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为了弥补有限元方法预测含局部非线性的双转子系统动力特性的不足,借助有限元软件和固定界面模态综合法,建立了高维双转子系统非线性动力学模型,随后利用Newmark算法思想提出了一种隐式时域求解该问题的方法,该方法的求解效率主要取决于非线性力处的自由度个数.在考虑挤压油膜阻尼器非线性力和中介轴承非线性力的基础上,研究了双不平衡激励作用下的反向旋转双转子系统的非线性动力响应特性.研究表明:系统响应中除内、外转子自转频率外,出现了2个自转频率的组合频率;随中介轴承径向游隙的增加,系统转速分岔图中出现了分岔和混沌现象,且临界转速略有下降;系统轴心轨迹呈花瓣状,与试验结果基本吻合.
In order to make up for the deficiency of the finite element method in predicting the dynamic characteristics of a two-rotor system with local nonlinearity, the nonlinear dynamic model of the high-dimensional two-rotor system is established by means of finite element software and fixed interface modal synthesis method. Then, using the Newmark algorithm, According to the method of solving this problem in implicit time domain, the solving efficiency of this method mainly depends on the number of degrees of freedom in the nonlinear force.On the basis of considering the nonlinear force of the squeeze film damper and the nonlinear force of the intermediate bearing, The nonlinear dynamic response of a double-rotor system with double-unbalanced excitation is studied. The results show that the combined frequency of two rotating frequencies appears in the system response except for the rotation frequency of the inner rotor and the outer rotor. When the clearance increases, bifurcation and chaos appear in the bifurcation diagram of the system speed, and the critical speed decreases slightly. The system trajectory is petal-shaped, which basically agrees with the test results.