Abstract
Using the active feedback control system on the elastic wave metamaterial, this research concentrates on the sound transmission with the dynamic effective model. The metamaterial is subjected to an incident pressure and immersed in the external mean flow. The elastic wave metamaterial consists of double plates and the upper and lower four-link mechanisms are attached inside. The vertical resonator is attached by the active feedback control system and connected with two four-link mechanisms. Based on the dynamic equivalent method, the metamaterial is equivalent as a single-layer plate by the dynamic effective parameter. With the coupling between the fluid and structure, the expression of the sound transmission loss (STL) is derived. This research shows the influence of effective mass density on sound transmission properties, and the STL in both modes can be tuned by the acceleration and displacement feedback constants. In addition, the dynamic response and the STL are also changed obviously by different values of structural damping, incident angle (i.e., the elevation and azimuth angles) and Mach number of the external fluid with the mean flow property. The results for sound transmission by two methods are compared, i.e., the virtual work principle for double plates and the dynamic equivalent method corresponding to a single one. This paper is expected to be helpful for understanding the sound transmission properties of both pure single- and double-plate models.
Highlights
Phononic crystals have received a great deal of attention since nearly two decades ago [1,2,3]
Elastic wave metamaterials have been widely applied to the acoustic fields, e.g., sound radiation [11, 12], nonreciprocal wave propagation [13], acoustic clock [14,15,16] and sound transmission [17, 18]
The sound transmission through a double-panel lined with poroelastic material in the core was studied, and the results showed the influence of external mean flow on the sound transmission loss (STL) [31]
Summary
Phononic crystals have received a great deal of attention since nearly two decades ago [1,2,3]. Huang and Sun [19] studied an acoustic metamaterial model with effective mass density and Young’s modulus They found that the elastic wave propagation displayed a peculiar elastic wave motion in the region of double negative characteristics. The sound transmission through a double-panel lined with poroelastic material in the core was studied, and the results showed the influence of external mean flow on the sound transmission loss (STL) [31]. The effective medium method was not applied to show the STL properties, and the external mean flow was not taken into account. We present the influences of structural damping, Mach number and incident angle on the STL, and show the STL comparison between the virtual work principle in our previous investigation [42] and the dynamic equivalent result in this work
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