Dynamic calibration of a force and two moments transducer

The complete understanding of a structure's response requires the measurement of angular accelerations and moments as well as linear motions and forces. In order to conduct such tests, it is necessary to have a dynamic calibration of a transducer that can measure both forces and two moments about the orthogonal axis as a function of frequency. A pseudorandom excitation is applied through a taut cable so that no external bending moments are applied to the transducer and the force's line of action is clearly defined. The calibration was performed over a 0 to 800 Hz frequency range under various conditions to establish consistency of transducer performance. This calibration reveals that the electronic part of the piezoelectric crystals' diagonal and cross-axis charge sensitivities and the mechanical part of the structural dynamic characteristics both contribute significantly to the measured transducer frequency response functions. Procedures are described for determing the cross axis charge sensitivity matrix which is required in fare investigations.