scholarly journals Dynamic Responses of the Metro Train’s Bogie Frames: Field Tests and Data Analysis

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Xuhui He ◽  
Kehui Yu ◽  
Chenzhi Cai ◽  
Yunfeng Zou
Keyword(s):  
Frequency Domain ◽  
Dynamic Characteristics ◽  
Field Tests ◽  
Dynamic Responses ◽  
Discrete Wavelet ◽  
Bogie Frame ◽  
Time Frequency ◽  
Acceleration Signal ◽  
Track Irregularity ◽  
Acceleration Signals

This paper focuses on the dynamic characteristics of the metro train’s bogie frames based on the field test data. The acceleration signals of both motor bogie frame and trailer bogie frame of a standard B-type metro train were measured. Running tests on the Metro line 21 of Guangzhou (China) were carried out. The acquired acceleration signals of bogie frames were analyzed through several methods to identify the dynamic characteristics of the motor and trailer bogies in the time-frequency domain. The spectral analysis and time-frequency representations show that noise components exist in the high-frequency domain of the original signal, especially for the acceleration signal of the motor bogie frame. Then, the soft thresholding process and discrete wavelet transform decomposition process are conducted to obtain a denoised version of the original signals in the time-frequency domain. The vibration frequency domain and energy distribution of bogie frames under different train speeds are analyzed. The track irregularity wavelength of the metro line is calculated and analyzed based on the measured bogie frames’ acceleration signals. The dynamic characteristics of the metro train’s bogie frames in this paper can be adopted as a reference in the track diagnosis of the elevated metro line.

scholarly journals Dynamic Responses of a Metro Train-Bridge System under Train-Braking: Field Measurements and Data Analysis

Sensors ◽  
2020 ◽  
Vol 20 (3) ◽  
pp. 735
Author(s):  
Xuhui He ◽  
Kehui Yu ◽  
Chenzhi Cai ◽  
Yunfeng Zou ◽  
Xiaojie Zhu
Keyword(s):  
Field Measurements ◽  
Dynamic Responses ◽  
Wavelet Coherence ◽  
Distribution Method ◽  
Bogie Frame ◽  
Time Frequency ◽  
Rigid Frame ◽  
Rigid Frame Bridge ◽  
Acceleration Signals ◽  
Bridge System

This paper focuses on the dynamic responses of a metro train–bridge system under train-braking. Experiments were performed on the elevated Metro Line 21 of Guangzhou (China). A continuous, three-span, rigid-frame bridge (42 m + 65 m + 42 m) and a standard B-type metro train were selected. The acceleration signals were measured at the center-points of the main span and one side-span, and the acceleration signals of the car body and the bogie frame were measured simultaneously. The train–bridge system’s vibration characteristics and any correlations with time and frequency were investigated. The Choi–Williams distribution method and wavelet coherence were introduced to analyze the obtained acceleration signals of the metro train–bridge system. The results showed that the Choi–Williams distribution provided a more explicit understanding of the time–frequency domain. The correlations between different parts of the bridge and the train–bridge system under braking conditions were revealed. The present study provides a series of measured dynamic responses of the metro train–bridge system under train-braking, which could be used as a reference in further investigations.

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.

scholarly journals Dynamic Characteristics Analysis with Multi-Directional Coupling in a TBM Mainframe

2019 ◽  
Vol 32 (1) ◽  
Author(s):  
Laikuang Lin ◽  
Yimin Xia ◽  
Zhengguang Li ◽  
Caizhang Wu ◽  
Yongliang Cheng ◽  
...  
Keyword(s):  
Dynamic Model ◽  
Dynamic Characteristics ◽  
Field Tests ◽  
Fatigue Cracking ◽  
Tunnel Boring Machine ◽  
Dynamic Responses ◽  
Water Diversion ◽  
Practical Significance ◽  
Lumped Mass ◽  
Response Characteristics

AbstractThe cutterhead of a full-face rock tunnel boring machine (TBM) is constantly subjected to varying impact and dynamic loads during tunneling processes, resulting in relatively large vibrations that could easily lead to fatigue cracking of the entire machine and affect the tunneling performance and efficiency. To explore the dynamic characteristics of the TBM mainframe, a TBM from a water-diversion project is investigated in this research. According to the TBM vibration transmission route, an equivalent dynamic model of the TBM mainframe is established using the lumped-mass method in which the relevant dynamic parameters are solved. Additionally, the dynamic response characteristics of the TBM mainframe are analyzed. The results indicate that the vibration levels in three directions are approximately the same, the multi-directional vibration of the cutterhead is more intense than that of other components, and the vibration and external excitation exhibit identical change trends. A set of vibration field tests is performed to analyze the in situ dynamic responses of the mainframe and verify the correctness of the dynamic model. The theoretical and measured acceleration values of the TBM mainframe have the same magnitude, which proves the validity of the dynamic model and its solution. The aforementioned results provide an important theoretical value and practical significance for the design and assessment of the TBM mainframe.

