scholarly journals A Proposed Bearing Load Identification Method to Uncertain Rotor Systems

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Wengui Mao ◽  
Nannan Zhang ◽  
Dan Feng ◽  
Jianhua Li
Keyword(s):  
Transient Response ◽  
Perturbation Analysis ◽  
Mean Value ◽  
Rotor System ◽  
Uncertain Parameters ◽  
Load Identification ◽  
Analysis Method ◽  
Interval Analysis Method ◽  
Identification Method ◽  
Bearing Load

Bearings are considered as important mechanical components in rotating machines. Bearing load is used as an indication of monitoring rotor system health, but there are interval and probability uncertain parameters in the process of obtaining bearing load from the rotor system. A bearing load strip enclosed by two bounding distributions is then formed, rather than a single distribution that we usually obtain through the load identification method for a deterministic rotor system. In this paper, a computational inverse approach that combines the interval and perturbation analysis method with regularization is presented to stably identify bearing load strip. Using an interval analysis method, a calculated transient response of the rotor structure only subjecting to the bearing load can be approximated as a linear function of the interval parameters in the rotor system. The perturbation analysis method based on Taylor expansion is used to transform the problem of the bearing load identification involving in probability parameters into two kinds of certain inverse problem, namely, the bearing load identification combining the mean value of uncertain parameters with calculated transient response function and the sensitivity identification of bearing load to each probability parameter. Regularization is used to overcome ill-posedness of bearing load identification arising from the noise-contaminated observed response. A rotor system with two bearings is investigated to demonstrate the effectiveness and accuracy of the presented method.

INTERVAL AND SUBINTERVAL ANALYSIS METHODS OF THE STRUCTURAL ANALYSIS AND THEIR ERROR ESTIMATIONS

2006 ◽  
Vol 03 (02) ◽  
pp. 229-244 ◽  
Author(s):  
Y. T. ZHOU ◽  
C. JIANG ◽  
X. HAN
Keyword(s):  
Interval Analysis ◽  
Taylor Expansion ◽  
Truncation Error ◽  
Estimation Methods ◽  
Uncertain Parameters ◽  
Analysis Method ◽  
Interval Analysis Method ◽  
Analysis Methods ◽  
Second Derivatives ◽  
Error Estimations

In this paper, the interval analysis method is introduced to calculate the bounds of the structural displacement responses with small uncertain levels' parameters. This method is based on the first-order Taylor expansion and finite element method. The uncertain parameters are treated as the intervals, not necessary to know their probabilistic distributions. Through dividing the intervals of the uncertain parameters into several subintervals and applying the interval analysis to each subinterval combination, a subinterval analysis method is then suggested to deal with the structures with large uncertain levels' parameters. However, the second-order truncation error of the Taylor expansion and the linear approximation of the second derivatives with respect to the uncertain parameters, two error estimation methods are given to calculate the maximum errors of the interval analysis and subinterval analysis methods, respectively. A plane truss structure is investigated to demonstrate the efficiency of the presented method.

Active Control by Piezoelectric Material Applied to Dynamic Analysis for Suppression of Panel with Uncertain Parameters

2013 ◽  
Vol 431 ◽  
pp. 301-305 ◽  
Author(s):  
Bo Fang ◽  
Guo Qing Jiang ◽  
Ye Wei Zhang ◽  
Jian Zang
Keyword(s):  
Vibration Control ◽  
Active Control ◽  
Active Vibration Control ◽  
Composite Panel ◽  
Uncertain Parameters ◽  
Analysis Method ◽  
Control Effect ◽  
Interval Analysis Method ◽  
Active Vibration ◽  
Air Speed

This paper studied the dynamic suppression problems of active control of composite panel with uncertain parameters. Considering uncertain factors of panel, finite element vibration dynamic model is established for active vibration control, through interval analysis method to estimate panel in active control of vibration critical air speed and flutter amplitude, to this determined active suppression effects of panel, numerical simulation indicate that through with Piezoelectric patches as active vibration control, the panel with uncertain parameters of whole interval of vibration critical wind speed were changed from vibration to convergence, showing that the control effect was significant.

Dynamic Response Analysis of Rotor System With Uncertain Parameters via Interval Analysis Method

2012 ◽  
Author(s):  
Jie Hong ◽  
Jun Wang ◽  
Meng Chen ◽  
Yanhong Ma
Keyword(s):  
Dynamic Response ◽  
Interval Analysis ◽  
Operating Conditions ◽  
Response Analysis ◽  
Superposition Method ◽  
Uncertain Parameters ◽  
Analysis Method ◽  
Operating Cycle ◽  
Interval Analysis Method ◽  
Modal Superposition

The support stiffness and connecting structure stiffness change with different assembly conditions and operating conditions. The phase and amount of rotor unbalance in different operating cycle changes due to wear of blade tip and connecting structures in different working cycles. These parameters which have significant effect on rotordynamics are “uncertain but bounded”, in another word, the distributions of the parameters are unknown, but the intervals of uncertain parameters are always got easier. An interval analysis method, which solves the dynamic response with these uncertain parameters, has presented. Based on interval mathematics and modal superposition method, interval analysis method simplifies the uncertain parameters to interval vectors so that it can get the intervals within which the dynamic response varies when less information of structure is known. The interval analysis method is efficient under the condition that probability approach cannot work because of small samples and sparse statistics characteristics. The formulation of rotor dynamic response using interval modal superposition analysis method is formulated. A numerical example of comparison between interval analysis method and Monte Carlo method is given, and the results illustrate the interval analysis method.

