Design of Drawbar Transducers for Measuring Dynamic Forces

ABSTRACT ACCURACY of static calibration for measuring dynamic forces was shown to be a function of the frequency ratio (forcing function frequency/transducer natural frequency). Static calibration used for measuring dynamic draft forces with steel drawbars was shown to have errors less than 1% for frequency ratios less than 0.1. Two analytical methods (lumped mass and wave propagation) for estimating transducer lowest natural frequency were discussed. Accurate reconstruction of dynamic force was shown to depend on the ratio of sampling frequency to the highest frequency present in the dynamic force. Guidelines indicate the dynamic force should be sampled at a frequency six to ten times higher than the highest frequency present in the dynamic force.