Vibro-Acoustic Analysis of an Underwater Cylindrical Shell with Internal Structures and a Comparison with Experiment

Abstract

In this work, the low-frequency vibration response and full-band acoustic radiation characteristics of an underwater reinforced cylindrical shell with internal structures are studied by combining the FEM with SEA. The stiffened cylindrical shell contains internal structures such as the F-shape plates and the support valve frames. The exciting sources have two different exciting forces corresponding to two experimental conditions. In the low-frequency band, the FEM was employed, and in the medium and high-frequency bands, the SEA was used. A comparison of the numerical results and the experiment shows that they agree well. The FEM and SEA give better results at [1,1k] Hz and [1k,10k] Hz, respectively. Due to mesh quality limitations, the FEM is not favorable for medium and high-frequency calculations. The SEA focuses on the structural mean power flow but cannot obtain position-specific vibrational responses. The results show that the internal excitation source mainly causes the structural vibration and sound radiation and are closely related to the free vibration characteristics of the structure. In addition, with the increase in frequency, the circumferential sound pressure level of the underwater structure has more substantial directivity.