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Crack Growth Paths in Rolling Contact Fatigue - Numerical Predictions.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Crack Growth Paths in Rolling Contact Fatigue - Numerical Predictions./
Author:	Nezhad, Mohammad Salahi.
Description:	1 online resource (30 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 84-01, Section: B.
Contained By:	Dissertations Abstracts International84-01B.
Subject:	Physics. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=29177718click for full text (PQDT)
ISBN:	9798835547241

Crack Growth Paths in Rolling Contact Fatigue - Numerical Predictions.
Nezhad, Mohammad Salahi.

Crack Growth Paths in Rolling Contact Fatigue - Numerical Predictions. - 1 online resource (30 pages)

Source: Dissertations Abstracts International, Volume: 84-01, Section: B.

Thesis (Licentiate)--Chalmers Tekniska Hogskola (Sweden), 2022.

Includes bibliographical references

Rolling contact fatigue (RCF) cracks in railway wheels and rails are costly and complex to deal with. Despite the extensive research efforts that have been put into understanding the mechanisms and developing appropriate predictive models for RCF crack growth, there are still a lot of open questions. This is the case regarding the direction and growth rate of RCF crack propagation under multiaxial wheel‒rail contact loading, which also interplays with rail bending and thermal loads during the operational life of a rail.In the first paper of this thesis (Paper A), a numerical procedure is developed to evaluate the effect of different operational loading scenarios on the predicted crack paths in rails. A 2D linear elastic finite element model of a rail part with an inclined surface-breaking crack has been implemented. The rail part is subjected to wheel‒rail contact load, rail bending, and temperature drop as isolated scenarios and in combinations. The effective crack propagation direction is predicted based on an accumulative Vector Crack Tip Displacement (VCTD) criterion that accounts for crack face locking effects through a reversed shear threshold parameter. It has been shown that the crack path for combined thermal and contact loads varies gradually between the pure load cases while the combination of bending and contact loading has an abrupt change in predicted crack paths. Furthermore, the dependency of the results on the reversed shear threshold parameter is investigated.The influence of crack face friction on the crack path is investigated in the second paper (Paper B). The numerical procedure developed in Paper A is utilised, and crack face friction is modelled by a Coulomb friction model. Qualitative predictions are obtained for varying magnitude of the coefficient of friction, as well as for varying parameters of the crack growth criterion. It is observed that the frictional crack tends to go deeper into the rail under a pure contact load and for a combination of bending and contact loads, while the friction has a moderate influence on the crack path for combined thermal and contact loads. Furthermore, assessment of the ranges of crack face deformation indicates that friction reduces the crack growth rate.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2023

Mode of access: World Wide Web

ISBN: 9798835547241Subjects--Topical Terms:

516296
Physics.
Index Terms--Genre/Form:

542853
Electronic books.

Crack Growth Paths in Rolling Contact Fatigue - Numerical Predictions.
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100 1 $a Nezhad, Mohammad Salahi. $3 3693527
245 1 0 $a Crack Growth Paths in Rolling Contact Fatigue - Numerical Predictions.
264 0 $c 2022
300 $a 1 online resource (30 pages)
336 $a text $b txt $2 rdacontent
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500 $a Source: Dissertations Abstracts International, Volume: 84-01, Section: B.
500 $a Advisor: Larsson, Fredrik;Kabo, Elena;Ekberg, Anders.
502 $a Thesis (Licentiate)--Chalmers Tekniska Hogskola (Sweden), 2022.
504 $a Includes bibliographical references
520 $a Rolling contact fatigue (RCF) cracks in railway wheels and rails are costly and complex to deal with. Despite the extensive research efforts that have been put into understanding the mechanisms and developing appropriate predictive models for RCF crack growth, there are still a lot of open questions. This is the case regarding the direction and growth rate of RCF crack propagation under multiaxial wheel‒rail contact loading, which also interplays with rail bending and thermal loads during the operational life of a rail.In the first paper of this thesis (Paper A), a numerical procedure is developed to evaluate the effect of different operational loading scenarios on the predicted crack paths in rails. A 2D linear elastic finite element model of a rail part with an inclined surface-breaking crack has been implemented. The rail part is subjected to wheel‒rail contact load, rail bending, and temperature drop as isolated scenarios and in combinations. The effective crack propagation direction is predicted based on an accumulative Vector Crack Tip Displacement (VCTD) criterion that accounts for crack face locking effects through a reversed shear threshold parameter. It has been shown that the crack path for combined thermal and contact loads varies gradually between the pure load cases while the combination of bending and contact loading has an abrupt change in predicted crack paths. Furthermore, the dependency of the results on the reversed shear threshold parameter is investigated.The influence of crack face friction on the crack path is investigated in the second paper (Paper B). The numerical procedure developed in Paper A is utilised, and crack face friction is modelled by a Coulomb friction model. Qualitative predictions are obtained for varying magnitude of the coefficient of friction, as well as for varying parameters of the crack growth criterion. It is observed that the frictional crack tends to go deeper into the rail under a pure contact load and for a combination of bending and contact loads, while the friction has a moderate influence on the crack path for combined thermal and contact loads. Furthermore, assessment of the ranges of crack face deformation indicates that friction reduces the crack growth rate.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2023
538 $a Mode of access: World Wide Web
650 4 $a Physics. $3 516296
650 4 $a Load. $3 3562902
650 4 $a Friction. $3 650299
650 4 $a Propagation. $3 3680519
650 4 $a Crack initiation. $3 3564902
650 4 $a Pressure distribution. $3 3564852
650 4 $a Energy. $3 876794
650 4 $a Crack propagation. $3 3683840
650 4 $a Mechanics. $3 525881
655 7 $a Electronic books. $2 lcsh $3 542853
690 $a 0791
690 $a 0338
690 $a 0346
690 $a 0605
710 2 $a ProQuest Information and Learning Co. $3 783688
710 2 $a Chalmers Tekniska Hogskola (Sweden). $3 1913472
773 0 $t Dissertations Abstracts International $g 84-01B.
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=29177718 $z click for full text (PQDT)