Stockbridge-type damper effectiveness evaluation. I. Comparison between tests on span and on the shaker

This paper deals with an experimental measurement campaign carried out with a modified dynamometric Stockbridge damper clamped to a laboratory test span. The aim is to get the force and the torque exerted between the cable and the damper on a span. This approach allows the mechanical impedance of the damper under real working conditions to be obtained, with the possibility to separate the contribution of the torque and of the force out of the global losses, and to compare these results with those obtained on a shaker where only the vertical motion is imposed, with no rocking. More than 100 experimental test were executed from February 2001 to July 2001, also looking for a metrological validation of the results and for quality assessment of the collected data. In the following, some results are shown, pointing out a comparison between the damper behavior on the span and on dynamic exciter.