Finite periodic structure of beam for low frequency structure-borne sound attenuation

Unwanted vibration in ships, aircraft and buildings is often caused by the operation of machinery and transmitted into the structure through connected beams. The attenuation of vibrational power transmission in low frequencies has been a difficult problem for a long time. Recently, a series of studies about the elastic wave propagation in locally resonant sonic materials have found that phonon-like acoustic structures can have even better sound attenuation performances than before in a lower range of frequencies due to phonon resonance and Bragg interference phenomena. It is also supposed to effectively attenuate low-frequency vibrational waves in a beam-type one dimensional system by using the periodic phonon structure, the decay and transform of flexural waves in a beam with ternary locally resonant elements attached is studied in this paper.