The influence of load type and endcap shape on the sound radiation of closed and ribbed cylindrical shell structure

The machines mounted in underwater vehicle excite the structure in two ways, namely mechanical force and acoustic excitation, but the sound radiation of the structure due to interior sound source is always underestimated in the noise control. In this paper, the coupled FEM/BEM in modal coordinates is employed to analyze the vibration and sound radiation of the ribbed and closed finite cylindrical shell with free-free boundary condition. Two types of load, namely point radial force and spherical source, and four types of spherical endcaps are considered to investigate the effect of load type and endcap shape on the vibration and sound radiation of the shell. Results show that it is necessary to take the sound source into account in the low-frequency noise control, and the radius of spherical cap has a significant influence on the peak value of the averaged mean-square velocity and sound power in the low frequency range.