Study on longitudinal force simulation of heavy-haul train

Chang, Chongyi; Guo, Gang; Wang, Junbiao; Ma, Yingming

doi:10.1080/00423114.2016.1269183

Cited by 28 publications

(23 citation statements)

References 9 publications

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“…A cross-plot of an experimental drop-hammer tests was provided, and each simulator could describe the coupler behavior according to previous modeling experience with no further restrictions. Some simulators used fixed tables with linear transitions (TABLDSS, 47 UM, 48 VOCO, 49 and TsDyn 50 ), others featured a full non-linear transition path with a logic switch based on the speed value (BODYSIM 51 and CARS 18 ), TDEAS 52 had variable trajectories for loading and unloading curves, depending on the current speed value, and CRE-LTS 53 had the stiffest model with variations in the transitional paths.…”

Section: Simulation Resultsmentioning

confidence: 99%

Development and validation of a new code for longitudinal train dynamics simulation

Bosso

Magelli

Zampieri

2020

Proceedings of the Institution of Mechanical Engineers, Part F:

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Longitudinal train dynamics have a significant impact on both safety and performance of railway systems. Numerical simulation of long heavy haul trains can thus provide essential information for the development of diagnostic and signaling systems as well as coupling elements and braking systems. Long trains are usually modeled by considering only the longitudinal degree of freedom and by adding extra resistant forces to represent the track curvature and gradients. The prediction of in-train forces represents the most critical aspect in modeling the longitudinal dynamics of long trains made up of several vehicles. In fact, coupling elements have non-linear force–deflection characteristics, with different behavior in loading and unloading states, thus featuring a hysteretic loop. Look-up tables storing data from experimental tests are generally used to model these elements; however, other strategies, such as fitting curves and white-box models are witnessed in the literature. Recently, an international benchmarking of longitudinal train dynamics simulator was established in order to compare the output results obtained by different models with the same input data. The research group from Politecnico di Torino performed the simulations using the multibody software Simpack, but computational inefficiencies and numerical divergences occurred. To overcome these issues, a new dedicated in-house code was developed in the MATLAB environment. The paper focuses on the description of this new code and its validation, which was carried out by performing the simulations according to the benchmark inputs and comparing the results with the outputs from the other participants.

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Section: Simulation Resultsmentioning

confidence: 99%

Development and validation of a new code for longitudinal train dynamics simulation

Bosso

Magelli

Zampieri

2020

Proceedings of the Institution of Mechanical Engineers, Part F:

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“…Table 1 Longitudinal compressive forces' maxima (kN) in stretched (numerator) and compressed (denominator) freight trains of different length during running-out, for various algebraic difference of gradients and various initial velocities Using the data provided in Table 1 as well as the dependencies shown in Fig. 6, the following empirical formulae for determining the maxima of compressive longitudinal shock (4) and quasi-static (5) forces during adjustment braking on the concave sections of the profile were obtained: In this figure, solid lines are obtained as a result of numerical integration of the system of nonlinear differential equations of train motion, and dashed lines are obtained using the empirical formula (4). As one can see from Fig.…”

Section: Some Resultsmentioning

confidence: 99%

The Influence of the «train-Track» System Parameters on the Maximum Longitudinal Forces' Level

et al. 2019

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The main objective of the simulation is to study the effect caused by the parameters of the longitudinal profile on the maxima of longitudinal forces in freight trains of increased length during adjustment braking and running-out. To decrease the number of numerical experiments, some empirical formulae for estimating the maximum longitudinal forces during the motion of freight trains along the track with various configurations of its longitudinal profile's gradient changes have been obtained for the first time. Comparison of those forces with the permitted values, from the point of view of the railway stock strength and eventual vehicle derailment, has been performed. As a result of numerical integration of the system of non-linear differential equations of train motion for the considered driving modes, the values of the greatest longitudinal shock and quasi-static forces, as well as the dependence of the latter on the train length, initial braking velocity, on the algebraic difference of gradients and the length of the horizontal area that separates two gradients with opposite signs are estimated. The proposed mathematical model and methodology can be applied during standardization of the longitudinal profile's parameters from the point of view of the freight traffic safety for the trains of various length.

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“…Obviously, more complex models, including the detailed simulation of the vertical and lateral dynamics of each or some vehicles [16]- [18] as well as of the air brake system [19]- [21], are witnessed in the literature; however, in this case, computational efficiency is a prime concern, and parallel or distributed computing techniques are essential to ensure good computing performances [22]- [24].…”

Section: Introductionmentioning

confidence: 99%

Validation of a New Longitudinal Train Dyna Mics Code for Time Domain Simulations and Modal Analyses

Bosso¹,

Magelli²,

Zampieri³

2021

Int. J. TDI

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Large speeds and axle-loads are required for modern freight trains, which can cause a big rise in in-train forces on wagon coupling elements for both tensile and compressive states, thus possibly leading to breaking of the coupling systems and to train derailments, respectively. Therefore, longitudinal train dynamics (LTD) simulations are a key tool for the prediction of the in-train forces and for the design of coupling and braking systems as well as for the optimization of the train composition. LTD simulations are typically carried out in time domain, to account for all the system non-linearities, mainly the hysteretic behaviour of the coupling system mechanical impedance characteristic. Although time domain simulations are a powerful tool to predict in-train forces considering all the system non-linearities, also frequency domain analyses can be useful to quickly compute the system dynamic behaviour. More in detail, modal analysis can provide important information on the system natural frequencies, so that the frequency content of the input forces can be checked to avoid the excitation of the system natural vibration modes.The paper shows the development of a new efficient time domain simulation LTD code implemented in MATLAb, provided with a modal analysis post-processing routine. The code was validated on the four time domain simulation scenarios suggested by the international benchmark of LTD simulators, and a simplified modal analysis was also carried out on the same train configurations. The validation process highlighted that the new code provides stable numerical outputs with a good computational efficiency, while the modal analysis routine showed that the train eigenfrequencies can vary significantly according to the deflection, relative speed and loading state on each coupler.

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Study on longitudinal force simulation of heavy-haul train

Cited by 28 publications

References 9 publications

Development and validation of a new code for longitudinal train dynamics simulation

Development and validation of a new code for longitudinal train dynamics simulation

The Influence of the «train-Track» System Parameters on the Maximum Longitudinal Forces' Level

Validation of a New Longitudinal Train Dyna Mics Code for Time Domain Simulations and Modal Analyses

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