Feature extraction method based on NOFRFs and its application in faulty rotor system with slight misalignment

et al. 2021

Shock and Vibration

Self Cite

In this paper, a pedestal looseness fault model of a rotor-bearing-seal system is established. Under two working conditions of the same direction eccentricity (Working Condition 1) and reverse eccentricity (Working Condition 2), rotor orbits, vibration waveforms, spectrum cascade, and Poincaré maps are used to study the dynamic characteristics of the system when the sliding bearing support is loosened. The influence of speed, the unbalance of two discs, the looseness clearance, and the mass of bearing support on system characteristics are analyzed. The study found that Working Condition 2 is more likely to cause looseness of the bearing support. Moreover, for the rotor system in this paper, the pedestal looseness fault is more likely to occur near the second-order critical speed. Through analysis of the spectrum, it is found that the spectrum of the looseness fault will show multiple frequencies or continuous spectra, and the rotor orbits will appear “cylindrical.”

Section: Introductionmentioning

confidence: 99%

Nonlinear Responses of a Rotor‐Bearing‐Seal System with Pedestal Looseness

Lin

Zhao

et al. 2021

Shock and Vibration

Self Cite

“…Mechanical vibration faults are mainly caused by the vibration of components due to mechanical or electromagnetic factors. It is common in industrial and agricultural machinery, transportation tools and other equipment [1,2]. With the advent of the era of intelligent transportation, how to efficiently and quickly ensure the safe travel of vehicles under the background of internet of vehicles is a problem worth pondering.…”

Section: Introductionmentioning

confidence: 99%

A Vibration Fault Signal Identification Method via SEST

Xiao

et al. 2022

Electronics

(1) Background: with the development of intelligent transportation, effectively collecting and identifying the working state of vehicles is conducive to the analysis and processing of vehicle information by internet of vehicles, so as to reduce the occurrence of traffic accidents. Aiming at the problem of low identification accuracy of the mechanical vibration fault signal, a signal identification method based on time-frequency detection is introduced; (2) Methods: this paper constructs a parameter model of the synchroextracting S transform on the basis of the poor time-frequency concentration of the original S transform; (3) Results: in the case of SNR = −5~+30 dB, compared with other transformations, the Rényi entropy value of SEST is the smallest, and the Rényi entropy value is 0.5246 when SNR = +22 dB; (4) Conclusions: through simulation comparison and analysis, the excellent time-frequency concentration and anti-noise characteristics of the SEST are highlighted, and the rotor vibration fault signals such as rotor misalignment, unbalance and bearing wear are identified by SEST.

“…In the study of rotor-coupling misalignment, the most important thing is to establish a mathematical expression that can simulate coupling misalignment. At present, the main modeling methods of coupling misalignment can be divided into the following three types: (1) According to the geometric relationship and force analysis of misalignment, the expression of excitation force generated by coupling misalignment is obtained [5][6][7][8][9][10]. (2) Based on the Lagrange energy method, the dynamic equation of misalignment coupling-rotor system is established [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Dynamic characteristics of ball bearing-coupling-rotor system with angular misalignment fault

Yang

et al. 2022

Nonlinear Dyn

Self Cite

The rotor misalignment fault, which occurs only second to unbalance, easily occurs in the practical rotating machinery system. Rotor misalignment can be further divided into coupling misalignment and bearing misalignment. However, most of the existing references only analyze the effect of coupling misalignment on the dynamic characteristics of the rotor system, and ignore the change of bearing excitation caused by misalignment.Based on the above limitations, a five degrees of freedom nonlinear restoring force mathematical model is proposed, considering misalignment of bearing rings and clearance of cage pockets. The finite element model of the rotor is established based on the Timoshenko beam element theory. The coupling misalignment excitation force and rotor unbalance force are introduced. Finally, the dynamic model of the ball bearing-coupling-rotor system is established. The radial and axial vibration responses of the system under misalignment fault are analyzed by simulation. The results show that the bearing misalignment significantly influences the dynamic characteristics of the system in the low-speed range, so bearing misalignment should not be ignored in modeling.With the increase of rotating speed, rotor unbalance and coupling misalignment have a greater impact.Misalignment causes periodic changes in bearing contact angle, radial clearance, and ball rotational speed. It also leads to reciprocating impact and collision between the ball and cage. In addition, misalignment increases the critical speed and the axial vibration of the system. The results can provide a basis for health monitoring and misalignment fault diagnosis of the rolling bearing-rotor system.