Study of Train Derailments Caused by Damage to Suspension Systems

2015 ◽  
Vol 11 (3) ◽  
Author(s):  
S. H. Ju
Keyword(s):  
Finite Element ◽  
Nonlinear Finite Element Method ◽  
Train Derailment ◽  
Interval Time ◽  
Suspension Systems ◽  
Derailment Coefficient ◽  
Parametric Studies ◽  
Train Speed ◽  
Rail Irregularities ◽  
Secondary Suspension

A nonlinear finite element method was used to investigate the derailments of trains moving on multispan simply supported bridges due to damage to suspension systems. At the simulation beginning, the initial vertical trainloads to simulate the train gravity weight are gradually added into the mass center of each rigid body in the train model with large system damping, so the initial fake vibration is well reduced. A suspension is then set to damage within the damage interval time, while the spring and/or damper changes from no damage to a given percentage of damage. Finite element parametric studies indicate the following: (1) the derailment coefficients of the wheel axis nearby the damage location are significantly increased. (2) Damage to the spring is more critical than that to the damper for the train derailment effect. (3) The derailment coefficient induced by damage to the primary suspension is more serious than that to the secondary suspension. (4) If rail irregularities are neglected, the train speed has little influence on the derailment coefficients generated from damage to suspensions. (5) The train derailment coefficients rise with a decrease in the damage interval time, so sudden damages to suspension systems should be avoided.

Simulation of Train Derailment in Passing Over Rails With Random Irregularities on a Viscoelastic Foundation

2008 ◽  
Author(s):  
Mohammad Durali ◽  
Mohammad Mahdi Jalili
Keyword(s):  
Degrees Of Freedom ◽  
Viscoelastic Foundation ◽  
Train Derailment ◽  
Suspension Systems ◽  
Derailment Coefficient ◽  
Center Pivot ◽  
Non Linear ◽  
Linear Elements ◽  
Secondary Suspension ◽  
New Criterion

Derailment of a passenger wagon on a rail with random irregularities is investigated in this paper. The wagon having 48 degrees of freedom is assumed to travel over a rail on a viscoelastic foundation. The wagon model is a 3-D, non-linear model of a passenger train car, considering non-linear elements for the primary and secondary suspension systems having friction and slack between their elements, the center pivot with kinematics constraints, forces between pads, and bolster. The motion of the wagon on rail with random vertical irregularities is simulated for different line grades and travel speeds. Derailment coefficient and a new derailment criterion are used to investigate probability of wheelset derailment moving on different line grades. The study shows that the new criterion can very well predict wheelset derailment and can duplicate the predictions by conventional derailment coefficient (Q/P). Comparison of the wagon derailment on lines with different sleeper rigidity shows that increase in sleeper rigidity decrease derailment probability.

Investigation on Train Derailment Using a New Criterion

2009 ◽  
Author(s):  
Mohammad Durali ◽  
Mohammad Mahdi Jalili
Keyword(s):  
Dynamic Parameters ◽  
Train Derailment ◽  
Suspension Systems ◽  
Derailment Coefficient ◽  
Center Pivot ◽  
Non Linear ◽  
Linear Elements ◽  
Secondary Suspension ◽  
Definition Of ◽  
New Criterion

A new criterion for prediction of train derailment is presented in this paper. A 2 DOF wheel-set model is used to identify the main dynamic parameters that affect wheel-set derailment. Using these parameters and conventional definition of derailment coefficient, a new criterion for prediction of wheelset derailment is introduced. The proposed criterion, in addition to providing the required precision in prediction of wheelset derailment, it requires measurements which are easy to perform. To evaluate the capability of the new criterion in prediction of derailment, a full wagon model with 48 DOF was used. The wagon model is a 3-D, non-linear model of a train passenger car. The model includes non-linear elements for primary and secondary suspension systems. Friction and slack between elements, the center pivot with kinematics constraints, forces between pads, and bolster are also included in this model. The motion of the wagon on curved tracks is simulated for different travel speeds. Derailment coefficient and a new derailment criterion are used to investigate possibility of wheelset derailment in each case. The study shows that the new criterion can very well predict wheelset derailment and can duplicate the predictions by conventional derailment coefficient (Y / Q).

scholarly journals Running Safety of Trains under Vessel-Bridge Collision

2015 ◽  
Vol 2015 ◽  
pp. 1-11
Author(s):  
Yongle Li ◽  
Jiangtao Deng ◽  
Bin Wang ◽  
Chuanjin Yu
Keyword(s):  
Element Model ◽  
Dynamic Responses ◽  
Lateral Acceleration ◽  
Vertical Acceleration ◽  
Running Safety ◽  
Derailment Coefficient ◽  
Parametric Studies ◽  
Train Speed ◽  
Unloading Rate ◽  
Bridge System

