scholarly journals Analysis on the Effects of Material Parameters on the Fatigue Performance of Novel Anticorrugation Elastic Rail Clips

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Ping Wang ◽  
Jun Lu ◽  
Caiyou Zhao ◽  
Li Yao ◽  
Xuanhui Ming
Keyword(s):  
Plastic Deformation ◽  
Fatigue Life ◽  
Natural Frequency ◽  
Coupling Model ◽  
Dynamic Responses ◽  
Clamping Force ◽  
Vibration Acceleration ◽  
Rail Corrugation ◽  
Material Parameters ◽  
Selection Of

A novel elastic rail clip was obtained through size improvement based on the II-type elastic rail clips to solve the fatigue failure of elastic rail clips. The metro vehicle-track coupling model and the fastener system refinement model were developed to analyze the effects of the material (38Si7 and 60Si2Mn) on the static and dynamic responses of the elastic rail clips and their fatigue performances under rail corrugation. According to the results, the elastic rail clip made of 60Si2Mn did not undergo any plastic deformation and exhibited higher strength than that made of 38Si7. Elastic rail clips made of 38Si7 and 60Si2Mn presented a consistent clamping force, natural frequency, and vibration acceleration. However, they were most sensitive to the wavelength of 50 mm. Both materials influenced the small back bending area of the elastic rail clip only. The elastic rail clip made of 60Si2Mn could meet the fatigue life requirements of 5 million times. As for the elastic rail clip made of 38Si7, the corresponding values of corrugation with the wavelength of 50 mm and 40 mm are to be controlled below 0.09 mm and 0.41 mm, respectively. The performance of the elastic rail clips to resist rail corrugation can be improved significantly through the increase in the geometric dimensions and selection of materials with higher strength.

scholarly journals Rail Corrugation Detection of High-Speed Railway Using Wheel Dynamic Responses

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Jianbo Li ◽  
Hongmei Shi
Keyword(s):  
High Speed ◽  
Estimation Error ◽  
Estimation Method ◽  
Dynamic Responses ◽  
Support Vector ◽  
Vibration Acceleration ◽  
High Speed Railway ◽  
Rail Corrugation ◽  
Reconstructed Signal ◽  
Wheel Vibration

Rail corrugation often occurs on the high-speed railway, which will affect ride comfort and even the train operation safety in severe condition. Detection of rail corrugation wavelength and depth is absolutely essential for maintenance and safety. A novel method using wheel vibration acceleration is proposed in this paper, in which ensemble empirical mode decomposition (EEMD) is employed to estimate the wavelength, and bispectrum features are extracted to recognize the depth with support vector machine (SVM). Firstly, a vehicle-track coupling model considering the rail corrugation of high-speed railway is established to calculate the wheel vibration acceleration. Secondly, the estimation algorithm of wavelength is studied by analyzing the main frequency with EEMD. The optimal parameters of EEMD are selected according to the orthogonal coefficient of decomposition results and the distribution of the extreme points of signal. The depth detection is transformed to a classification problem with SVM. Bispectrum features, which are extracted from the reconstructed signal using the high-frequency components of wheel vibration acceleration, combining with train speed and corrugation wavelength are input into SVM to recognize the rail corrugation depth. Finally, numerical simulation is carried out to verify the accuracy of the proposed estimation method. The simulation results show that the proposed detection algorithm can accurately identify rail corrugation, the estimation error of rail corrugation wavelength is less than 0.25%, and the classification accuracy of rail corrugation depth is more than 99%.

Numerical investigation of the fatigue performance of elastic rail clips considering rail corrugation and dynamic axle load

2020 ◽  
pp. 095440972092601
Author(s):  
Ping Wang ◽  
Jun Lu ◽  
Caiyou Zhao ◽  
Mingming Chen ◽  
Mengting Xing
Keyword(s):  
Fatigue Life ◽  
Stress Amplitude ◽  
Cyclic Stress ◽  
Maximum Speed ◽  
Analysis Method ◽  
Vibration Acceleration ◽  
Intrinsic Frequency ◽  
Rail Corrugation ◽  
Naturally Occurring ◽  
Coupling Dynamic

