Correcting a Significant and Consistent Error in the Modal Damping Obtained using Transient Vibration Data
COLORADO STATE UNIV FORT COLLINS DEPT OF MECHANICAL ENGINEERING
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This report investigates the experimental vibration technique of impact excitation when used to obtain frequency response functions. It is shown that current practices introduce a consistent error in the derived modal damping estimates. The error can be significant, with levels of damping being wrongly predicted by a factor of three or more. The report identifies the source of the error. It then derives and presents a simple correction to be applied to the observed modal damping estimates. The procedure is demonstrated by experiment.