scholarly journals Effect of wheel polygonalization on the Degree of Non-linearity of dynamic response of high-speed vehicle system

2021 ◽  
pp. 002029402110354
Author(s):  
Chen Shuangxi ◽  
Ni Yanting
Keyword(s):  
Dynamic Response ◽  
Health Monitoring ◽  
Extraction Method ◽  
High Speed ◽  
Vibration Response ◽  
High Speed Train ◽  
Coupled Dynamics ◽  
Vehicle System ◽  
Parameters Extraction ◽  
Non Linear

Polygonalization of the wheel describes the growth of out-of-round profiles of the wheels of railway vehicle. This problem was identified in the 1980s but its mechanism is still not well understood. The wheel-rail disturbance formed by wheel polygonalization will accelerate the fatigue fracture of the key parts of rail vehicles and seriously threaten the safety of rail vehicle. This fact has led to significant efforts in detecting and diagnosing wheel polygonalization, in particular in setting the criteria for health monitoring. Currently, the time-domain feature parameters extraction method based on data statistics and frequency-domain feature parameters extraction method based on spectrum estimation are widely applied to detect wheel polygonalization. However, the basis of spectral estimation is the Fourier transform, which is not good at dealing with non-linear vibration systems (such as vehicle-track coupled system). Aiming at the wheel polygonalization problem existing in high-speed train, the non-linear extent of vibration response of vehicle system caused by wheel polygonalization is analyzed based on vehicle-track coupled dynamics and adaptive data analysis method. A typical high-speed train model is established according to the vehicle-track coupled dynamics theory. The wheel polygonalization model is introduced and vehicle system vibration response is calculated by numerical integration. The vibration response signal is decomposed by empirical mode decomposition (EMD) to produce the intrinsic mode functions (IMFs). By calculating the intra-wave frequency modulation of IMFs, that is, the difference between instantaneous and mean frequencies and amplitudes, the non-linearity of the dynamic response is quantified. Influences of wheel polygonalization on the non-linearity of steady-state and unsteady vibration responses of vehicle system are analyzed in detail. An objective criterion for wheel polygonalization health monitoring based on Degree of Non-linearity is proposed, which provides an effective tool for prognostics and health management of trains.

Motor car–track spatial coupled dynamics model of a high-speed train with traction transmission systems

2019 ◽  
Vol 137 ◽  
pp. 386-403 ◽  
Author(s):  
Zhiwei Wang ◽  
Guiming Mei ◽  
Qing Xiong ◽  
Zhonghui Yin ◽  
Weihua Zhang
Keyword(s):  
High Speed ◽  
High Speed Train ◽  
Dynamics Model ◽  
Transmission Systems ◽  
Coupled Dynamics

scholarly journals Hydrogeological assessment of non-linear underground enclosures

2021 ◽  
Author(s):  
Estanislao Pujades
Keyword(s):  
High Speed ◽  
Retaining Walls ◽  
The State ◽  
High Speed Train ◽  
Diagnostic Plots ◽  
Pumping Wells ◽  
Groundwater Response ◽  
Non Linear ◽  
Effective Conductance ◽  
Using Data

Excavations below the water table are usually undertaken by combining the protection of retaining walls with dewatering by pumping wells. Severe difficulties may arise if the retaining walls have defects. Therefore, their state must be determined and, if needed, the defects repaired or the dewatering system redesigned. The state of underground retaining walls can be evaluated using hydrogeological methods, but these methods are well-established only for linear excavations. The objective of this work is to propose a procedure to evaluate the state of non-linear underground enclosures by analysing the groundwater response to pumping inside the enclosure. The proposed method, which is based on diagnostic plots (derivative of drawdown with respect to the logarithm of time), allows (1) determining if an underground non-linear enclosure has isolated openings or numerous defects and (2) computing its effective conductance or effective hydraulic conductivity. The methodology is tested with data collected during the excavation of a shaft required for the construction of the high speed train (HST) tunnel in Barcelona, Spain. The procedure can be applied using the wells drilled for dewatering. Although a test before the excavation is recommended to evaluate the underground retaining walls (Watertightness Assessment Test), the method can be applied using data collected at the beginning of the dewatering stage.

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