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Publications (10 of 14) Show all publications
Hossein Nia, S., S. Sichani, M., Casanueva, C. & Stichel, S. (2018). Wheel life prediction model – an alternative to the FASTSIM algorithm for RCF. Vehicle System Dynamics, 56(7), 1051-1071
Open this publication in new window or tab >>Wheel life prediction model – an alternative to the FASTSIM algorithm for RCF
2018 (English)In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 56, no 7, p. 1051-1071Article in journal (Refereed) Published
Abstract [en]

In this article, a wheel life prediction model considering wear and rolling contact fatigue (RCF) is developed and applied to a heavy-haul locomotive. For wear calculations, a methodology based on Archard's wear calculation theory is used. The simulated wear depth is compared with profile measurements within 100,000km. For RCF, a shakedown-based theory is applied locally, using the FaStrip algorithm to estimate the tangential stresses instead of FASTSIM. The differences between the two algorithms on damage prediction models are studied. The running distance between the two reprofiling due to RCF is estimated based on a Wohler-like relationship developed from laboratory test results from the literature and the Palmgren-Miner rule. The simulated crack locations and their angles are compared with a five-year field study. Calculations to study the effects of electro-dynamic braking, track gauge, harder wheel material and the increase of axle load on the wheel life are also carried out.

Place, publisher, year, edition, pages
Taylor & Francis, 2018
Keywords
RCF, wear, rolling contact, heavy haul, FASTSIM, FaStrip
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-220340 (URN)10.1080/00423114.2017.1403636 (DOI)000432220800004 ()
Note

QC 20171219

Available from: 2017-12-18 Created: 2017-12-18 Last updated: 2018-05-31Bibliographically approved
Shahzamanian Sichani, M., Enblom, R. & Berg, M. (2016). An alternative to FASTSIM for tangential solution of the wheel–rail contact. Vehicle System Dynamics, 54(6), 748-764
Open this publication in new window or tab >>An alternative to FASTSIM for tangential solution of the wheel–rail contact
2016 (English)In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 54, no 6, p. 748-764Article in journal (Refereed) Published
Abstract [en]

In most rail vehicle dynamics simulation packages, tangential solution of the wheel–rail contact is gained by means of Kalker's FASTSIM algorithm. While 5–25% error is expected for creep force estimation, the errors of shear stress distribution, needed for wheel–rail damage analysis, may rise above 30% due to the parabolic traction bound. Therefore, a novel algorithm named FaStrip is proposed as an alternative to FASTSIM. It is based on the strip theory which extends the two-dimensional rolling contact solution to three-dimensional contacts. To form FaStrip, the original strip theory is amended to obtain accurate estimations for any contact ellipse size and it is combined by a numerical algorithm to handle spin. The comparison between the two algorithms shows that using FaStrip improves the accuracy of the estimated shear stress distribution and the creep force estimation in all studied cases. In combined lateral creepage and spin cases, for instance, the error in force estimation reduces from 18% to less than 2%. The estimation of the slip velocities in the slip zone, needed for wear analysis, is also studied. Since FaStrip is as fast as FASTSIM, it can be an alternative for tangential solution of the wheel–rail contact in simulation packages.

Place, publisher, year, edition, pages
Taylor & Francis, 2016
Keywords
creep curve, FASTSIM, rolling contact, strip theory, vehicle dynamics, Wheel–rail contact
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-187266 (URN)10.1080/00423114.2016.1156135 (DOI)000379041100003 ()2-s2.0-84961226665 (Scopus ID)
Note

QC 20160519

Available from: 2016-05-19 Created: 2016-05-19 Last updated: 2017-11-30Bibliographically approved
Shahzamanian Sichani, M. (2016). On Efficient Modelling of Wheel-Rail Contact in Vehicle Dynamics Simulation. (Doctoral dissertation). Stockholm: KTH Royal Institute of Technology
Open this publication in new window or tab >>On Efficient Modelling of Wheel-Rail Contact in Vehicle Dynamics Simulation
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The wheel-rail contact is at the core of all research related to vehicletrackinteraction. This tiny interface governs the dynamic performanceof rail vehicles through the forces it transmits and, like any high stressconcentration zone, it is subjected to serious damage phenomena. Thus,a clear understanding of the rolling contact between wheel and rail is keyto realistic vehicle dynamics simulation and damage analysis.

In a multi-body dynamics simulation, the demanding contact problemshould be evaluated at about every millisecond for several wheel-rail pairs.Hence, a rigorous treatment of the contact is highly time-consuming.Simplifying assumptions are therefore made to accelerate the simulationprocess. This gives rise to a trade-o between the accuracy and computationaleciency of the contact model in use.

