An Automaton Fault Diagnosis Based on Shock Response Analysis

2012 ◽  
Vol 226-228 ◽  
pp. 745-748
Author(s):  
Hong Xia Pan ◽  
Ming Zhi Pan ◽  
Run Peng Zhao ◽  
Hai Feng Ren
Keyword(s):  
Frequency Domain ◽  
High Speed ◽  
Energy Analysis ◽  
Signal To Noise Ratio ◽  
Wavelet Packet ◽  
Rapid Identification ◽  
Vibration Response ◽  
Response Analysis ◽  
Machine Vibration ◽  
Diagnosis Method

Shock and vibration response is a particularly important signal to characterize the system state. This paper analyzes the reason of fault generated high speed machine, vibration response mechanism and its frequency characteristic. According to the measured vibration signals, done time and frequency domain features analysis, wavelet packet analysis and frequency domain energy analysis, put forward a kind of fault comprehensive diagnosis method with accurate and rapid identification characteristics, can adapt to the complex vibration response signal with interference and low signal to noise ratio.

Multiharmonic Forced Response Analysis of a Turbine Blading Coupled by Nonlinear Contact Forces

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Christian Siewert ◽  
Lars Panning ◽  
Jörg Wallaschek ◽  
Christoph Richter
Keyword(s):  
Frequency Domain ◽  
Nonlinear Equations ◽  
Forced Response ◽  
Vibration Response ◽  
Contact Forces ◽  
Dynamic Loads ◽  
Response Analysis ◽  
Dynamic Stresses ◽  
Nonlinear Contact ◽  
Turbine Blading

In turbomachinery applications, the rotating turbine blades are subjected to high static and dynamic loads. The static loads are due to centrifugal stresses and thermal strains whereas the dynamic loads are caused by the fluctuating gas forces resulting in high vibration amplitudes, which can lead to high cycle fatigue failures. Hence, one of the main tasks in the design of turbomachinery blading is the reduction in the blade vibration amplitudes to avoid high dynamic stresses. Thus, coupling devices like underplatform dampers and tip shrouds are applied to the blading to reduce the vibration amplitudes and, therefore, the dynamic stresses by introducing nonlinear contact forces to the system. In order to predict the resulting vibration amplitudes, a reduced order model of a shrouded turbine blading is presented including a contact model to determine the nonlinear contact forces. To compute the forced response, the resulting nonlinear equations of motion are solved in the frequency domain using the multiharmonic balance method because of the high computational efficiency of this approach. The transformation from the time domain into the frequency domain is done by applying Galerkin’s method in combination with a multiharmonic approximation function for the unknown vibration response. This results in an algebraic system of nonlinear equations in the frequency domain, which has to be solved iteratively in order to compute the vibration response. The presented methodology is applied to the calculation of the forced response of a nonlinear coupled turbine blading in the frequency domain.

Research of Automobile Engine Fault Diagnosis Based on Wavelet Packet

2012 ◽  
Vol 472-475 ◽  
pp. 795-798
Author(s):  
Min Yong Tong
Keyword(s):  
Fault Diagnosis ◽  
Frequency Band ◽  
Signal Analysis ◽  
Energy Analysis ◽  
Wavelet Packet ◽  
Automobile Engine ◽  
Band Energy ◽  
Diagnosis Method ◽  
S Model ◽  
Frequency Band Energy

A diagnosis method using wavelet packet, frequency band energy analysis and neural network was presented for the automobile engine fault diagnosis. Fault signal of automobile engine was decomposed at different frequency band by wavelet packet. According to the change of frequency band energy, fault frequency band of the automobile engine was found. Fault diagnosis knowledge is described by means of applying T-S model. Results from the experimental signal analysis show that the proposed method is effective in diagnosing the automobile engine faults.

Wavelets base Automatic Extraction Technology for Vibration Signal Characteristics of Hybrid Electric Vehicle Engine

2019 ◽  
Vol 11 (5) ◽  
Author(s):  
Dongfang Song ◽  
Guanfei Yin
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Energy Analysis ◽  
Wavelet Packet ◽  
Vibration Signal ◽  
Domain Analysis ◽  
Extraction Technology ◽  
Vibration Signals ◽  
Engine Vibration ◽  
Signal Characteristics

