<p><i>Various acoustic structures and materials have been developed to improve the characteristics of sound insulation and numerous experiments have been conducted to assess their performances. Because this approach is time-consuming, simulations using the finite element method (FEM) have been proposed to analyze one-dimensional long and narrow acoustic tubes. These tubes have an incidence end and a transmitted end with a test piece located between them. The sound pressures (SPs) in front of and behind the test piece are acquired to calculate the transmission loss. However, the result does not agree exactly with the theoretical value and has to be corrected. The reason for the difference between the results is that the SPs obtained by the FEM include those of both the forward and backward waves. According to the theoretical definition, the sound insulation is calculated using only the forward SPs at both sides. This can be achieved by setting the end of the transmitted side to be a nonreflective boundary. In this paper, to generalize this method, it is determined theoretically that the SPs from the FEM can be separated accurately into the SPs of the forward and backward waves from Helmholtz's equation. Then, the sound insulation characteristics of a flat plate obtained using the proposed theoretical method and the conventional method are compared while assuming that the flat plate is a rigid body. In addition, the validity of the proposed method is confirmed by evaluating the effect of attaching a sound absorbing material to the plate. Furthermore, application of the proposed method to a flat plate with a truss core and an examination of whether a high aspect ratio is advantageous for sound insulation are also presented.</i></p>

Theoretical Study of Sound Insulation Simulations (About Attaching Effect of Sound Absorbing Material and Consideration of Sound Insulation Performance by Height of Origami Core)

Paper Proceedings: https://asmedigitalcollection.asme.org/IDETC-CIE/IDETC-CIE2021/volume/85369

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