Effect of Number of Measurement Locations in the Implementation of Iterative Wavenumber Fitting for Viscoelastically Damped Structures

The work presented here is an experimentally-based parametric study of a layered viscoelastically-damped system containing intermediate structural fasteners. The effect of fastener preload, fastener location and the number of fasteners on the loss factor are examined. The loss factor is found to change by as much as 22% with change in some of these parameters. Two different approaches are used to measure loss factor. The first method uses the internal algorithm from a signal analyzer. The second method is an iterative algorithm that estimates the complex wavenumber, which is then used to find the damping loss factor. An advantage of the latter technique is the ability to measure loss factor over a range of frequencies. This research also investigates the effect of the number of measurement positions on the accuracy of loss factor. It is shown that the accuracy has a strong dependence on the number of measurement locations, particularly at low frequencies.