基于模态扩展与谐波分解的转子碰摩故障精确诊断

以某单跨双盘模型转子实验台为例,建立了该转子-轴承系统有限元模型,得到转子系统前两阶固有频率和振型向量等模态参数·基于转子系统碰摩力的周期性假设,利用模态扩展方法,对故障和健康转子系统振动信号的残差矩阵进行傅立叶级数的分频谐波近似,估算得到转子-轴承各节点的碰摩力·根据转子各结点估算碰摩力的频谱、时序以及等效碰摩力幅确定碰摩发生位置,进而对碰摩故障的程度进行定性评估·试验表明,这种方法可以对转子周期性碰摩进行较精确的诊断,并为其他转子-轴承系统故障诊断提供参考·

Precise Diagnosis of Rotor Rubbing Fault Based on Modal Expansion and Harmonic Decomposition

An FEM model of rotor-bearing system was set up for a single-span-two-disc test rig to obtain such model parameters as the first and second order natural frequency and vibration mode vectors. Based on the assumption of periodic rubbing force in rotor system, the rubbing forces onto each node of rotor system are estimated by modal expansion technique and the sub-harmonic decomposition of residual matrix between faulty and faulty-free vibration signals of rotor system through FFT(fast Fourier transformation). The rubbing position is identified through time serials, frequency spectrum and equivalent magnitude of rubbing force on each node, with corresponding extent of rubbing fault evaluated qualitatively. The method proposed is tested on the single-span-two-disc test rig and proved efficient in precise diagnosis of periodic rubbing force in rotor system, and it also provides a reference for other fault diagnosis of rotor-bearing system.