Abstract
Sound-insulation model provides a straightforward way to describe sound transmission behaviours of the thin-walled structures in engineering applications. The sound transmission characteristics depend on the parameters of incident wave, such as incident wave amplitude and incident angles. However, this model is limited when the sound source is located in an enclosed space (e.g., noise source in underwater cabins), because it is difficult to obtain incident angles especially in the high-frequency range. In this paper, we develop a simply analytical model that can effectively study the sound transmission from an enclosed shell with internal acoustic excitation. In order to extend the application of the sound-insulation model to a submerged shell, the structural vibration equation is firstly simplified to the plate vibration equation. Then, the sound pressure near the inner surface of the shell is decomposed into an expansion of orthogonal cavity eigenmodes, and each cavity mode is replaced by two pairs of incident plane waves. Finally, the acoustic transmission loss can be obtained by substituting the parameters of incident waves into the sound-insulation model. Numerical results show that the sound transmission for the fundamental cavity mode (0, 0, 0) can be explained by the normal incidence in the sound-insulation model, while every other modes corresponds to a group of oblique incident plane waves whose incident angles decrease monotonically with the increase of frequency. In addition, it can be observed that the total reflection phenomenon in the sound-insulation model is consistent with the low radiation efficiency of the high order modes in the shell model.
Highlights
Thin cylindrical shells are the practical elements of various engineering structures such as pipes, space shuttles, car industry, aircraft and ship hulls[1,2,3,4]
It can be observed that the transmission loss (TL) of different cavity modes is basically consistent with the normal incidence in high-frequency range, there are some deviations near the resonant frequencies of the shell
The sound-insulation model has been extended to predict the sound transmission of a submerged cylindrical shell
Summary
Thin cylindrical shells are the practical elements of various engineering structures such as pipes, space shuttles, car industry, aircraft and ship hulls[1,2,3,4]. The classical thin shell theories[5,6,7] provided the basis for studying the sound transmission problem of cylindrical structures. Fuller[8] presented the acoustic radiation characteristics of infinite cylindrical tube excited by an internal sound source, calculating shell mobility, far-field radiated pressure directivity and transmission loss. The sound insulation theory[15] is applicable to sound transmission prediction for thin-walled structures. Mu et al [21] achieved higher transmission loss by using damping materials In these cases, sound insulation theory has been developed and applied to semi-infinite sound insulation structures. The sound insulation model is used to fast predict the sound transmission for a closed cylindrical shell as an alternative method in highfrequency range.
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