Band-gap acústicos en tubos de sección modulada con periodicidades múltiples

B.J. GÓMEZ; C.E. REPETTO; C.R. STIA; R. WELTI

Buenos Aires

Congreso; VI Congreso Iberoamericano de Acústica - FIA 2008; 2008

Asociación de Acústicos Argentinos (AdAA)

In this work, by using a simple version of the impedance method, the acoustic band-gap of a one-dimensional and locally periodic system is studied. This system consists of a duct with modulated section. In the case of small modulation length values compared to the wavelength, it is found that the system reduces to a serial formation of Helmholtz oscillators. In this case, the classic phonon dispersion law corresponding to a monoatomic lattice is obtained. On the contrary, if the wavelength assumes values comparable to the length of the modulation, the typical band structure of semiconductors is obtained. Transmission coefficients are also calculated for a system with two or more repeated structures. It is shown that very selective bands are obtained at specific frequenciesafter a convenient choice of the periods of repetition.