scholarly journals Formation Mechanism of Metro Rail Corrugation Based on Wheel–Rail Stick–Slip Behaviors

2021 ◽  
Vol 11 (17) ◽  
pp. 8128
Author(s):  
Zhiqiang Wang ◽  
Zhenyu Lei
Keyword(s):  
Formation Mechanism ◽  
Coupling Model ◽  
Field Investigation ◽  
Small Radius ◽  
Large Radius ◽  
Stick Slip ◽  
Flexible Coupling ◽  
Rail Corrugation ◽  
Curve Track ◽  
The Relationship

Field investigation shows that most corrugations occur on the inner rail surface of curved tracks with a radius of less than 700 m. In order to explore the formation mechanism of metro corrugation, the relationship between wheel–rail stick–slip characteristics and rail corrugation is studied by combining single wheelset curving and a rigid–flexible coupling model. The numerical results illustrate that the lateral torsional stick–slip vibration of inner rail–inner wheel of the guiding wheelset on the small radius curve eventually leads to the generation of inner rail corrugation, and the lateral torsional stick–slip vibration of outer rail–outer wheel of the driven wheelset may also occur, but the intensity is weak and the probability is low. The lateral torsional stick–slip vibration of inner rail–inner wheel of the guiding wheelset on the large radius curve is also easy to cause inner rail corrugation, but the degree of inner rail corrugation is lower than that on the small radius curve; the outer rail on the large radius curve is still not easy to produce corrugation. The formation mechanism of rail corrugation on the straight track is different from that on the curve track, which is mainly related to the wheel–rail longitudinal torsional stick–slip vibration.

scholarly journals Field Investigation and Rapid Deterioration Analysis of Heavy Haul Corrugation

2021 ◽  
Vol 11 (14) ◽  
pp. 6317
Author(s):  
Feng Jin ◽  
Hong Xiao ◽  
Mahantesh M Nadakatti ◽  
Huiting Yue ◽  
Wanting Liu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fatigue Cracks ◽  
Field Measurements ◽  
Field Investigation ◽  
The Finite Element Method ◽  
Rail Corrugation ◽  
Rapid Deterioration ◽  
Heavy Haul

In this study, the rapid growth of corrugation caused by the bad quality of grinding works and their wavelength, depth, and evolution processes are captured through field measurements. The residual grinding marks left by poor grinding quality lead to further crack accumulation and corrugation deterioration by decreasing plastic resistance in rails. In this case, the average peak-to-peak values of corrugation grow extremely fast, reaching 1.4 μm per day. The finite element method (FEM) and fracture mechanics methodologies were used to analyze the development and trends in rail surface crack deterioration by considering rails with and without grinding marks. Crack propagation trends increase with residual grinding marks, and they are more severe in circular curve lines. To avoid the rapid deterioration of rail corrugation, intersections between grinding marks and fatigue cracks should be avoided.

Coexistence of large-radius and small-radius polaron states in a quantum wire

1995 ◽  
Vol 17 (11-12) ◽  
pp. 1723-1728
Author(s):  
Y. Shinozuka ◽  
N. Ishida
Keyword(s):  
Quantum Wire ◽  
Small Radius ◽  
Large Radius

Dynamic Characteristic Analysis of Irregularity under Turnout by Vehicle-Turnout Rigid-Flexible Coupling Model

2014 ◽  
Vol 945-949 ◽  
pp. 591-595 ◽  
Author(s):  
Meng Chen ◽  
Yan Yun Luo ◽  
Bin Zhang
Keyword(s):  
Finite Element ◽  
Longitudinal Direction ◽  
Element Model ◽  
Vertical Displacement ◽  
Coupling Model ◽  
Interaction Force ◽  
Vertical Acceleration ◽  
Characteristic Analysis ◽  
Flexible Coupling ◽  
Multi Body

Finite element model of track in frog zone is built by vehicle-turnout system dynamics. Considering variation of rail section and elastic support, bending deformation of turnout sleeper, spacer block and sharing pad effects, the track integral rigidity distribution in longitudinal direction is calculated in the model. Vehicle-turnout rigid-flexible coupling model is built by finite element method (FEM), multi-body system (MBS) dynamics and Hertz contact theory. With the regularity solution that different stiffness is applied for rubber pad under sharing pad of different turnout sleeper zone, analysis the variation of vertical acceleration of bogie and wheelset, rail vertical displacement and wheel-rail interaction force, this paper proves that setting reasonable rubber pad stiffness is an efficient method to solve rigidity irregularity problem.

