非稳态非线性油膜力作用下柔性轴裂纹转子的动力特性分析

分析了在动载轴承非稳态非线性油膜力作用下，具有横向裂纹柔性轴Jeffcott转子在非线性涡动影响下的动力特性。通过数值计算表明，在油膜失稳转速前，随着裂纹轴刚度变化比的增大，系统在低转速区域内具有丰富的非线性动力行为，出现倍周期分叉及混沌现象，涡动振幅随转速升高而减小，直到非稳态非线性油膜失稳，在无裂纹转子油膜临界失稳点处发现了类Hopf分叉现象，系统运动由平衡变为拟周期运动；裂纹转子在油膜临界失稳时的系统运动亦为拟周期运动，裂纹转子轴刚度变化对油膜失稳点及油膜失稳之后转子的运动影响不大，转子系统作拟周期运动。

DYNAMIC BEHAVIOR ANALYSIS OF ELASTIC SHAFT ROTOR WITH A CRACK SUPPORTED ON THE UNSTEADY AND NON-LINEAR OIL FILM

An approach about the no-linear whirl dynamic behavior of elastic shaft Jeffcott rotor with a transverse crack, which is supported on the unsteady and no-linear oil film, is presented. The numerical simulation shows that in the region of low rotational speed where the oil-film instability do not occur, period doubling bifurcation and chaos take place as the cracked shaft stiffness alteration ratio increases, and the whirl amplitude decreases with increasing of the rotational speed until the unsteady and non-linear oil-film becomes instable. At oil film critical instability rotational speed of non-cracked rotor, the quasi-Hopf bifurcation phenomenon is detected. The system motion turns to quasi-period from equilibrium, and this is true for cracked-rotor at the cracked rotor oil film critical instability rotational speed. Stiffness change has little effect on the critical instability and motion of the cracked-rotor, and the system motion is quasi-period motion.