Low-frequency elastic wave attenuation in a composite acoustic black hole beam

This study discusses the composite acoustic black hole (ABH) beam structure with low-frequency flexural wave attenuation properties. Band structures show that the proposed structure can overcome the limitation of conventional acoustic black holes, which cannot be applied at low frequency. By introducing an ethylene vinyl acetate (EVA) interlayer, the composite beam structure does not reveal the necessary low local stiffness or high stress concentration, vibration modes indicate that flexural wave attenuation still depends on the ABH. Furthermore, the size of the EVA material only affects the upper boundary of the second flexural bandgap but both boundaries of third flexural BG. Elastic constants of different materials have a great effect on the first three BGs. Vibration experiments prove the effect of the composite ABH beam and validate our results. This research has potential applications for controlling vibration propagation, and may be useful in low-frequency vibration filter design.