A combined periodic acoustic black hole beams with wide vibration attenuation bands

An acoustic black hole (ABH) structure has a gradual impedance gradient due to the thickness of the section decreasing as a power law, which shows excellent wave gathering and energy dissipation effect. To enhance the vibration suppression ability, periodic ABHs are proposed recently. A virtual spring-energy method (VEM) is adopted to handle the periodic boundary condition of periodic ABHs. The accuracy of the method is verified through the finite element method. The band gap of infinite periodic ABH beam and vibration transmission of finite periodic ABH beam are analyzed. For finite periodic ABH beams, the size of cells affects the attenuation band of vibration transmission, and the number of cells affects the amplitude. There is a linear superposition characteristic between the attenuation amplitude and the number of cells. The effect of damping layer on beams with different cross sections is also discussed. Finally, a combined ABH beam with damping layers of different cell sizes is proposed to achieve wide transmission attenuation bands.