Conventionally, Hertz+FASTSIM is used for calculation of the contactforces thanks to its low computational cost. However, the elliptic patchand pressure distribution obtained by Hertz' theory is often not realisticin wheel-rail contact. Moreover, the use of parabolic traction bound inFASTSIM causes considerable error in the tangential stress estimation.This combination leads to inaccurate damage predictions.

Fast non-elliptic contact models are proposed by others to tacklethis issue while avoiding the tedious numerical procedures. The studiesconducted in the present work show that the accuracy of these models iscase-dependent.

To improve the accuracy of non-elliptic patch and pressure estimation,a new method is proposed. The method is implemented in an algorithmnamed ANALYN. Comparisons show improvements in patch and, particularly,pressure estimations using ANALYN.

In addition, an alternative to the widely-used FASTSIM is developed, named FaStrip. Unlike FASTSIM, it employs an elliptic traction boundand is able to estimate the non-linear characteristic of tangential stressdistribution. Comparisons show more accurate estimation of tangentialstress and slip velocity distribution as well as creep forces with FaStrip.

Ultimately, an ecient non-elliptic wheel-rail contact model consistingof ANALYN and FaStrip is proposed. The reasonable computationalcost of the model enables it to be used on-line in dynamics simulationand its accuracy can improve the damage predictions.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. p. xiv, 97
Series
TRITA-AVE, ISSN 1651-7660 ; 2016:02
Keywords
wheel-rail contact, non-elliptic contact, rail vehicle dynamics, rolling contact, vehicle-track interaction, wheel-rail damage
National Category
Vehicle Engineering Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Järnvägsgruppen - Fordonsteknik; The KTH Railway Group - Tribology; Vehicle and Maritime Engineering
Identifiers
urn:nbn:se:kth:diva-181691 (URN)978-91-7595-846-0 (ISBN)
Public defence
2016-02-24, F3, Lindstedsvägen 26, KTH, Stockholm, 13:15 (English)
Opponent
Supervisors
Note

QC 20160202

Available from: 2016-02-02 Created: 2016-02-02 Last updated: 2018-01-10Bibliographically approved
Burgelman, N., Sichani, M. S., Enblom, R., Berg, M., Li, Z. & Dollevoet, R. (2015). Influence of wheel-rail contact modelling on vehicle dynamic simulation. Vehicle System Dynamics, 53(8), 1190-1203
Open this publication in new window or tab >>Influence of wheel-rail contact modelling on vehicle dynamic simulation
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2015 (English)In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 53, no 8, p. 1190-1203Article in journal (Refereed) Published
Abstract [en]

This paper presents a comparison of four models of rolling contact used for online contact force evaluation in rail vehicle dynamics. Until now only a few wheel-rail contact models have been used for online simulation in multibody software (MBS). Many more models exist and their behaviour has been studied offline, but a comparative study of the mutual influence between the calculation of the creep forces and the simulated vehicle dynamics seems to be missing. Such a comparison would help researchers with the assessment of accuracy and calculation time. The contact methods investigated in this paper are FASTSIM, Linder, Kik-Piotrowski and Stripes. They are compared through a coupling between an MBS for the vehicle simulation and Matlab for the contact models. This way the influence of the creep force calculation on the vehicle simulation is investigated. More specifically this study focuses on the influence of the contact model on the simulation of the hunting motion and on the curving behaviour.

National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-171252 (URN)10.1080/00423114.2015.1039550 (DOI)000357332800006 ()2-s2.0-84929429189 (Scopus ID)
Note

QC 20150728

Available from: 2015-07-28 Created: 2015-07-27 Last updated: 2017-12-04Bibliographically approved
Sichani, M. S., Enblom, R. & Berg, M. (2015). Wheel-rail contact modeling for damage predictions in dynamics simulation software. In: CM 2015 - 10th International Conference on Contact Mechanics of Wheel / Rail Systems: . Paper presented at 10th International Conference on Contact Mechanics of Wheel / Rail Systems, CM 2015; Cheyenne Mountain Resort Colorado Springs; United States. International Conference on Contact Mechanics of Wheel
Open this publication in new window or tab >>Wheel-rail contact modeling for damage predictions in dynamics simulation software
2015 (English)In: CM 2015 - 10th International Conference on Contact Mechanics of Wheel / Rail Systems, International Conference on Contact Mechanics of Wheel , 2015Conference paper, Published paper (Refereed)
Abstract [en]

A novel wheel-rail contact model is proposed to be implemented for multi-body dynamics simulation, in order to facilitate accurate online calculation of damage phenomena such as wear and rolling contact fatigue. The normal contact, i.e. contact patch and pressure distribution, is calculated using a fast non-elliptic algorithm called ANALYN. The tangential contact, i.e. tangential stress distribution, stick-slip division and creep force calculation, is treated using an alternative to the FASTSIM algorithm that is based on a strip theory which extends the exact two-dimensional solution of rolling contact to three-dimensional contacts. The proposed contact model is compared to the Kik-Piotrowski model and evaluated using the CONTACT code in terms of contact patch and stress distribution as well as creep force curves. The results show that the proposed model can significantly improve the estimation of the contact solution both in terms of creep force estimation and contact details, such as stress distribution, needed for damage predictions.