Effect of Track Geometric Irregularity on Dynamic Characteristics of Gear Transmission in a Locomotive

2017 ◽  
Author(s):  
Tao Zhang ◽  
Zaigang Chen ◽  
Jie Zhang ◽  
Shunqi Sui ◽  
Cheng Pan
Keyword(s):  
Dynamic Characteristics ◽  
Life Prediction ◽  
Dynamic Performance ◽  
Gear Transmission ◽  
Fatigue Life Prediction ◽  
Dynamic Responses ◽  
Mean Square ◽  
Track Irregularity ◽  
Working Performance ◽  
Statistical Indicators

Gear transmission is a key component in locomotive where it delivers the traction or braking forces between the motor and the wheelset. Its working performance has a direct effect on the operating reliability and safety. Therefore, investigation on the dynamic characteristics of the gear transmission in locomotives is very meaningful. In this study, a gear transmission-locomotive-track spatial coupled dynamic model is established based on the classical locomotive-track coupled dynamics and the gear dynamics theory. Based on this model, the dynamic responses of the gear transmission can be analysed under excitations from different track geometrical irregularity, and the dynamic performance of the gear transmission can be obtained. This paper also studies the effect law of the track irregularity on the vibration of the gear transmission by using statistical indicators RMS (Root Mean Square) and PtP (Peak-to-Peak). The results indicate that the track geometrical irregularity has an obvious impact to the dynamic performance of gear transmission. The dynamic response of the gear transmission will increase violently when the locomotive runs on the track in a worse condition. The results are expected to be capable of providing some references for fatigue life prediction and reliability analysis of the gear transmissions in locomotive.

Influence of Dynamic Characteristics of Wheels between Vehicle with Traditional and Articulated Bogie

2013 ◽  
Vol 732-733 ◽  
pp. 344-347 ◽  
Author(s):  
Hao Shan Yuan
Keyword(s):  
Power Spectrum ◽  
Dynamic Characteristics ◽  
Time Domain ◽  
Interaction Force ◽  
Dynamic Responses ◽  
Dynamics Model ◽  
Bogie Frame ◽  
Vertical Coupling ◽  
Coupling System ◽  
Coupling Dynamics

The wheel-rail combined power spectrum densities are transformed into time domain samples by IFFT method, and add abnormal corrugation samples. The samples were taken as the inputting disturbances of a vehicle-track vertical coupling dynamics model, and the interaction force of wheel/rail is calculated by the models of vehicle with traditional bogie frame and articulated frame of vehicle/track coupling system. Dynamic responses of wheels on corrugation track can be calculated. The results show that wheels vibration intensity of vehicle with articulated bogie is lower.

Control of High Speed Milling Chatter in Simultaneous Time-Frequency Domain

2011 ◽  
Author(s):  
Meng-Kun Liu ◽  
C. Steve Suh
Keyword(s):  
Frequency Domain ◽  
Dynamic Stability ◽  
High Speed ◽  
Adaptive Controller ◽  
System Response ◽  
Discrete Wavelet ◽  
Line System ◽  
High Speed Milling ◽  
Time Frequency ◽  
Milling Chatter

The dynamics governing high speed milling has been extensively explored for decades, both numerically and experimentally. The process loses its dynamic stability and becomes chaotic through either Neimark-Sacker or period doubling bifurcation. While its associated response is still bounded in the time domain, however, it could become unstably broadband in the frequency domain, thus causing the uneven cutting surface on the workpiece and tool damage. A discrete-wavelet-based feedforward adaptive controller is developed to stabilize system response in the time and frequency domains simultaneously. An adaptive controller along with an adaptive filter effective for on-line system identification is implemented in the wavelet domain. By controlling both time and frequency responses, the presented controller design is demonstrated to effectively suppress milling chatter and restore the system back to dynamic stability.

scholarly journals Characterization of Wavelet Decomposition Strain Signal Using the K-Mean Clustering Method

2018 ◽  
Vol 7 (3.17) ◽  
pp. 158
Author(s):  
A A. Rahim ◽  
C H. Chin ◽  
S Abdullah ◽  
S S. K. Singh ◽  
M Z. Nuawi ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Frequency Domain ◽  
Root Mean Square ◽  
Time Domain ◽  
Average Distance ◽  
Industrial Area ◽  
Discrete Wavelet ◽  
Mean Square ◽  
Time Frequency ◽  
Strain Signal

This paper aims to study the characterisation of time-frequency domain to analyse the fatigue strain signal due to weaknesses in time domain and frequency domain approaches. The objectives were to determine the behaviour of strain signal, characterise the fatigue life of strain signal and validate the fatigue life in time-frequency domain. The strain signal was obtained using data acquisition devices and strain gauges on two types of road condition including highway and industrial area. The acquired signals were analysed with time domain, frequency domain and time-frequency domain approaches. In time-frequency domain, the signals were decomposed using 4th Daubechies discrete wavelet transform. To validate the effectiveness of time-frequency approach in characterising vibration fatigue signal, fatigue data was clustered by mapping of the data based on the spectrum energy, root-mean-square and fatigue life obtained. The clustering was performed by comparing the centroid values which both data had five clusters as the optimum data clustering with 0.836 average distance to centroid. From this, the relationship between fatigue life, root-mean-square and spectrum energy can be determined and thus a new fatigue life criterion was developed. 