New Understandings of the Relationship and Initial Formation Mechanism for Pseudo-lignin, Humins, and Acid-Induced Hydrothermal Carbon

2018 ◽  
Vol 66 (45) ◽  
pp. 11981-11989 ◽  
Author(s):  
Banggui Cheng ◽  
Xiaohui Wang ◽  
Qixuan Lin ◽  
Xiao Zhang ◽  
Ling Meng ◽  
...  
Keyword(s):  
Formation Mechanism ◽  
Initial Formation ◽  
The Relationship

scholarly journals Triple Oxygen Isotope Measurements by Multi-Collector Secondary Ion Mass Spectrometry

2021 ◽  
Vol 8 ◽  
Author(s):  
Nordine Bouden ◽  
Johan Villeneuve ◽  
Yves Marrocchi ◽  
Etienne Deloule ◽  
Evelyn Füri ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Oxygen Isotope ◽  
Spatial Resolution ◽  
Secondary Ion Mass Spectrometry ◽  
Small Radius ◽  
Large Radius ◽  
Ion Mass Spectrometry ◽  
Secondary Ion ◽  
Isotope Measurements

Secondary ion mass spectrometry (SIMS) is a powerful technique for in situ triple oxygen isotope measurements that has been used for more than 30 years. Since pioneering works performed on small-radius ion microprobes in the mid-80s, tremendous progress has been made in terms of analytical precision, spatial resolution and analysis duration. In this respect, the emergence in the mid-90s of the large-radius ion microprobe equipped with a multi-collector system (MC-SIMS) was a game changer. Further developments achieved on CAMECA MC-SIMS since then (e.g., stability of the electronics, enhanced transmission of secondary ions, automatic centering of the secondary ion beam, enhanced control of the magnetic field, 1012Ω resistor for the Faraday cup amplifiers) allow nowadays to routinely measure oxygen isotopic ratios (18O/16O and 17O/16O) in various matrices with a precision (internal error and reproducibility) better than 0.5‰ (2σ), a spatial resolution smaller than 10 µm and in a few minutes per analysis. This paper focuses on the application of the MC-SIMS technique to the in situ monitoring of mass-independent triple oxygen isotope variations.

scholarly journals Analysis of influence factors of rail corrugation in small radius curve track

2021 ◽  
Vol 12 (1) ◽  
pp. 31-40
Author(s):  
Zhiqiang Wang ◽  
Zhenyu Lei
Keyword(s):  
Influence Factors ◽  
Small Radius ◽  
Track Structure ◽  
Complex Eigenvalue ◽  
Three Dimensional Model ◽  
Rail Corrugation ◽  
Finite Element Software ◽  
Rail System ◽  
Side Rail ◽  
Excited Vibration

Abstract. In order to effectively prevent and control the generation and development of rail corrugation, according to the actual line condition of the small radius curve section, the vehicle (with flexible wheel sets)–track space coupled model was established by using the multi-body dynamic software UM (Universal Mechanism), which could consider the coupled relationship in three directions of space, and the dynamic analysis for the corrugation section was carried out by using the model. Then, based on the theory of friction self-excited vibration, the three-dimensional model of a wheel–rail system was established by using the finite-element software ABAQUS, and the complex eigenvalue analysis of influence factors of rail corrugation was conducted based on wheel–rail contact parameters obtained by dynamic calculation. Through the stability analysis of the wheel–rail system with different fastener vertical and lateral stiffnesses, friction coefficients, and superelevation states, we find that properly increasing the fastener vertical and lateral stiffnesses, controlling the wheel–rail friction coefficient below 0.4, and keeping the balanced superelevation state of the track structure can effectively reduce the occurrence possibility of unstable vibration of the wheel–rail system, thus inhibiting the generation and development of rail corrugation. The excess superelevation state of the track structure results in the unstable friction self-excited vibration of the wheel–rail system at the inner wheel–inner rail, while the deficient superelevation state results in the unstable friction self-excited vibration of the wheel–rail system at the outer wheel–outer rail, which shows that the superelevation state of the track structure directly affects the formation of rail corrugation and determines the development order of corrugation of inner and outer rails. This conclusion can well explain the cause of corrugation appearing on only one side rail.

scholarly journals The President’s Influence on the Formation of Lithuanian Foreign Policy: A Shift of the Power Center During Grybauskaitė’s Term

