Structures with acoustic black holes (ABH) attracts increasing interests for the effective reduction of vibration and radiated sound with lightweight. Effective frequencies of single ABH element are usually limited to mid-high frequencies because of the structural size effect. Previous researches show that periodic ABH structures can achieve broad sub-wavelength band gaps, thus effectively lowering frequency of vibration and radiated sound reduction. However, how the band gaps affect the transmission loss of ABH structures has not been revealed. This deserves exploration considering the importance and difficulty of sound insulation at low frequency with lightweight in various aerospace and automobile applications. In this paper, the transmission loss (TL) of a periodic plate with acoustic black holes is investigated. Particularly, the effect of band gaps on TL is examined and compared with the case of uniform plate. Results show that band gaps help to increase TL at low frequencies within the mass-law range, promoting applications of periodic plates with ABHs in weight-critical fields with high sound insulation.

Transmission loss; Periodic plates; Acoustics black hole; Band gaps