Traditional automatic characteristic extraction technology of engine vibration signals for hybrid electric vehicles (HEV) only focuses on the analysis of engine vibration signals in time domain and frequency domain. Single time domain analysis or single frequency domain analysis cannot accurately analyse the vibration signals, while both time domain analysis and frequency domain analysis have cross-analysis. As a result, the analysis results are repetitive and conflicting, which makes it difficult to extract the characteristics of engine vibration signals. The final extraction accuracy is not high and the extraction efficiency is low. For this reason, an automatic characteristic extraction technology of HEV engine vibration signal based on wavelet packet energy analysis is proposed. Firstly, the mechanical vibration of engine is converted into corresponding voltage and current signals by various sensors and then converted into digital signals by A/D (analog/digital) conditioner. The data of vibration signals are often mixed with various noises, which have a great impact on the final analysis of vibration signals. Data interception and pre-filtering are adopted. Wave, zero-mean, elimination of trend term and elimination of staggered points are used to pre-treat the vibration signals with mixed noise. Short-Time Fourier Transform (STFT) algorithm is introduced to analyse the pre-processed engine vibration signals and the fundamental properties of the non-stationary vibration signals in actual operation of the engine are obtained. The energy distribution of the analysed engine vibration signal is calculated by the wavelet packet energy analysis method. The calculated parameters of the energy distribution of the wavelet packet are taken as the characteristic parameters of the vibration signal. The vibration signal characteristics of the engine are automatically extracted. The experiment is carried out in the form of comparison with the traditional method. The experimental results show that the time-frequency joint analysis applied in the proposed technology can accurately analyse the essential characteristics of the engine vibration signal of HEV. The wavelet packet energy analysis method can ensure the extraction accuracy of the engine vibration signal characteristics.

Dominant Modals of Wind-Induced Vibration Response for Spherical Kiewitt Cable Dome

2014 ◽  
Vol 1065-1069 ◽  
pp. 1156-1159 ◽  
Author(s):  
De Min Wei ◽  
Di Li ◽  
Ya Qing Liu
Keyword(s):  
Frequency Domain ◽  
Correlation Coefficients ◽  
Frequency Domain Analysis ◽  
Vibration Response ◽  
Induced Response ◽  
Response Analysis ◽  
Computational Results ◽  
Cable Dome ◽  
Wind Induced Vibration ◽  
Wind Induced Vibration Response

Correlation coefficients of mode shape between higher frequency modes and lower frequency modes are given. Then 17 high modes were initially selected as the dominant high modes in the analysis of wind-induced response, and cumulative mode correlation was used to judge the rationality of the method of selecting dominant high modals, so dominant modals of wind-induced response analysis are constructed. Based on these, the wind-induced vibration response of spherical Kiewitt cable dome was analyzed in frequency domain using CQC method. Through analyses of computational results, it is found that the selecting method of dominant modals by using the mode correlation coefficient can be applied in frequency domain analysis for wind-induced vibration response of cable dome structures. If the first 100 modals are considered into the analysis, the computational results obtained will be high precision.

Aeroengine Rub-Impact Fault Diagnosis Based on Wavelet Packet Transform and the Local Discriminate Bases

2012 ◽  
Vol 226-228 ◽  
pp. 740-744 ◽  
Author(s):  
Ya Hui Wu ◽  
Meng Xiao Shan ◽  
Yu Ning Qian ◽  
Xin Liang Li ◽  
Ru Qiang Yan
Keyword(s):  
Fault Diagnosis ◽  
High Speed ◽  
High Performance ◽  
Wavelet Packet ◽  
Integrated Approach ◽  
Wavelet Packet Transform ◽  
Fault Classification ◽  
Time Frequency ◽  
Diagnosis Method ◽  
Optimal Set

With the development of aeroengine towards the direction of high speed and high performance, the clearance between rotor and stator in aerongine is reduced so that the possibility of rub-impact fault is increased. Since rub-impact signals often exhibits non-stationarity, an integrated approach, which combines the wavelet packet transform (WPT) with local discriminate bases (LDB), is presented in this study to diagnose the rub-impact faults. Specifically, the LDB algorithm is used to select an optimal set of orthogonal time-frequency subspaces resulted from WPT, which have the best discriminatory information for aeroengine rub-impact fault classification. Then the desired parameters generated by the LDB vectors were taken as input to a Bayes classifier for identifying rub-impact faults. Experimental results from the aeroengine vibration signals show that the fault diagnosis method can classify working conditions and fault patterns effectively.

scholarly journals Response Analysis of Ladder Beams Under Inertial Moving Load

2018 ◽  
Vol 23 (No 3, September 2018) ◽  
Author(s):  
Hongliang Li ◽  
Bo Zhang ◽  
Yunxuan Gong ◽  
Donghua Wang
Keyword(s):  
High Speed ◽  
Moving Load ◽  
Vibration Characteristics ◽  
Vibration Response ◽  
Response Analysis ◽  
Beam Model ◽  
Inertia Effect ◽  
Moving Loads ◽  
Model Free ◽  
Variable Section