To optimize the sensor placement of the health monitoring system, the dynamic behavior of the train-bridge system subjected to vessel-collision should be studied in detail firstly. This study thus focuses on the characteristics of a train-bridge system under vessel-bridge collision. The process of the vessel-bridge collision is simulated numerically with a reliable finite element model (FEM). The dynamic responses of a single car and a train crossing a cable-stayed bridge are calculated. It is shown that the collision causes significant increase of the train’s lateral acceleration, lateral wheelset force, wheel unloading rate, and derailment coefficient. The effect of the collision on the train’s vertical acceleration is much smaller. In addition, parametric studies with various train’s positions, ship tonnage, and train speed are performed. If the train is closer to the vessel-bridge collision position or the ship tonnage is larger, the train will be more dangerous. There is a relatively high probability of running danger at a low speed, resulting from longer stay of the train on the bridge. The train’s position, the ship tonnage, and the train speed must be considered when determining the most adverse conditions for the trains running on bridges under vessel-bridge collision.

LATERAL BUCKLING OF THE STRUTS IN BEAM STRING STRUCTURES CONSIDERING THE LAYOUT OF STRINGS

2012 ◽  
Vol 12 (03) ◽  
pp. 1250015 ◽  
Author(s):  
MINGER WU ◽  
KENICHI HIRAI
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Nonlinear Finite Element ◽  
Lateral Stiffness ◽  
Geometrically Nonlinear ◽  
Nonlinear Finite Element Method ◽  
Rotational Stiffness ◽  
Lateral Buckling ◽  
String Structure ◽  
Parametric Studies

The struts in a beam string structure (BSS) may buckle laterally under compression. The lateral buckling of the struts is determined not only by the rotational stiffness of the beam–strut joints and the length and bending stiffness of the struts, but also by the rise and lateral stiffness of the beam, the number of struts, and the layout of strings. In this paper, the multi-strut BSS with several types of layout of strings is studied. An analytical method for estimating the lateral buckling load of the struts in BSS is proposed. Parametric studies are carried out to investigate the variation of the lateral buckling of the struts in the BSS for different string layouts. In the end, the validity of the proposed method is examined by means of numerical simulations using the geometrically nonlinear finite element method.

Ride Quality of High-Speed Trains Traveling Over the Corrugated Rails

2006 ◽  
Author(s):  
H. Farahpour ◽  
D. Younesian ◽  
E. Esmailzadeh
Keyword(s):  
High Speed ◽  
Ride Comfort ◽  
The Body ◽  
Ride Quality ◽  
Comfort Index ◽  
Suspension Systems ◽  
Power Spectral ◽  
High Speed Trains ◽  
Train Speed ◽  
Secondary Suspension

Ride comfort of high-speed trains is studied using Sperling's comfort index. Dynamic model is developed in the frequency domain and the power spectral density (PSD) of the body acceleration is obtained for four classes of tracks. The obtained acceleration PSD is then filtered using Sperling's filter. The effects of the rail roughness and train speed on the comfort indicators are investigated. A parametric study is also carried out to evaluate the effects of the primary and secondary suspension systems on the comfort indicators.

scholarly journals Investigation of vibration induced by moving cranes in high-tech factories

2019 ◽  
Vol 39 (1) ◽  
pp. 84-97 ◽  
Author(s):  
SH Ju ◽  
HH Kuo ◽  
SW Yu ◽  
SH Ni
Keyword(s):  
Finite Element ◽  
Natural Frequencies ◽  
Element Model ◽  
High Tech ◽  
Beam Depth ◽  
Parametric Studies ◽  
Plate Spring ◽  
Beam Center ◽  
Rail Irregularities ◽  
Good Agreement

A finite element model was developed to simulate the crane induced vibration on the floor of high-tech factories, in which the mesh include beam, plate, spring-damper, and moving wheel elements. The finite element results were first compared with the experimental measurements in good agreement. The parametric studies were then performed to study the vibration behavior of high-tech factories due to the effects of rail irregularities, slab depth, and crane speed. The rail irregularities induce the vibration of the crane and slab at their natural frequencies, and both rail irregularities and the crane acceleration induce the crane rotation in its natural frequency, so that smoothing the wheel and rail should be the first priority to decrease slab vibration. The crane speed is another important issue to influence slab vibration, which decreases with the reduction of the crane speed clearly from the parametric study. Thus, decreasing the crane speed to reduce slab vibration is an alternative, and experiments are caused to find the optimal crane speed and acceleration. The crane induced vibration is the relatively largest and smallest at the column location and beam center, respectively. Therefore, increasing the slab and beam depth to decrease the slab vibration induced by the moving crane is an additional option.