Interval Analysis Method for Rotordynamic With Uncertain Parameters

2011 ◽  
Author(s):  
Yanhong Ma ◽  
Peng Cao ◽  
Jun Wang ◽  
Meng Chen ◽  
Jie Hong
Keyword(s):  
Perturbation Method ◽  
Interval Analysis ◽  
Operating Conditions ◽  
Small Samples ◽  
Squeeze Film ◽  
Uncertain Parameters ◽  
Analysis Method ◽  
Interval Analysis Method ◽  
Different Temperatures ◽  
Interval Perturbation Method

The support stiffness and connecting structure stiffness which has significant effect on rotordynamics change with different assembly conditions and operating conditions. For example, the squeeze film stiffness changes with different film force, and the elastic support stiffness changes with different temperatures. These parameters are “uncertain but bounded”, in another word, the distributions of the parameters are unknown, but the intervals of the uncertain parameters are always got easier. An interval analysis method, which solves the rotordynamics with these uncertain parameters, is presented. Based on interval mathematics and perturbation method, interval analysis method simplifies the uncertain parameters to interval vectors so that it can get the intervals within which the rotordynamics varies when less information of structure is known. The interval analysis method is efficient under the condition that probability approach cannot work because of small samples and spare statistics characteristics. The formulation of natural frequencies of rotor using interval perturbation analysis method is formulated. A numerical example of comparison between interval perturbation method analysis and monotonic method is given. The rotordynamic analysis of a turbofan rotor is performed with this method, and the test data validates the numerical results.

Interval Analysis on Aero-Engine Rotor System With Misalignment

2015 ◽  
Author(s):  
Cun Wang ◽  
Yanhong Ma ◽  
Dayi Zhang ◽  
Jie Hong
Keyword(s):  
Interval Analysis ◽  
Second Harmonic ◽  
Joint Stiffness ◽  
Element Model ◽  
Rotor System ◽  
Operating Conditions ◽  
Analysis Method ◽  
Interval Analysis Method ◽  
Frequency Components ◽  
Different Characteristics

Misalignment is a usual phenomenon in rotating machines. The rotor centerlines are not collinear at the couplings and the rotors operate in incorrect axial positions in a multi-span rotor. The effects of misalignment of flexible rotor system are summarized as the variation of joint stiffness and additional misalignment excitation force based on the dynamic model established. The variation of joints stiffness is difficult to describe, meanwhile the misalignment excitation and rotor unbalance changes with different assembly and operating conditions. The distributions of these parameters which have significant effect on rotor dynamics are unknown, but the intervals of uncertain parameters are usually easier to get. An interval analysis method based on Taylor expansion and direct integration, which solves the dynamic response of rotor system under complex excitations including misalignment and multi unbalance with different frequencies and excitation points is presented. The differential equation of rotor system is formulated by combination of the matrixes of an actual rotor system finite element model and interval excitation vectors. The responses of a single spool and two spools with misalignment and unbalance are calculated by the interval analysis method. The results indicate that the method is effective and reflects some dynamic influence of misalignment and unbalance on rotor system. Second harmonic frequency appears, and rotor orbit is irregular. The response reflects the uncertain interval distribution characteristics, and the frequency components on different locations of the rotor have different characteristics.

Transient Vibration of High-Speed, Lightweight Rotors Due to Sudden Imbalance

1983 ◽  
Vol 105 (3) ◽  
pp. 480-486 ◽  
Author(s):  
M. Sakata ◽  
T. Aiba ◽  
H. Ohnabe
Keyword(s):  
Transient Response ◽  
High Speed ◽  
Rotor System ◽  
Response Analysis ◽  
Transient Vibration ◽  
Flexible Shaft ◽  
Shaft System ◽  
Transient Response Analysis ◽  
Flexible Disk ◽  
Blade Loss

In the field of rotor dynamics, increased attention is being given to the transient response analysis of the rotor, since the effects of impact loading and vibrations of the rotor arising from blade loss can be studied by a time transient solution of the rotor system. As recent trends in rotating machinery have been directed towards lightweight, high-speed flexible rotors, the effect of flexibility on transient response analysis is becoming of increasing importance. In the present paper, a transient vibration analysis is carried out on a flexible-disk/flexible-shaft system or rigid-disk flexible-shaft system subjected to a sudden imbalance that is assumed to represent the effect of blade loss. To solve the basic equation governing a rotating flexible disk the Galerkin’s method is used, and the equation of motion of the rotor system is numerically solved by employing the Runge-Kutta-Gill’s method. Experiments were conducted on a model rotor having a blade loss simulator; the shaft vibrations were also measured. The validity of the anaytical results was demonstrated by comparison with the experimental results.

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