With the continuous development of industry, variable-section beams and high speed moving loads with large mass are widely used. Thus, it is of great significance to study the vibration response of variable-section beam with the consideration of inertia effect. Most past research focuses on the vibration response on uniform beams considering inertial effects, but there is little research on the vibration response of moving loads on variable section beam considering the inertia effect. In this paper, a variable section beam is simplified as a multi-stage ladder beam. Using the Euler-Bernoulli beam model, free-vibration characteristics and forced vibration characteristics of cantilever ladder beam are analysed. Following this step the vibration response considering the influence of the inertia effect is studied and compared with the situation that does not consider the influence of inertia effect. The results show that the mass, velocity, and acceleration of moving loads influence the effect of inertia on the response. Mass is the main factor affecting the results. The inertia effect caused by the acceleration and velocity can be ignored when the mass of moving load is small. The results have good engineering applicability.

Impact of Rail Fastener Looseness on Vertical Dynamic Responses of High-Speed Vehicle and Ballastless Track

2021 ◽  
Author(s):  
Jianbo Li ◽  
Hongmei Shi
Keyword(s):  
Dynamic Response ◽  
Detailed Analysis ◽  
Frequency Domain ◽  
High Speed ◽  
Vibration Response ◽  
Dynamic Responses ◽  
Time Frequency ◽  
Ballastless Track ◽  
Track System ◽  
Track Irregularity

The fastener system is an essential component of the high-speed ballastless track system. A detailed analysis for the effect of fastener looseness on the vertical dynamic response of the vehicle–track coupling system is conducted from the time domain, frequency domain and time–frequency domain in this paper. A fine fastener system model is employed, which includes two spring rods and one rail pad. The preloaded force is proposed to simulate the defect of the fastener, and a looseness coefficient is defined to represent the loose degree of the fastener. First, three fastener system models are introduced into the model, respectively, and the difference in the vehicle–track dynamic is analyzed and compared. The results show that the proposed model is more consistent with the real situation and more suitable to simulate fastener defects. Then, the detailed analysis of vehicle and track dynamic responses is explored in the case of different degrees of loose fasteners and the case of completely loose fasteners. According to the simulation results, there is little impact on the dynamic response of the vehicle–track system when the looseness coefficient is less than 0.9. When the fasteners are completely loosened, the dynamic response of the wheelset and the rail significantly increases. The vibration responses of rail and wheelset enhance with the increase of the number of the completely loose fastener. The loose fasteners affect the low-frequency part of the wheelset vibration response and the high-frequency part of the rail vibration response. Finally, a time–frequency analysis method is used to analyze the system vibration response under the combined effect of the completely loose fastener and the track irregularity. The track irregularity still dominates the excitation of the system, and the vibration response of the wheelset and the rail is more sensitive to the fastener defect at low speed.

Rolling element bearing weak feature extraction based on improved optimal frequency band determination

2018 ◽  
Vol 233 (2) ◽  
pp. 623-634 ◽  
Author(s):  
Rui Yang ◽  
Hongkun Li ◽  
Chaoge Wang ◽  
Changbo He
Keyword(s):  
Frequency Domain ◽  
Frequency Band ◽  
Signal To Noise Ratio ◽  
Wavelet Packet ◽  
Rolling Element Bearing ◽  
Optimal Frequency ◽  
Filter Length ◽  
Iteration Period ◽  
Rolling Element ◽  
Element Bearing

Conventional Kurtosis method represents the statistical property of signal in the time domain. Correlated Kurtosis is proposed that combines the correlation coefficient and Kurtosis in order to indicate the periodicity and impact of signal. In this study, correlated Kurtosis is introduced into frequency domain to improve the recognition accuracy of the optimal frequency band. It does not perform well under the lower signal-to-noise ratio. And then, maximum correlation Kurtosis de-convolution method is used for extracting the approximate impact signal before selecting the optimal frequency band. However, it is limited in diagnosing rolling element bearing fault in the case of the algorithm iteration period is unknown. In addition, filter length also affects the filtering results. To eliminate the confusion, correlated Kurtosis of the frequency domain is applied to iteration period calculation. In this research, a new index is also proposed based on entropy and correlated Kurtosis to optimize the filter length. Then, the full bandwidth of filtered signal is partitioned into several sub-bands according to the refined wavelet packet binary tree. The correlated Kurtosis for each sub-band is calculated. The optimal sub-band for which the correlated Kurtosis is maximal is extracted to analysis. In the end, the efficiency of the new index and the fault diagnosis method are verified by using simulation data and experimental data.

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