关键词: 非线性响应, 螺旋桨曲轴系统, 扭纵耦合振动, 数值仿真

Abstract: In consideration of propeller, variable mass moment of inertia of linkages and pistons, and coupling effect between torsional and axial vibration, the nonlinear dynamic model of the crankshaft system with 6 linkages, 6 pistons and a propeller is established, in which the axial force equivalent to the transverse force caused by variable mass moment of inertia and pressure on pistons is used. The governing equations of the model demonstrate a strong nonlinear and non autonomous system. By numeric simulation, the time history and frequency spectra of the system are researched at the working speed. It is found that in the spectra of the relative torsional response between propeller and first crank, between fifth crank and sixth crank, two times frequency components are very distinct; base frequency components, six times frequency components and twenty times frequency components appear in the spectra of the relative axial response; four times frequency components, with which the actuating force is applied on the propeller, do not appear. Therefore, in the design of diesel propeller crankshaft system, if the intensity and the vibration response of the system are calculated and analyzed only on the basis of linear dynamic theory, large errors may be caused.

Key words: Coupling effect between torsional and axial vibration, Nonlinear vibration response, Numerical simulation, Propeller crankshaft dynamic system