A New Criterion for Prediction of Train Derailment

2007 ◽  
Author(s):  
Mohammad Durali ◽  
Mohammad Mahdi Jalili
Keyword(s):  
Dynamic Parameters ◽  
Train Derailment ◽  
Derailment Coefficient ◽  
Definition Of ◽  
New Criterion

A new criterion for prediction of train derailment is presented in this paper. A 3 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 offering the required precision in prediction of wheel set derailment, requires measurements which are several times easier. To evaluate the capability of the new criterion in prediction of derailment, it was used to determine derailment of a full wagon model with 48 DOF moving on a rail with different random irregularities. The results were then compared with the predictions of conventional derailment coefficients.

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).

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.

scholarly journals Optimization on the Crosswind Stability of Trains Using Neural Network Surrogate Model

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Le Zhang ◽  
Tian Li ◽  
Jiye Zhang ◽  
Ronghuan Piao
Keyword(s):  
Contact Force ◽  
Surrogate Model ◽  
Lateral Force ◽  
Dynamics Simulation ◽  
Load Reduction ◽  
Dynamic Parameters ◽  
Wheel Load ◽  
Running Safety ◽  
Derailment Coefficient ◽  
Safety Metrics

AbstractUnder the influence of crosswinds, the running safety of trains will decrease sharply, so it is necessary to optimize the suspension parameters of trains. This paper studies the dynamic performance of high-speed trains under crosswind conditions, and optimizes the running safety of train. A computational fluid dynamics simulation was used to determine the aerodynamic loads and moments experienced by a train. A series of dynamic models of a train, with different dynamic parameters were constructed, and analyzed, with safety metrics for these being determined. Finally, a surrogate model was built and an optimization algorithm was used upon this surrogate model, to find the minimum possible values for: derailment coefficient, vertical wheel-rail contact force, wheel load reduction ratio, wheel lateral force and overturning coefficient. There were 9 design variables, all associated with the dynamic parameters of the bogie. When the train was running with the speed of 350 km/h, under a crosswind speed of 15 m/s, the benchmark dynamic model performed poorly. The derailment coefficient was 1.31. The vertical wheel-rail contact force was 133.30 kN. The wheel load reduction rate was 0.643. The wheel lateral force was 85.67 kN, and the overturning coefficient was 0.425. After optimization, under the same running conditions, the metrics of the train were 0.268, 100.44 kN, 0.474, 34.36 kN, and 0.421, respectively. This paper show that by combining train aerodynamics, vehicle system dynamics and many-objective optimization theory, a train’s stability can be more comprehensively analyzed, with more safety metrics being considered.

Minimum entropy deconvolution and simplicity: A noniterative algorithm

Geophysics ◽  
1985 ◽  
Vol 50 (3) ◽  
pp. 394-413 ◽  
Author(s):  
Carlos A. Cabrelli
Keyword(s):  
Synthetic Data ◽  
Computational Method ◽  
Minimum Entropy ◽  
Autocorrelation Matrix ◽  
Numerical Tests ◽  
Convolution Model ◽  
Single Input ◽  
Definition Of ◽  
Single Matrix ◽  
New Criterion

Minimum entropy deconvolution (MED) is a technique developed by Wiggins (1978) with the purpose of separating the components of a signal, as the convolution model of a smooth wavelet with a series of impulses. The advantage of this method, as compared with traditional methods, is that it obviates strong hypotheses over the components, which require only the simplicity of the output. The degree of simplicity is measured with the Varimax norm for factor analysis. An iterative algorithm for computation of the filter is derived from this norm, having as an outstanding characteristic its stability in presence of noise. Geometrical analysis of the Varimax norm suggests the definition of a new criterion for simplicity: the D norm. In case of multiple inputs, the D norm is obtained through modification of the kurtosis norm. One of the most outstanding characteristics of the new criterion, by comparison with the Varimax norm, is that a noniterative algorithm for computation of the deconvolution filter can be derived from the D norm. This is significant because the standard MED algorithm frequently requires in each iteration the inversion of an autocorrelation matrix whose order is the length of the filter, while the new algorithm derived from the D norm requires the inversion of a single matrix. On the other hand, results of numerical tests, performed jointly with Graciela A. Canziani, show that the new algorithm produces outputs of greater simplicity than those produced by the traditional MED algorithm. These considerations imply that the D criterion yields a new computational method for minimum entropy deconvolution. A section of numerical examples is included, where the results of an extensive simulation study with synthetic data are analyzed. The numerical computations show in all cases a remarkable improvement resulting from use of the D norm. The properties of stability in the presence of noise are preserved as shown in the examples. In the case of a single input, the relation between the D norm and the spiking filter is analyzed (Appendix B).