Politologija ◽  
2019 ◽  
Vol 94 (2) ◽  
pp. 8-55
Author(s):  
Tomas Janeliūnas
Keyword(s):  
Foreign Policy ◽  
Formation Mechanism ◽  
Policy Making ◽  
Policy Formation ◽  
Foreign Affairs ◽  
Power Center ◽  
And Behavior ◽  
The Relationship

This article raises the question of what role does the presidential institution hold in the Lithuanian foreign policy formation mechanism and how a particular actor (president) can change their powers in foreign policy without going beyond the functions formally defined in the Constitution. The period of President Grybauskaitė’s term and her efforts as an actor to define her role in shaping Lithuanian foreign policy are analyzed. This is assessed in the context of the activities and behavior of former Lithuanian presidents and in the context of relations with other institutions involved in foreign policy making – the Ministry of Foreign Affairs (MFA) and the Seimas in particular. This article analyzes the relationship between the actor (Grybauskaitė) and the already established structure of domestic foreign policy formation and the ability of the actor to change this structure. The analysis suggests that it is precisely because of the choices made by Grybauskaite during 2009–2019 that a relationship between the structures of foreign policy making in Lithuania has changed considerably, and that the center of power of foreign policy formation has shifted to the presidency.

scholarly journals Layout design of new production shop based on SLP

2021 ◽  
Vol 251 ◽  
pp. 03097
Author(s):  
Lijie Zhao
Keyword(s):  
Material Handling ◽  
Field Investigation ◽  
Production Costs ◽  
General Situation ◽  
New Production ◽  
Systematic Layout Planning ◽  
Operation Unit ◽  
Work Units ◽  
The Cost ◽  
The Relationship

It has become the main way for heavy industry enterprises to decrease the cost to excavate “logistics resources” according to the Systematic Layout Planning (SLP). Taking the new tool shaft machining workshop of Luoyang yituo zhongcheng machinery co., LTD. as an example, through the method of field investigation and visit, we get the data of the process flow, material handling, the relationship between each process and the general situation of the new workshop. The SLP method is used to divide the work units in the workshop, analyze the relationship between logistics and non-logistics among each work unit, determine the comprehensive relationship between each operation unit, and make the position correlation diagram. Besides, we also combine the current situation of the workshop to sort out the layout scheme to reduce the production costs of the workshop.

Theoretical investigation into the formation mechanism and mitigation measures of short pitch rail corrugation in resilient tracks of metros

2018 ◽  
Vol 232 (9) ◽  
pp. 2260-2271 ◽  
Author(s):  
Ge Fang ◽  
Yurong Wang ◽  
Zhike Peng ◽  
Tianxing Wu
Keyword(s):  
Formation Mechanism ◽  
Wave Reflection ◽  
Interaction Model ◽  
Mitigation Measures ◽  
Rail Corrugation ◽  
Characteristic Wavelength ◽  
Dynamic Forces ◽  
Low Stiffness ◽  
Shanghai Metro ◽  
Good Agreement

Severe rail corrugation occurs at both the curved and tangent tracks of the metro in Shanghai, where resilient rail fasteners are used to reduce ground-borne vibration by isolating the transmission of track vibration to the infrastructure. The wavelength of corrugation is about 25–30 mm. It could be assumed that this short pitch rail corrugation is caused by the pinned–pinned resonance. However, rail fasteners with low stiffness were believed to be able to suppress the pinned–pinned resonance thereby resulting in corrugation. To investigate the formation mechanism of this specific rail corrugation, a multiple wheel–rail interaction model is used to calculate the wheel–rail dynamic forces caused due to the multiple wheel–rail interactions, which are considered to play a major role in the formation of corrugation. Then the influences on wear and corrugation growth are analyzed in terms of both amplitude and phase of the wheel–rail dynamic forces. By combining the properties of multiple wheel–rail interactions with their influences on wear and corrugation, the growth rates of rail corrugation at different wavelengths (frequencies) are studied to obtain the characteristic wavelength (frequency), at which the highest corrugation growth rate appears. The obtained characteristic wavelength is in good agreement with observation in the practice of Shanghai metro. It is found that the wave reflection from the wheels on the rail is responsible for the short pitch rail corrugation in the resilient tracks. Finally, tuned rail dampers are applied in the multiple wheel–rail interaction models to investigate their effects on rail corrugation growth. The simulation results show that use of tuned rail dampers is effective in suppressing the short pitch rail corrugation occurring at resilient tracks.

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