To analyze the reasons for rail clip fracture, the characteristics of rail corrugation were first measured using a rail corrugation meter. The vibration acceleration of the fastener clips at the sections with/without rail corrugation was measured, and the effects of rail corrugation on the clip vibration were analyzed. After this, a vehicle--track coupling dynamic model and a refined model for the fastener system were established in order to study the effects of rail corrugation on the vibration acceleration and stress on critical points. Finally, the rail grinding limits were determined based on the fatigue analysis method and the damage accumulation theory from the aspect of the fatigue life of the clip. The results of the study showed that the main wavelength of rail corrugation at the rail clip fracture section was approximately 40 mm. The vibration acceleration of the clip caused by rail corrugation was too large. Under normal installation conditions, the maximum clip stress was 1490 MPa at the small circular arc on the rear arch, which was identical to the on-site fracture location. The intrinsic frequency of the clip was approximately 810 Hz. Rail corrugation excited and triggered the forced vibration of the clip, and induced resonance at a speed of 120 km/h and a wavelength of 40 mm. The large cyclic stress amplitude of the clip with rail corrugation increased from 44 MPa to 68 MPa when compared with the clip without rail corrugation. Rail clip fracture was caused by the naturally occurring resonance fatigue arising from rail corrugation. For metro lines designed with a maximum speed of 120 km/h, it was suggested to control the rail corrugation amplitudes with a wavelength of 40 mm, 50 mm, 30 mm, 120 mm and 160 mm to below 0.04, 0.08, 0.16, 0.19 and 0.2 mm, respectively, taking into account the fatigue life of the clip.

scholarly journals Influence of turning tool wear on the surface integrity and anti-fatigue behavior of Ti1023

2021 ◽  
Vol 13 (4) ◽  
pp. 168781402110112
Author(s):  
Li Xun ◽  
Wang Ziming ◽  
Yang Shenliang ◽  
Guo Zhiyuan ◽  
Zhou Yongxin ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Plastic Deformation ◽  
Titanium Alloy ◽  
Fatigue Life ◽  
Tool Wear ◽  
Surface Integrity ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Machined Surface ◽  
Deformation Layer

Titanium alloy Ti1023 is a typical difficult-to-cut material. Tool wear is easy to occur in machining Ti1023, which has a significant negative effect on surface integrity. Turning is one of the common methods to machine Ti1023 parts and machined surface integrity has a direct influence on the fatigue life of parts. To control surface integrity and improve anti-fatigue behavior of Ti1023 parts, it has an important significance to study the influence of tool wear on the surface integrity and fatigue life of Ti1023 in turning. Therefore, the effect of tool wear on the surface roughness, microhardness, residual stress, and plastic deformation layer of Ti1023 workpieces by turning and low-cycle fatigue tests were studied. Meanwhile, the influence mechanism of surface integrity on anti-fatigue behavior also was analyzed. The experimental results show that the change of surface roughness caused by worn tools has the most influence on anti-fatigue behavior when the tool wear VB is from 0.05 to 0.25 mm. On the other hand, the plastic deformation layer on the machined surface could properly improve the anti-fatigue behavior of specimens that were proved in the experiments. However, the higher surface roughness and significant surface defects on surface machined utilizing the worn tool with VB = 0.30 mm, which leads the anti-fatigue behavior of specimens to decrease sharply. Therefore, to ensure the anti-fatigue behavior of parts, the value of turning tool wear VB must be rigorously controlled under 0.30 mm during finishing machining of titanium alloy Ti1023.

scholarly journals Research on the Dynamic Responses of Simply Supported Horizontal Pipes Conveying Gas-Liquid Two-Phase Slug Flow

Processes ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 83
Author(s):  
Gang Liu ◽  
Zongrui Hao ◽  
Yueshe Wang ◽  
Wanlong Ren
Keyword(s):  
Slug Flow ◽  
Peak Frequency ◽  
Dynamic Responses ◽  
Piping System ◽  
Transverse Displacement ◽  
Vibration Acceleration ◽  
Two Phase ◽  
Horizontal Pipes ◽  
Simply Supported ◽  
Superficial Gas Velocity

The dynamic responses of simply supported horizontal pipes conveying gas-liquid two-phase slug flow are explored. The intermittent characteristics of slug flow parameters are mainly considered to analyze the dynamic model of the piping system. The results show that the variations of the midpoint transverse displacement could vary from periodic-like motion to a kind of motion whose amplitude increases as time goes on if increasing the superficial gas velocity. Meanwhile, the dynamic responses have certain relations with the vibration acceleration. By analyzing the parameters in the power spectrum densities of vibration acceleration such as the number of predominant frequencies and the amplitude of each peak frequency, the dynamic behaviors of the piping system like periodicity could be calculated expediently.

Effect of Residual Stress or Plastic Deformation History on Fatigue Life Simulation of Pipeline Dents

2018 ◽  
Author(s):  
Xian-Kui Zhu ◽  
Rick Wang
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Fatigue Life ◽  
Residual Stresses ◽  
Three Dimensional ◽  
Strain History ◽  
Deformation History ◽  
Stress Strain ◽  
Element Analysis ◽  
Fea Model