scholarly journals A Finite Element Study on Compressive Resistance Degradation of Square and Circular Steel Braces under Axial Cyclic Loading

2021 ◽  
Vol 11 (13) ◽  
pp. 6094
Author(s):  
Hubdar Hussain ◽  
Xiangyu Gao ◽  
Anqi Shi
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cyclic Loading ◽  
Slenderness Ratio ◽  
Hysteretic Behavior ◽  
Element Analysis ◽  
Section Shape ◽  
Axial Cyclic Loading ◽  
Global Buckling ◽  
Parametric Studies

In this study, detailed finite element analysis was conducted to examine the seismic performance of square and circular hollow steel braces under axial cyclic loading. Finite element models of braces were constructed using ABAQUS finite element analysis (FEA) software and validated with experimental results from previous papers to expand the specimen’s matrix. The influences of cross-section shape, slenderness ratio, and width/diameter-to-thickness ratio on hysteretic behavior and compressive-tensile strength degradation were studied. Simulation results of parametric studies show that both square and circular hollow braces have a better cyclic performance with smaller slenderness and width/diameter-to-thickness ratios, and their compressive-tensile resistances ratio significantly decreases from cycle to cycle after the occurrence of the global buckling of braces.

scholarly journals Development of Nonlinear Finite Element Models of Mortar-Free Interlocked Single Block Column Subjected to Lateral Loading

2021 ◽  
Author(s):  
Furqan Qamar ◽  
Shunde Qin
Keyword(s):  
Finite Element ◽  
Failure Load ◽  
Cost Effective ◽  
Nonlinear Finite Element ◽  
World Population ◽  
Bond Failure ◽  
Lateral Resistance ◽  
Lateral Strength ◽  
Parametric Studies ◽  
Single Block

AbstractAround the globe, the need for additional housing, due to the increase in world population, has led to the exploration of more cost effective and environmentally friendly forms of construction. Out of many technologies found, mortar-free interlocked masonry systems were developed to eliminate the deficiency of traditional masonry. For such systems against earthquakes, lateral resistance can be enhanced with plaster. But there is a need to further improve the performance of plaster in mortar-free interlocking walls for better ductility. The objective of this study is to develop nonlinear finite element (NLFE) models to explore the likely failure mechanism (e.g. bond failure) of such systems and to do parametric studies more cheaply than constructing many walls. Lateral failure load, load–displacement curves and crack patterns were compared with the experimental results. Parametric studies involving variation in block and plaster compressive strength and plaster thickness were undertaken using TNO DIANA NLFE models. A 150% increase in thickness of plaster only resulted in 28% increase in failure load, and column thickness can be reduced to theoretical 25 mm of blocks with 8 mm of plaster and yet exceed the lateral strength of a 150-mm-thick unplastered column. A cost analysis was also carried out, based on NLFE models, and showed that fibrous plastered column with 25-mm-thickness blocks gave equivalent performance to the 150-mm-thick unplastered column with 67% cost saving.

Wear Modeling of Nanometer Thick Protective Coatings

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Jungkyu Lee ◽  
Youfeng Zhang ◽  
Robert M. Crone ◽  
Narayanan Ramakrishnan ◽  
Andreas A. Polycarpou
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Protective Coatings ◽  
Element Model ◽  
Disk Surface ◽  
Magnetic Storage ◽  
Theoretical Frameworks ◽  
Storage Devices ◽  
Parametric Studies ◽  
Magnetic Storage Devices

Use of nanometer thin films has received significant attention in recent years because of their advantages in controlling friction and wear. There have been significant advances in applications such as magnetic storage devices, and there is a need to explore new materials and develop experimental and theoretical frameworks to better understand nanometer thick coating systems, especially wear characteristics. In this work, a finite element model is developed to simulate the sliding wear between the protruded pole tip in a recording head (modeled as submicrometer radius cylinder) and a rigid asperity on the disk surface. Wear is defined as plastically deformed asperity and material yielding. Parametric studies reveal the effect of the cylindrical asperity geometry, material properties, and contact severity on wear. An Archard-type wear model is proposed, where the wear coefficients are directly obtained through curve fitting of the finite element model, without the use of an empirical coefficient. Limitations of such a model are also discussed.

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