ASA 125th Meeting Ottawa 1993 May

4pSA12. Mode localization phenomenon analysis on infinite ribbed plates.

Ten-Bin Juang

Anna L. Pate

Alison B. Flatau

Dept. of Aerosp. Eng. and Eng. Mech., Iowa State Univ., Ames, IA 50011

An analysis of the mode localization phenomenon is demonstrated for disordered structural systems of infinite ribbed plates in air and in water. While for infinite ordered ribbed plates there exist frequency passbands for which vibrations propagate extensively throughout the structure, the introduction of disorder disables the propagation of vibrations to arbitrarily large distances and confines vibrations within a region close to the excitation force. Based upon the mathematical model built in a paper to be published, inertance transfer functions and vibrational responses due to line force excitation are implemented to investigate the passband and stopband characteristics and the localization phenomenon of multiple-rib plates in air and in water. Two facts are confirmed. First, water provides an energy path that reduces the decoupling effect between the bays of ribbed plates observed in the presence of air and consequently, diminishes the localization phenomenon. Second, passbands can merge at certain frequencies, as determined by rib size and dynamic properties, but have nothing to do with the number of ribs or the transmission span. For completeness, acoustic responses are presented for some specific cases of the structural system as well.

All posters will be on display from 1:00 to 5:00 p.m. To allow contributors an opportunity to see other posters, contributors of odd-numbered papers will be at their posters from 1:00 to 3:00 p.m. and contributors of even-numbered papers will be at their posters from 3:00 to 5:00 p.m.