基于恒位移测试的转子系统非线性支承刚度参数辨识研究

Nonlinear Stiffness Parameter Identification of Rotor Support Based on Constant-amplitude Displacement Test

采用基于正弦扫频技术的恒位移测试方法来获取转子支承系统在一系列恒定位移幅值响应下的频响函数,并辨识转子支承的非线性刚度参数。首先对转子支承系统进行两端支承状态下的模态分析,得到转子系统在线性支承条件下的模态;然后采用正弦激励进行仿真测试,对转子支承进行不同水平的恒位移测试,通过模态分析得到不同响应水平下的模态参数,建立等效非线性参数与响应之间的关系,再结合等效线性化理论,识别非线性刚度参数。

A specially developed constant-amplitude displacement test is adopted in the measurement of the frequency response functions (FRFs) in a rotor-bearing system with specified constant-amplitude displacement responses. The FRFs experimentally measured are subsequently used for identifying the structural nonlinearity of the rotor support. In the method, the modal analysis is performed for the rotor with bearing support and the linear modal parameters of a rotor-bearing system are acquired;then, the sinusoidal excitation is used for simulation test, and a constant-amplitude displacement test is used to identify the nonlinear stiffness index from the measured FRFs of the rotor-bearing system. The sinusoidal force excitation is used to ensure the constant amplitudes displacement through adjusting the amplitudes of the force over its frequency range. The rotor system with the nonlinear support is designed and tested to verify the effectiveness of the method.