scholarly journals A dimension reduction technique applied to regression on high dimension, low sample size neurophysiological data sets

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Adrielle C. Santana ◽  
Adriano V. Barbosa ◽  
Hani C. Yehia ◽  
Rafael Laboissière
Keyword(s):  
Sample Size ◽  
Frequency Domain ◽  
High Dimension ◽  
Cross Validation ◽  
Signal To Noise Ratio ◽  
Event Related Potentials ◽  
Discrete Wavelet ◽  
Prediction Errors ◽  
Time Frequency ◽  
Related Potentials

Abstract Background A common problem in neurophysiological signal processing is the extraction of meaningful information from high dimension, low sample size data (HDLSS). We present RoLDSIS (regression on low-dimension spanned input space), a regression technique based on dimensionality reduction that constrains the solution to the subspace spanned by the available observations. This avoids regularization parameters in the regression procedure, as needed in shrinkage regression methods. Results We applied RoLDSIS to the EEG data collected in a phonemic identification experiment. In the experiment, morphed syllables in the continuum /da/–/ta/ were presented as acoustic stimuli to the participants and the event-related potentials (ERP) were recorded and then represented as a set of features in the time-frequency domain via the discrete wavelet transform. Each set of stimuli was chosen from a preliminary identification task executed by the participant. Physical and psychophysical attributes were associated to each stimulus. RoLDSIS was then used to infer the neurophysiological axes, in the feature space, associated with each attribute. We show that these axes can be reliably estimated and that their separation is correlated with the individual strength of phonemic categorization. The results provided by RoLDSIS are interpretable in the time-frequency domain and may be used to infer the neurophysiological correlates of phonemic categorization. A comparison with commonly used regularized regression techniques was carried out by cross-validation. Conclusion The prediction errors obtained by RoLDSIS are comparable to those obtained with Ridge Regression and smaller than those obtained with LASSO and SPLS. However, RoLDSIS achieves this without the need for cross-validation, a procedure that requires the extraction of a large amount of observations from the data and, consequently, a decreased signal-to-noise ratio when averaging trials. We show that, even though RoLDSIS is a simple technique, it is suitable for the processing and interpretation of neurophysiological signals.

scholarly journals Experimental Study on the Nonlinear Dynamic Characteristics of Wire Rope under Periodic Excitation in a Friction Hoist

2020 ◽  
Vol 2020 ◽  
pp. 1-14 ◽  
Author(s):  
Yongbo Guo ◽  
Dekun Zhang ◽  
Xinyue Zhang ◽  
Songquan Wang ◽  
Wan Ma
Keyword(s):  
Dynamic Characteristics ◽  
Nonlinear Dynamic ◽  
Longitudinal Vibration ◽  
Wire Rope ◽  
Dynamic Responses ◽  
Fundamental Wave ◽  
Periodic Excitation ◽  
Time Frequency ◽  
Nonlinear Dynamic Characteristics ◽  
Excitation Frequencies

The nonlinear dynamic responses of a wire rope under periodic excitation in a friction hoisting system are investigated. Longitudinal excitation experiments of different periodic excitation frequencies are performed. The nonlinear dynamic characteristics of the rope, including transverse, longitudinal, and coupled vibrations, are discussed with time-frequency analysis. The results show that the transverse vibration is a forced vibration following the excitation, while the longitudinal vibration shows a complex, random vibration state. The vibration amplitude and intensity deviate significantly from their linear trend (superharmonic resonance) at some excitation frequencies, and this deviation indicates the typical nonlinear multiorder natural frequency characteristics. The lifting motion can lead to additional corrugated high-order harmonics and cause a fundamental wave distortion of low-frequency excitation. Experimental evidence for the coupling characteristics of the transverse-longitudinal rope vibration in the lifting process is found.

scholarly journals Time Frequency Analysis of Wavelet and Fourier Transform

2020 ◽  
Author(s):  
Karlton Wirsing
Keyword(s):  
Signal Processing ◽  
Fourier Transform ◽  
Wavelet Transform ◽  
Frequency Domain ◽  
Frequency Analysis ◽  
Discrete Wavelet ◽  
Continuous Wavelet ◽  
Time Frequency ◽  
Efficient Access ◽  
The Fourier Transform

Signal processing has long been dominated by the Fourier transform. However, there is an alternate transform that has gained popularity recently and that is the wavelet transform. The wavelet transform has a long history starting in 1910 when Alfred Haar created it as an alternative to the Fourier transform. In 1940 Norman Ricker created the first continuous wavelet and proposed the term wavelet. Work in the field has proceeded in fits and starts across many different disciplines, until the 1990’s when the discrete wavelet transform was developed by Ingrid Daubechies. While the Fourier transform creates a representation of the signal in the frequency domain, the wavelet transform creates a representation of the signal in both the time and frequency domain, thereby allowing efficient access of localized information about the signal.

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