Analysis on Impact Loading at Rail Welds at High Speed

2008 ◽  
Author(s):  
Guangwen Xiao ◽  
Xinbiao Xiao ◽  
Zefeng Wen ◽  
Xuesong Jin
Keyword(s):  
Impact Loading ◽  
High Speed ◽  
Hertzian Contact ◽  
Railway Vehicle ◽  
Vehicle Speed ◽  
Explicit Integration ◽  
Normal Forces ◽  
Rail Irregularity ◽  
Multi Body ◽  
The Impact

When a railway vehicle passes through a track with different weld irregularities at high speed, the impact loading of the vehicle coupled with the track is investigated in detail using a coupled vehicle/track model. In this model, a half vehicle is considered and modeled as a multi-body system. In the track model, a Timoshenko beam resting on discrete sleepers is applied to model each rail. Each sleeper is modeled as a rigid body accounting for its vertical, lateral, roll motions. A moving sleeper support model is used to simulate the interaction of the vehicle and the track. The ballast bed is replaced with equivalent masses. The equivalent dampers and springs are used to replace the connections between the parts of the vehicle and track. In calculating the coupled vehicle and track dynamics, Hertzian contact theory and the creep force theory by Shen et al. are, respectively, used to calculate the normal forces and the creep forces between the wheels and the rails. The motion equations of the vehicle-track are solved by means of an explicit integration method. The weld rail irregularity is modeled by setting a local track vertical deviation at a rail weld joint, which is described with a simplified cosine function. In the numerical analysis the effect of the different wavelength, depth, the position of the welded joint in a sleeper span, and vehicle speed is taken into account. The numerical results obtained are greatly useful in the tolerance design of welded rail profile irregularity caused by damage and hand-grinding after rail welding.

Dynamic Analysis of Pitch Plane Railway Vehicle-Track Interactions Due to Single and Multiple Wheel Flats

2008 ◽  
Author(s):  
Rajib Ul Alam Uzzal ◽  
Subhash Rakheja ◽  
Waiz Ahmed
Keyword(s):  
Parametric Study ◽  
High Speed ◽  
Impact Load ◽  
Critical Length ◽  
Hertzian Contact ◽  
Railway Vehicle ◽  
Main Concern ◽  
Track System ◽  
Wheel Flat ◽  
The Impact

The dynamic impact forces due to the wheel defect such as a flat is a main concern for a heavy freight train operating at high speed. The present investigation employs a pitch plane vehicle model coupled with a comprehensive three-layer track system model to study the impact force generated in the wheel-rail interface due to the presence of wheel flats. The wheel-rail contact is modeled using nonlinear Hertzian contact theory. Responses in terms of wheel-rail impact load and forces transmitted to bearings, pad and ballast are evaluated in an attempt to identify desirable design and operating factors. Wheel-rail impact loads due to the presence of multiple flats either in single or different wheels in-phase or out-of-phase conditions are evaluated and analyzed. A detailed parametric study is carried out that includes the variations in selected vehicle, track, operational as well as flat parameters. The results show that the effect of multiple flats is insignificant if they are more than 45° apart. The impact due to single wheel flat can be larger than in-phase flats at each wheel due to the presence of pitch dynamics. The parametric study shows that other than speed, depth and length of the flats are most sensitive parameters, and there exists a critical length at each flat depth that leads to the largest impact load.

Study on Derailment Mechanism and Safety Operation Area of High-Speed Trains Under Earthquake

2012 ◽  
Vol 7 (4) ◽  
Author(s):  
Liang Ling ◽  
Xinbiao Xiao ◽  
Xuesong Jin
Keyword(s):  
High Speed ◽  
Dynamical Behavior ◽  
Vehicle Speed ◽  
Vertical Force ◽  
Explicit Integration ◽  
Running Safety ◽  
Earthquake Motion ◽  
High Speed Trains ◽  
Wheel Loading ◽  
Safety Operation

