变刚度曲轴弯扭耦合振动分析

Research for Bending-Torsion Coupling Vibration of a Variable Stiffness Crankshaft System

曲轴作为压缩机的关键部件,其振动形式复杂且相互耦合。针对曲轴旋转时弯曲刚度不断变化的特性,给出了变刚度的曲轴振动模型,推导了弯扭耦合振动的非线性微分方程组并应用多尺度法求解。求解结果和曲轴实例分析表明,由于变刚度的影响,曲轴的弯曲、扭转振动发生更大振幅的耦合振动。相比定刚度解,变刚度曲轴的轴心轨迹波动、弯曲振动振幅明显增大。在扭转振动主共振时,弯曲振动也出现较大振幅,忽略变刚度因素,将造成较大的误差。

Crankshaft has complex and interrelated vibration forms.Considering the time -varying characteristics of the crankshaft＇s bending stiffness, it puts forward an variable bending stiffness cylinder model and a farmula dynamics equations is deduced and solved by multiple-scales method. Result of the theoretical analysis and example calculation shows that variable bending stiffness crankshaft possesses a higher amplitude of bending-torsion vibration and axis orbit. When the rotational frequency equals the natural frequencies of the bending vibration, the bending vibration also appear bigger amplitude. It would result in large errors without variable stiffness.