Broadband transient vibro-acoustic prediction and control for the underwater vehicle power cabin with metamaterial components

In this study, to address the problem of insufficient research on the transient noise of a power section for underwater vehicles, the vibration and acoustic radiation characteristics of a power cabin under transient impact loading are predicted based on the coupled time-domain finite element method and boundary element method (FEM/BEM). Corresponding experimental tests of vibration and acoustic radiation in air are carried out, and the trend of the numerical results based on the time-domain FEM/BEM better agrees with the test results, which verifies the correctness of the numerical model. Furthermore, the transient impact response has broadband and random characteristics, which significantly affect the acoustic stealth performance of underwater vehicles. Thus, star-shaped metamaterial components are designed for broadband transient vibration and noise control in this paper. The band gap properties of the star-shaped functional elements are calculated, and the vibration attenuation characteristics of the star-shaped metamaterial components are evaluated by the indices of the impact isolation coefficient and the vibration level difference (VLD). The vibration and noise reduction properties of the power cabin with star-shaped metamaterial components are analyzed in terms of the insertion loss and overall level. The results show that the vibration and acoustic radiation of a power cabin with star-shaped metamaterial components are significantly reduced at the band gap frequency, especially at 1500-4500 Hz, the maximum attenuation of sound pressure up to 75 dB. Compared with those in the power cabin with original components, the overall sound pressure levels in air and in water in the power cabin with star-shaped metamaterial components are 15.78 dB and 19.21 dB lower, respectively. Finally, the vibration and noise reduction characteristics of the power cabin with star-shaped metamaterial components are verified experimentally. In this paper, prediction, test and control steps for the vibration and noise of a power cabin for underwater vehicles under transient impacts are established, which provide support for the study of transient vibration and acoustic radiation in underwater vehicles.