In order to investigate the derailment mechanism and safety operation area of high-speed trains under earthquake, a coupled vehicle-track dynamic model considering earthquake effect is developed, in which the vehicle is modeled as a 35 degrees of freedom (DOF) multibody system with nonlinear suspension characteristic and the slab track is modeled as a discrete elastic support model. The rails of the track are assumed to be Timoshenko beams supported by discrete rail fasteners, and the slabs are modeled with solid finite elements. The system motion equations are solved by means of an explicit integration method in time domain. The present work analyzes in detail the effect of earthquake characteristics on the dynamical behaviors of a vehicle-track coupling system and the transient derailment criteria. The considered derailment criteria include the ratio of the wheel/rail lateral force to the vertical force, the wheel loading reduction, the wheel/rail contact point traces on the wheel tread, and the wheel rise with respect to the rail top, respectively. The present work also finds the safety operation area, the derailment area, and the warning area of high-speed trains under earthquake, and their boundaries. These areas consist of three key parameters influencing the dynamical behavior of high-speed train and track under earthquake. The three key influencing parameters are, respectively, the vehicle speed and the lateral and vertical peak ground acceleration (PGA) of an earthquake. The results obtained indicate that the lateral earthquake motion has a greater influence on the vehicle dynamic behavior and its running safety compared to the vertical earthquake motion. The risk of derailment increases quickly with the increasing of lateral earthquake motion amplitude. The lateral earthquake motion is dominant in the vehicle running safety influenced by an earthquake. While the vertical earthquake motion promotes jumping of the wheels easily, not easy is flange climb derailment. And the effect of the vehicle speed is not significant under earthquake.

Derailment Analysis of High-Speed Railway Vehicle Bogies

2011 ◽  
Vol 110-116 ◽  
pp. 186-195 ◽  
Author(s):  
Yung Chang Cheng ◽  
Chern Hwa Chen ◽  
Che Jung Yang
Keyword(s):  
High Speed ◽  
Lateral Displacement ◽  
Vertical Displacement ◽  
Creep Model ◽  
Railway Vehicle ◽  
Vehicle Speed ◽  
Nonlinear Creep ◽  
Bogie Frame ◽  
Suspension Parameters ◽  
Yaw Angle

Based on the heuristic nonlinear creep model, the nonlinear coupled differential equations of the motion of a 12 degree-of-freedom (12-DOF) bogie system which takes account of the lateral displacement, vertical displacement, the roll angle and the yaw angle of the each wheelset and the bogie frame, moving on curved tracks are derived. The nonlinear creep forces and moments are constructed via the saturation constant of the nonlinear creep model in completeness. The effect of the suspension parameters of a bogie system on the derailment quotient is investigated. Results obtained in this study show that the derailment quotient of a bogie system increases as the vehicle speed increases. In addition, the derailment quotient of a bogie system is generally decreased with the increasing values of suspension parameters.

scholarly journals Flexible-Rigid Wheelset Introduced Dynamic Effects due to Wheel Tread Flat

2021 ◽  
Vol 2021 ◽  
pp. 1-21
Author(s):  
Awel Momhur ◽  
Y. X. Zhao ◽  
Liwen Quan ◽  
Sun Yazhou ◽  
Xialong Zou
Keyword(s):  
High Speed ◽  
Statistical Approach ◽  
Impact Load ◽  
Vertical Acceleration ◽  
Vehicle Speed ◽  
Dynamic Impact ◽  
Element Analysis ◽  
Wheel Flat ◽  
Wheel Radius ◽  
The Impact

The widespread faults that occur in railway wheels and can cause a massive dynamic impact are the wheel tread flat. The current work considered changes in vehicle speed or wheel radius deviation and studied the dynamic impact load. The modal technique for the impact evaluation induced by the wheel flat was proposed via the finite element analysis (FEA) software package ANSYS, integrated into a multibody dynamics model of the high-speed train CRH2A (EMU) through SIMPACK. The irregularity track line has developed and depends on the selected simulation data points. Additionally, a statistical approach is designed to analyze the dynamic impact load response and effect and consider different wheel flat lengths and vehicle speeds. The train speed influence on the flat size of the vertical wheel-rail impact response and the statistical approach are discussed based on flexible, rigid wheelsets. The results show that the rigid wheel flat has the highest vertical wheel impact load and is more significant than the flexible wheel flat force. The consequences suggest that the wheelset flexibility can significantly improve vertical acceleration comparably to the rigid wheel flats. In addition, the rendering of the statistical approach shows that the hazard rate, PDF, and CDF influence increase when the flat wheel length increases.

