APPLICATION OF PASSIVE CONSTRAINED VISCOELASTIC LAYER IN PLATES WITH ACOUSTIC BLACK HOLES

The Acoustic Black Hole (ABH) effect is the phenomenon in which the wave velocity in the thin-walled structure decreases gradually by gradient variation in the geometrical parameters or material behavior, and the wave velocity decreases to zero without reflection in the ideal scenario of a zero-thickness wedge. However, the ideal ABH is hard to achieve in practice, so the truncation of the edge will lead to a non-zero reflection coefficient and weaken the ideal ABH effect. In recent years, a thin viscoelastic layer on the edge is often used to dissipate energy and reduce vibration, but most studies use free damping techniques. Compared with the unconstrained viscoelastic layer (UVL), the passive constrained viscoelastic layer(PCVL) is more efficient, through a constrained layer (CL) on the surface of the viscoelastic layer(VL). In this paper, PCVL is used to improve the efficiency of truncated acoustic black holes in plates. Under the Rayleigh-Ritz framework, a semi-analytical model was presented for the vibration analyses of an ABH plate with PCVL, where the displacement fields are expanded by Gaussian functions. The model is validated through finite element (FEM) simulations. By analyzing the forced vibration of ABH plates with different damping layers, it is observed that a truncated ABH plate with PCVL performs better than an ABH plate with UVL.