A study of the friction-induced self-excited vibration in a propeller-shaft system supported by water-lubricated stern-tube bearing is presented. A nonlinear mathematical model of the propeller-shaft system by using the Lagrangian approach in conjunction with the modal superposition technique is formulated to exhibit the excitation mechanism. The model accounts for the lateral-torsional vibrations interaction of the shaft as well as the bearing-shaft friction represented by the Stribeck curve about the low velocity region. Dynamic analyses are carried out using the Newmark method with the Newton-Raphson iterations. With the occurrence of self-excited vibration, all system dynamics considered can be excited, while on-off intermittent motion and limit cycles are also observed. Numerical investigations reveal that the unstable lateral vibration modes are responsible for the occurrence of self-excited torsional oscillations and the lateral-torsional vibrations interaction is a reasonable source to enhance the friction-induced instability.
展开▼