Mechanical dents often occur in transmission pipelines, and are recognized as one of major threats to pipeline integrity because of the potential fatigue failure due to cyclic pressures. With matured in-line-inspection (ILI) technology, mechanical dents can be identified from the ILI runs. Based on ILI measured dent profiles, finite element analysis (FEA) is commonly used to simulate stresses and strains in a dent, and to predict fatigue life of the dented pipeline. However, the dent profile defined by ILI data is a purely geometric shape without residual stresses nor plastic deformation history, and is different from its actual dent that contains residual stresses/strains due to dent creation and re-rounding. As a result, the FEA results of an ILI dent may not represent those of the actual dent, and may lead to inaccurate or incorrect results. To investigate the effect of residual stress or plastic deformation history on mechanics responses and fatigue life of an actual dent, three dent models are considered in this paper: (a) a true dent with residual stresses and dent formation history, (b) a purely geometric dent having the true dent profile with all stress/strain history removed from it, and (c) a purely geometric dent having an ILI defined dent profile with all stress/strain history removed from it. Using a three-dimensional FEA model, those three dents are simulated in the elastic-plastic conditions. The FEA results showed that the two geometric dents determine significantly different stresses and strains in comparison to those in the true dent, and overpredict the fatigue life or burst pressure of the true dent. On this basis, suggestions are made on how to use the ILI data to predict the dent fatigue life.

scholarly journals Formation of microstructure and properties of Cu-3Ti alloy in thermal and thermomechanical processes

2017 ◽  
Vol 62 (1) ◽  
pp. 223-230 ◽  
Author(s):  
A. Szkliniarz
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Plastic Deformation ◽  
Cold Working ◽  
Cold Deformation ◽  
Solution Treatment ◽  
Cold Plastic Deformation ◽  
Working Solution ◽  
Thermomechanical Processes ◽  
Selection Of

Abstract This paper presents the possibilities of forming the microstructure as well as mechanical properties and electrical conductivity of Cu-3Ti alloy (wt.%) in thermal and thermomechanical processes that are a combination of homogenising treatment, hot and cold working, solution treatment and ageing. Phase composition of the alloy following various stages of processing it into the specified semi-finished product was being determined too. It was demonstrated that the application of cold plastic deformation between solution treatment and ageing could significantly enhance the effect of hardening of the Cu-3Ti alloy without deteriorating its electrical conductivity. It was found that for the investigated alloy the selection of appropriate conditions for homogenising treatment, hot and cold deformation as well as solution treatment and ageing enables to obtain the properties comparable to those of beryllium bronzes.

The Effect of Several Finishing Processes on the Fatigue Resistance of Hole Surfaces

1989 ◽  
Vol 111 (1) ◽  
pp. 71-73 ◽  
Author(s):  
M. O. Lai ◽  
A. Y. C. Nee
Keyword(s):  
Surface Roughness ◽  
Plastic Deformation ◽  
Fatigue Life ◽  
Residual Stresses ◽  
Fatigue Resistance ◽  
Radial Direction ◽  
Fatigue Loading ◽  
Steel Plates ◽  
Finishing Processes ◽  
Compressive Residual Stresses

This investigation examines the effects of different finishing processes on the fatigue life of premachined holes in Assab 760 steel plates. The finishing processes studied were reaming, ballizing, and emery polishing. A general decrease in fatigue life with increase in surface roughness is observed for all the processes employed. In comparing the different processes, for a constant surface roughness, polishing is generally found to give the longest fatigue life while ballizing, in spite of the greater compressive residual stresses induced on the surface of the finished hole, the shortest. The surprising phenomenon was found to be attributed to the amount of plastic deformation occurred before fatigue loading. For Assab 760 steel, a prestrain in the radial direction of less than about 2.5 percent appeared to reduce the fatigue resistance of the material.

Estimation of Track Irregularity Based on Genetic Algorithm and Unscented Kalman Filtering

2012 ◽  
Author(s):  
Hongmei Shi ◽  
Zujun Yu
Keyword(s):  
Genetic Algorithm ◽  
Kalman Filtering ◽  
High Speed ◽  
Measurement Data ◽  
Estimation Method ◽  
Coupling Model ◽  
Dynamic Responses ◽  
The Real ◽  
True Value ◽  
Track Irregularity

Track irregularity is the main excitation source of wheel-track interaction. Due to the difference of speed, axle load and suspension parameters between track inspection train and the operating trains, the data acquired from the inspection car cannot completely reflect the real status of track irregularity when the operating trains go through the rail. In this paper, an estimation method of track irregularity is proposed using genetic algorithm and Unscented Kalman Filtering. Firstly, a vehicle-track vertical coupling model is established, in which the high-speed vehicle is assumed as a rigid body with two layers of spring and damping system and the track is viewed as an elastic system with three layers. Then, the static track irregularity is estimated by genetic algorithm using the vibration data of vehicle and dynamic track irregularity which are acquired from the inspection car. And the dynamic responses of vehicle and track can be solved if the static track irregularity is known. So combining with vehicle track coupling model of different operating train, the potential dynamic track irregularity is solved by simulation, which the operating train could goes through. To get a better estimation result, Unscented Kalman Filtering (UKF) algorithm is employed to optimize the dynamic responses of rail using measurement data of vehicle vibration. The simulation results show that the estimated static track irregularity and the vibration responses of vehicle track system can go well with the true value. It can be realized to estimate the real rail status when different trains go through the rail by this method.

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