ASA 127th Meeting M.I.T. 1994 June 6-10

2aSA2. Vibration damping of large structures induced by attached small substructures each with multiple degrees of freedom.

M. Strasberg

D. Feit

David Taylor Res. Ctr., NSWC, Bethesda, MD 20084-5000

At the previous meeting [J. Acoust. Soc. Am. 94, 1814 (A) (1993)] a relatively simple method was described for estimating the vibration damping introduced into a large structure by a multitude of small substructures compliantly connected to the large structure. The analysis in that talk assumed that the substructures behaved as sprung masses with different but closely spaced frequencies of resonance, each mass having a single frequency of resonance corresponding to one degree of freedom. The analysis is now extended to attached substructures each with multiple degrees of freedom. As an example, calculations are presented of the damping of flexural vibrations induced in a large undamped beam by a large number of small cantilevered strips of gradually varying length attached to the beam. The calculated results are compared with experimental data for this arrangement described some years ago by M. Heckl. [Work supported by ONR.]