Place, publisher, year, edition, pages
International Conference on Contact Mechanics of Wheel, 2015
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-187406 (URN)2-s2.0-84963603461 (Scopus ID)
Conference
10th International Conference on Contact Mechanics of Wheel / Rail Systems, CM 2015; Cheyenne Mountain Resort Colorado Springs; United States
Note

QC 20160525

Available from: 2016-05-25 Created: 2016-05-23 Last updated: 2016-05-25Bibliographically approved
Shahzamanian Sichani, M., Enblom, R. & Berg, M. (2014). A novel method to model wheel-rail normal contact in vehicle dynamics simulation. Vehicle System Dynamics, 52(12), 1752-1764
Open this publication in new window or tab >>A novel method to model wheel-rail normal contact in vehicle dynamics simulation
2014 (English)In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 52, no 12, p. 1752-1764Article in journal (Refereed) Published
Abstract [en]

An approximate analytical method is proposed for calculating the contact patch and pressure distribution in the wheel-rail interface. The deformation of the surfaces in contact is approximated using the separation between them. This makes it possible to estimate the contact patch analytically. The contact pressure distribution in the rolling direction is assumed to be elliptic with its maximum calculated by applying Hertz' solution locally. The results are identical to Hertz's for elliptic cases. In non-elliptic cases good agreement is achieved in comparison to the more accurate but computationally expensive Kalker's variational method (CONTACT code). Compared to simplified non-elliptic contact methods based on virtual penetration, the calculated contact patch and pressure distribution are markedly improved. The computational cost of the proposed method is significantly lower than the more detailed methods, making it worthwhile to be applied to rolling contact in rail vehicle dynamics simulation. Such fast and accurate estimation of contact patch and pressure paves the way for on-line modelling of damage phenomena in dynamics simulation packages.

Keywords
rail vehicle dynamics, Hertz, non-elliptic contact, wheel-rail contact
National Category
Vehicle Engineering
Research subject
Järnvägsgruppen - Fordonsteknik
Identifiers
urn:nbn:se:kth:diva-157589 (URN)10.1080/00423114.2014.961932 (DOI)000345075000011 ()2-s2.0-84911498531 (Scopus ID)
Note

QC 20150623

Available from: 2014-12-12 Created: 2014-12-11 Last updated: 2017-12-05Bibliographically approved
Sh. Sichani, M., Enblom, R. & Berg, M. (2014). Comparison of non-elliptic contact models: Towards fast and accurate modelling of wheel-rail contact. Wear, 314(1-2), 111-117
Open this publication in new window or tab >>Comparison of non-elliptic contact models: Towards fast and accurate modelling of wheel-rail contact
2014 (English)In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 314, no 1-2, p. 111-117Article in journal (Refereed) Published
Abstract [en]

The demand to investigate and predict the surface deterioration phenomena in the wheel-rail interface necessitates fast and accurate contact modelling. During the past 20 years, there have been attempts to determine more realistic contact patch and stress distributions using fast simplified methods. The main aim of the present work is to compare some of these state-of-the-art, non-elliptic contact models available in the literature. This is considered as the first step to develop a fast and accurate non-elliptic contact model that can be used on-line with vehicle dynamics analysis. Three contact models, namely STRIPES, Kik-Piotrowski and Linder are implemented and compared in terms of contact patch prediction, as well as contact pressure and traction distributions. The evaluation of these models using CONTACT software indicate the need for improvement of contact patch and pressure estimation in certain contact cases.

Keywords
Modelling, Non-elliptic contact, Rail vehicle dynamics, Rolling contact, Wheel-rail contact
National Category
Vehicle Engineering Tribology (Interacting Surfaces including Friction, Lubrication and Wear) Applied Mechanics
Research subject
The KTH Railway Group - Tribology; Järnvägsgruppen - Fordonsteknik
Identifiers
urn:nbn:se:kth:diva-127947 (URN)10.1016/j.wear.2013.11.047 (DOI)000337018100015 ()2-s2.0-84898787850 (Scopus ID)
Note

QC 20140520. Updated from manuscript to article in journal.

