A dynamic model for a shell-propulsion shaft system considering the shell and shaft flexibilities

The shell flexible deformation will affect the dynamics of the shell-propulsion shaft system. Most previous studies were only focused on the dynamics of flexible shaft systems. Few studies considered the flexible deformations of the shell. This work presents a shell-propulsion shaft system dynamic model considering the shell and shaft flexibilities. The shell-propulsion shaft system in this work consists of one propeller, one shaft, one conical shell, one four-point contact bearing, and one deep groove ball bearing. The shaft dynamic model is established based on Timoshenko beam theory. The conical shell dynamic model is established based on the Kirchhoff-Love shell theory. The propeller and bearing dynamic models are given by using the lumped parameter method. The proposed shell dynamic model is compared with the finite element method (FEM). An experimental validation is conducted to prove the correctness of the propulsion shaft dynamic modeling method. The results obtained by the models with and without considering the shell flexibility are compared. Finally, the effect of the eccentricity error on the shaft and shell vibrations is analyzed.