ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

3pSA2. Effect of mass loading on the dynamic behavior of a three-dimensional truss.

Joseph E. Bondaryk

Ira Dyer

Dept. of Ocean Eng., MIT, 77 Massachusetts Ave., Rm. 5-435, Cambridge, MA 02139

Recent trends in submarine design suggest the use of trusslike structures, connected to the hull by a limited number of attachment points, to support rotating machinery and decks with passive loads. The ratio of the supported mass to the truss mass is high, typically 5--10. This loading must affect the dynamic response of the truss. It is believed that resiliently mounted mass will have a ``fuzzy'' effect on the truss and result in damping of structural waves. The MIT Structural Acoustics Group is making experimental measurements on a 1:15 scale model of a nonpractical, 3D, submarine truss, constructed of 0.5-in. aluminum tubing, up to frequencies of 5 kHz. The dynamic response of two identical trusses, one unloaded and one mass-loaded at a ratio of 5:1, to octave-band noise are measured and compared. The results show the effects of passive and resiliently mounted mass loading on a truss structure. [Research supported by ONR.]