A vibro-acoustic analysis method of a flexible propulsion shaft–shell coupled system under multi-source excitations

Vibro-acoustic characteristics of the propulsion system should greatly affect the working performance of underwater vehicles. Most existing studies only considered single propulsion shaft or shell, which used single excitation source or ideal fixed boundary conditions. The coupled dynamics and acoustic responses induced by the combined flexible shaft-shell excitations cannot be fully captured. The present work conducts a vibro-acoustic analysis method for a coupled flexible propulsion shaft-shell (FPSS) system. The multiple excitation sources in the propulsion shaft are considered, which include the motor excitations, bearing excitations and shaft excitations. The governing equations of the structural components are derived by using the energy method. The exterior acoustic field is modeled according to the spectral boundary element method. The developed dynamic model can completely describe the coupled vibro-acoustic behaviors of the FPSS system. A test is also introduced to validate the accuracy of the proposed method. The results may provide some theoretical support for predicting the vibro-acoustic responses of the propulsion systems in the underwater vehicles.