facility for the calibration of force transducers for frequencies up to 1000 Hz and dynamic forces up to 500 N using static preloads of up to 500N. The uncertainty of the calibration facility in the said ranges will be less than 1% in amplitude and less than 1 degree in phase;
- the development of a fast and low-cost calibration method for the dynamic calibration of force transducers in amplitude and phase over a frequency range of 20 - 1000 Hz based upon the comparison of simultaneously loaded force transducers;
- the development of facilities and improvement of interferometrical methods for the calibration of accelerometers in the frequency range of 5 Hz, or less, up to 1600 Hz with an uncertainty of 0.1% in amplitude sensitivity and of 0.2 degrees in the phase.