Available from: 2013-09-09 Created: 2013-09-09 Last updated: 2018-01-11Bibliographically approved
Shahzamanian Sichani, M., Enblom, R. & Berg, M. (2014). Non-Elliptic Wheel-Rail Contact Modelling in Vehicle Dynamics Simulation. The international Journal of railway technology, 3(3), 77-94
Open this publication in new window or tab >>Non-Elliptic Wheel-Rail Contact Modelling in Vehicle Dynamics Simulation
2014 (English)In: The international Journal of railway technology, ISSN 2049-5358, E-ISSN 2053-602X, Vol. 3, no 3, p. 77-94Article in journal (Refereed) Published
Abstract [en]

An approximate rolling contact model is introduced for fast evaluation of the contactpatch and stress distribution in the wheel-rail interface, capable of being usedon-line with dynamics simulations. The normal part of the model is based on a novelapproach in which the surface deformations are approximated, resulting in accuratepatch and pressure estimation. The tangential part is based on an adaptation of FASTSIMalgorithm to non-elliptic patches. The new model is compared to the approximatemodel of Kik and Piotrowski and the results are evaluated using Kalker’s CONTACTcode. The comparison clearly shows that the new model is more accurate than Kikand Piotrowski’s in terms of contact patch and stress distribution as well as creepforce estimation.

National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-181013 (URN)
Note

QC 20160202

Available from: 2016-01-26 Created: 2016-01-26 Last updated: 2017-11-30Bibliographically approved
Burgelman, N., Sichani, M., Li, Z., Dollevoet, R., Enblom, R. & Berg, M. (2013). Comparison of wheel/rail contact models applied for online vehicle dynamic simulation. In: : . Paper presented at 23nd International Symposium on Dynamics of Vehicles on Roads and Tracks (IAVSD 2013); Qingdao, China, 19-28 August, 2013.
Open this publication in new window or tab >>Comparison of wheel/rail contact models applied for online vehicle dynamic simulation
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2013 (English)Conference paper, Published paper (Refereed)
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-138855 (URN)
Conference
23nd International Symposium on Dynamics of Vehicles on Roads and Tracks (IAVSD 2013); Qingdao, China, 19-28 August, 2013
Note

NQC 2014

Available from: 2013-12-20 Created: 2013-12-20 Last updated: 2014-03-24Bibliographically approved
Shahzamanian Sichani, M. (2013). Wheel-rail contact modelling in vehicle dynamics simulation. (Licentiate dissertation). Stockholm: KTH Royal Institute of Technology
Open this publication in new window or tab >>Wheel-rail contact modelling in vehicle dynamics simulation
2013 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The wheel-rail contact is at the core of all research related to vehicle-track interaction. This tiny interface governs the dynamic performance of rail vehicles through the loads it transmits and, like any high stress concentration zone, it is subjected to serious damage phenomena. Thus, a clear understanding of the rolling contact between wheel and rail is key to realistic vehicle dynamic simulation and damage analyses.

In a multi-body-system simulation package, the essentially demanding contact problem should be evaluated in about every millisecond. Hence, a rigorous treatment of the contact is highly time consuming. Simplifying assumptions are, therefore, made to accelerate the simulation process. This gives rise to a trade-off between accuracy and computational efficiency of the contact models in use.

Historically, Hertz contact solution is used since it is of closed-form. However, some of its underlying assumptions may be violated quite often in wheel-rail contact. The assumption of constant relative curvature which leads to an elliptic contact patch is of this kind. Fast non-elliptic contact models are proposed by others to lift this assumption while avoiding the tedious numerical procedures. These models are accompanied by a simplified approach to treat tangential tractions arising from creepages and spin.

In this thesis, in addition to a literature survey presented, three of these fast non-elliptic contact models are evaluated and compared to each other in terms of contact patch, pressure and traction distributions as well as the creep forces. Based on the conclusions drawn from this evaluation, a new method is proposed which results in more accurate contact patch and pressure distribution estimation while maintaining the same computational efficiency. The experience gained through this Licentiate work illuminates future research directions among which, improving tangential contact results and treating conformal contacts are given higher priority.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. p. xi, 55
Series
Trita-AVE, ISSN 1651-7660 ; 2013:47
Keywords
wheel-rail contact, non-elliptic contact, vehicle-track interaction, rail vehicle dynamics, rolling contact, MBS, virtual penetration
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear) Vehicle Engineering Applied Mechanics
Research subject
Järnvägsgruppen - Fordonsteknik; The KTH Railway Group - Tribology
Identifiers
urn:nbn:se:kth:diva-127949 (URN)978-91-7501-852-2 (ISBN)
Presentation
2013-10-02, E2, Lindstedsvägen 3, KTH, Stockholm, 13:15 (English)
Opponent
Supervisors
Note

QC 20130911

Available from: 2013-09-11 Created: 2013-09-09 Last updated: 2018-01-11Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2590-3698

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