A novel fault diagnosis method for rotor rub-impact based on nonlinear output frequency response functions and stochastic resonance

The rub-impact fault of the rotor system is the research object in this paper, and the system is modeled by the finite element method. In the process of the study, the high-order harmonic components appear in the output response of the rotor system, which imply that the rotor system is nonlinear. Nonlinear output frequency response functions (NOFRFs) solve nonlinear problems in the frequency domain and explain these nonlinear phenomena. Based on NOFRFs, a method named weighted contribution rate of NOFRFs (WNOFRFs) is used to improve the weak high-order harmonic components proposed by the authors. In this paper, the multi-parameter optimized genetic algorithm is used to calculate the obstacle parameters of the stochastic resonance (SR) which is used to enhance weak signal components. In view of the fact that both WNOFRFs and SR can improve the weak signal components, a new method of weighted contribution rate of NOFRFs incorporating stochastic resonance (WNS) algorithm is proposed in this paper. Based on the algorithm, the variations of index WS show a trend of approximately linear growth, which indicates that index WS has certain advantages for the fault diagnosis of the rotor rub-impact.