ACOUSTIC ELASTIC STOP-BAND INTERACTION IN WAVE-GUIDES INVOLVING 2 PERIODICITIES/

A structure with two periodicities can couple up to six modes under a case of simultaneous resonance resulting in a stop-band interaction. T he method of multiple scales is employed to analyze the modal coupling in a two-dimensional acoustic duct with rigid periodically undulated walls as well as ill an elastic plate having periodically corrugated o uterfaces, leading to the coupled-mode equations. The comparison betwe en the three possible cases of interaction under simultaneous resonanc e an given in terms of the power reflection coefficient spectrum as a function of frequency. The strength of the stop-band interaction is fo und to be strongly related to the number of direct couplings between t he incident and reflected modes. (C) 1997 Acoustical Society of Americ a.