Reinvestigation into railway wheel-track interaction and suspension damage

2020 ◽  
pp. 095440972093202
Author(s):  
Renfan Luo ◽  
David Vincent
Keyword(s):  
High Speed ◽  
Sensitivity Study ◽  
Hertzian Contact ◽  
Contact Theory ◽  
Fe Model ◽  
Fe Modelling ◽  
Wheel Flat ◽  
The Impact ◽  
Hertzian Contact Theory ◽  
Wheel Track

Without considering either velocity or acceleration effects, the current conventional method presented in literature applies the vertical deflection of a wheel centre caused by a flat defect to the Hertzian contact theory. This method has been numerically and theoretically proved to be inappropriate and can incorrectly predict a higher wheel-rail impact force for a low speed than a high speed. Therefore, under a hypothesis of no wheel bouncing and sliding, two new methods, the velocity-based and the acceleration-based have been proposed. The former method takes the wheel centre deflection change in each computational increment from the Hertzian contact theory while the latter applies the wheel centre acceleration caused by the flat in revolutions to the wheel as a force in dynamic simulation, which interprets the speed effects on impacts precisely. A sensitivity study proves that the velocity-based method is unreliable as opposed to the acceleration-based method. A beam/rigid FE model has also been developed to inspect the wheel-track interaction by performing dynamic analysis in the time domain. It has been found out that the impact responses predicted by the FE analysis and the velocity method are similar and the FE results heavily depend on the compute increment, which implies the FE modelling in ABAQUS may be unreliable for this issue with current applied increments. Finally, the results calculated using the acceleration method have been employed to study the suspension/damper torsional stress caused by a wheel flat. This indicates that a wheel flat may lead to potential fatigue damage if without proper maintenance management.

Dynamic Analysis for Derailment Safety of High-Speed Railway Vehicle Bogies

2011 ◽  
Vol 199-200 ◽  
pp. 239-242
Author(s):  
Chern Hwa Chen ◽  
Yung Chang Cheng ◽  
Shun Chin Yang ◽  
Yuh Yi Lin ◽  
Cheng Hsin Chang ◽  
...  
Keyword(s):  
High Speed ◽  
Lateral Displacement ◽  
Vertical Displacement ◽  
Creep Model ◽  
Railway Vehicle ◽  
Vehicle Speed ◽  
Nonlinear Creep ◽  
Suspension Parameters ◽  
Derailment Safety ◽  
Yaw Angle

Based on the heuristic nonlinear creep model, the nonlinear coupled differential equations of the motion of a 12 degree-of-freedom (12-DOF) bogie system which takes account of the lateral displacement, vertical displacement, the roll angle and the yaw angle of the each wheelset and the bogie frame, moving on curved tracks are derived. The nonlinear creep forces and moments are constructed via the saturation constant of the nonlinear creep model in completeness. The effect of the suspension parameters of a bogie system on the derailment quotient is investigated. Results obtained in this study show that the derailment quotient of a bogie system increases as the vehicle speed increases. In addition, the derailment quotient of a bogie system is generally decreased with the increasing values of suspension parameters.

Multi-Body Impact Motion With Friction: Analysis, Simulation, and Experimental Validation

1990 ◽  
Author(s):  
Inhwan Han ◽  
B. J. Gilmore
Keyword(s):  
High Speed ◽  
Video Camera ◽  
Impact Dynamics ◽  
Body System ◽  
High Speed Video Camera ◽  
Multi Body ◽  
The Impact ◽  
Friction Analysis ◽  
Impact Motion

Abstract When a multi-body system collides with a single body or with another multi-body system, impact dynamics with friction should be considered. This paper presents a general computer oriented analysis of impact dynamics incorporating friction. The presence of friction between sliding contacts during the impact makes the problem difficult since the events such as reverse sliding or sticking, which may occur at different times throughout the impact, must be determined. The boundary representations of the bodies are used to solve for the velocities at the points of contact. Using this information and a classification of the modes of impact, the frictional impact with sliding contact problem is solved. Using a high speed video camera, the resulting computer strategy is experimentally verified. Simulation and experimental results agree.

Development of the Analysis Model for Overhead Contact Line and Pantograph by EN Standard

2011 ◽  
Author(s):  
Jin-Hee Lee ◽  
Tae-Won Park ◽  
Sung-Pil Jung
Keyword(s):  
Contact Line ◽  
High Speed ◽  
Simulation Method ◽  
Railway Vehicle ◽  
Vehicle Speed ◽  
Analysis Model ◽  
Beam Elements ◽  
Sliding Joint ◽  
Multibody Dynamic ◽  
Catenary System

The evaluation of the contact loss of the catenary system is the highlight issue for the high-speed railway vehicle. In this paper, using the multibody dynamic analysis techniques including a flexible body, the simulation method of the catenary system is proposed. The pantograph and overhead contact line are developed by using rigid body and ANCF (Absolute Nodal Coordinate Formulation) beam elements, respectively. And relative motions are constrained by sliding joint. Using this analysis model, contact force and loss of contact are calculated according to vehicle speed. The results of the simulation are evaluated by EN 50318 that is the international standard with regard to validation of the dynamic interaction between pantograph and overhead contact line.

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