Research Information System
World Academy of Science, Engineering and Technology, New York, United States Of America, 02 January 2023, vol.17, (Full Text)
—Correct measurement of a structural damping value is
an important issue for the reliable design of the components exposed
to vibratory and noise conditions. As far as a vibrating beam technique
is concerned, the specimens under the test somehow are interacted with
measuring and exciting devices, and also with boundary conditions of
the test set-up. The aim of this study is to propose a vibrating beam
method that offers a non-contact dynamic measurement of solid beam
specimens. To evaluate the possible effects of the clamped portion of
the specimens with clamped-free ends on the dynamic values
(damping and the elastic modulus), the same measuring devices were
used, and the results were compared to those with the free-free ends.
First, the governing equations of beam specimens related to the freefree and clamped-free boundary conditions were expressed to be able
to find their natural frequencies, flexural modulus and damping values.
To get a clear idea of the sensitivity of the boundary conditions to the
damping values at low, medium and high levels, representative
materials were subjected to the tests. The results show that the
specimens with low damping values are especially sensitive to the
boundary conditions and that the most reliable structural damping
values are obtained for the specimens with free-free ends. For the
damping values at the low levels, a deviation of about 368% was
obtained between the specimens with free-free and clamped-free ends,
yet, for those having high inherent damping values, comparable results
were obtained. It was obvious that the set-up with clamped-free
boundary conditions was not able to produce correct/reliable damping
values for the specimens with low inherent damping.