Research on a new diagnosis index for fixed-point rub-impact of rotor system

A model for a rotor system simulated with finite element method and a test bench are established in this paper. The fixed-point rub-impact fault on rotor system is studied (There are six clearances to be discussed). It is found that the nonlinear compositions are contained in the output responses by analyzing these vibration signals of the rotor system with fixed-point rub-impact, which implies that a nonlinear term appears in the system. In order to extract these compositions, a nonlinear method, named weighted contribution rate of nonlinear output frequency response functions (WNOFRFs), is adopted for analyzing the mechanism of these nonlinear problems in frequency domain. Furthermore, the Clenshaw-Curtis numerical integration method and the minimum mutual entropy principle (MMEP) are used to extract the fault diagnosis index J for identifying the fixed-point rub-impact fault of the system. At last, according to the simulation and experiment research, WNOFRFs can improve these higher-order nonlinear characteristics. And these findings prove that the index J has certain advantages compared with other indexes in the diagnosis of the rotor rub-impact fault.