Free vibrations of finite periodic structures in pass- and stop-bands of the counterpart infinite waveguides

The existence of frequency stop-bands, in which transmission of the vibro-acoustic energy is impossible, suggests that the periodic structures may be used for vibro-isolation. In any technical application, however, only a finite segment of such a structure can be used. This paper is concerned with comparison of the eigenfrequency spectra of finite periodic structures with location of stop-bands for their infinite counterparts. A hierarchy of four mathematical models is considered. In each case, special attention is paid to eigenfrequencies and eigenmodes of a single periodicity cell with appropriate boundary conditions. The influence of the amount of periodicity cells in a finite compound structure on its eigenfrequency spectrum is analyzed. Several features common for the considered models are found and discussed in the context of the existing knowledge on the subject.