Development of a Criterion for a Robust Identification of Diffuser Rotating Stall Onset in Industrial Centrifugal Compressors

2018 ◽  
Author(s):  
Alessandro Bianchini ◽  
Giulia Andreini ◽  
Giovanni Ferrara ◽  
Lorenzo Ferrari ◽  
Dante Tommaso Rubino
Keyword(s):  
Aerodynamic Force ◽  
Dynamic Pressure ◽  
Safety Margin ◽  
Specific Model ◽  
Rotating Stall ◽  
Centrifugal Compressors ◽  
Stall Inception ◽  
Spectrum Area ◽  
Definition Of ◽  
New Criterion

Recent studies showed that a prompt detection of the stall inception, connected with a specific model to predict its associated aerodynamic force, could provide room for an extension of the left margin of the operating curve of high-pressure centrifugal compressors. In industrial machines working in the field, however, robust procedures to detect and identify the phenomenon are still missing, i.e. the operating curve is almost ever cut preliminary by the manufacturer by a proper safety margin; moreover, no agreement is found in the literature about a well-defined threshold to define the onset of the stall. In particular, in some cases the intensity of the arising subsynchronous frequency is compared to the revolution frequency, while in many other ones it is compared to the blade passage frequency. A large experience in experimental stall analyses collected by the authors revealed that in some cases unexpected spikes could make this direct comparison not reliable for a robust automatic detection. To this end, a new criterion was developed based on an integral analysis of the area subtended to the entire subsynchronous spectrum of the dynamic pressure signal of probes positioned just outside the impeller exit. A dimensionless parameter was then defined to account for the spectrum area increase in proximity to stall inception. This new parameter enabled the definition of a reference threshold to highlight the arising of stall conditions, whose validity and increased robustness was here verified based on a set of experimental analyses of different types of full-stage test cases of industrial centrifugal compressors at the test rig.

Development of a Criterion for a Robust Identification of Diffuser Rotating Stall Onset in Industrial Centrifugal Compressors

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Alessandro Bianchini ◽  
Giulia Andreini ◽  
Lorenzo Ferrari ◽  
Dante Tommaso Rubino ◽  
Giovanni Ferrara
Keyword(s):  
Aerodynamic Force ◽  
Dynamic Pressure ◽  
Safety Margin ◽  
Specific Model ◽  
Rotating Stall ◽  
Centrifugal Compressors ◽  
Stall Inception ◽  
Spectrum Area ◽  
Definition Of ◽  
New Criterion

Recent studies showed that a prompt detection of the stall inception, connected with a specific model to predict its associated aerodynamic force, could provide room for an extension of the left margin of the operating curve of high-pressure centrifugal compressors. In industrial machines working in the field, however, robust procedures to detect and identify the phenomenon are still missing, i.e., the operating curve is almost ever cut preliminarily by the manufacturer by a proper safety margin; moreover, no agreement is found in the literature about a well-defined threshold to define the onset of the stall. In particular, in some cases, the intensity of the arising subsynchronous frequency is compared to the revolution frequency, while in many other ones it is compared to the blade passage frequency. A large experience in experimental stall analyses collected by the authors revealed that in some cases unexpected spikes could make this direct comparison not reliable for a robust automatic detection. To this end, a new criterion was developed based on an integral analysis of the area subtended to the entire subsynchronous spectrum of the dynamic pressure signal of probes positioned just outside the impeller exit. A dimensionless parameter was then defined to account for the spectrum area increase in proximity to stall inception. This new parameter enabled the definition of a reference threshold to highlight the arising of stall conditions, whose validity and increased robustness was here verified based on a set of experimental analyses of different types of full-stage test cases of industrial centrifugal compressors at the test rig.

The Security Study of Train Derailment on High-Speed Railway Bridge

2012 ◽  
Vol 446-449 ◽  
pp. 1144-1147 ◽  
Author(s):  
Yu Sen Lin ◽  
Li Hua Xin
Keyword(s):  
High Speed ◽  
Convergence Criterion ◽  
Railway Bridge ◽  
High Speed Railway ◽  
Train Derailment ◽  
Derailment Coefficient ◽  
Coupling System ◽  
Decrement Rate ◽  
Beam Bridge ◽  
Security Study

In this paper vehicle-bridge coupling system is divided into vehicle system and bridge system. The equations of vehicle vibration and bridge vibration are solved in numerical method, considered the displacement of wheel and rail as convergence criterion. The security of running train is studied on the hand of wheel-rail force, derailment coefficient, load decrement rate of wheel weight, and the reason of train derailing on high-speed railway bridge is analyzed. By the example of multiple span simple supported beam bridge, the result derived by this method is proved that the bridge meet train security and amenity requirement.

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.

Nonlinear Analysis of Train Derailment in Severe Braking

2003 ◽  
Vol 125 (1) ◽  
pp. 48-53 ◽  
Author(s):  
Mohammad Durali ◽  
Baabak Shadmehri
Keyword(s):  
Dry Friction ◽  
Three Dimensional ◽  
Comprehensive Model ◽  
Train Derailment ◽  
Optimum Configuration ◽  
Car Model ◽  
Nonlinear Springs ◽  
Derailment Coefficient ◽  
Complete Set ◽  
Different Parts

A nonlinear comprehensive model has been developed in this paper to study the train derailment and hunting in severe braking conditions. The train consists of cars each having 40 dof, connected to each other by couplers and buffers. The car model is nonlinear and three-dimensional and includes nonlinear springs and dampers of primary and secondary suspensions, dry friction between different parts such as car body and side bearers, center-plate parts, wheelset bearings and bogie frames, and also clearances and mechanical stops. Nonlinearities of wheel and rail profiles, pressure build-up delay in brake circuit, and nonlinearities of connecting parts have also been included in the model. A complete set of equations has been derived for the train. The equations are solved numerically for different car weight configurations when severe brake is applied. Derailment coefficient is determined for several train make-ups and tendency of the wheels towards derailment is investigated. Optimum configuration of cars in a light-heavy set, and critical derailment velocity can be determined to minimize the tendency of train derailment. The results are in excellent agreement with the field experience.

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