A numerical approach to subsurface crack propagation assessment in rolling contact

Rolling contact fatigue (RCF) is one of the most important failure mechanisms in rails with significant cost‐ and safety‐related implications on the operation of railway systems. In this work, a metallurgical analysis of RCF crack initiation and propagation, including geometrical characteristics of RCF cracks – length, depth from surface, angle of propagation and spacing between cracks, is presented. The role of proeutectoid ferrite in crack initiation has been studied. Analysis of the fracture surface of an RCF crack revealed a ductile initiation zone followed by a quasi‐cleavage crack propagation. Iron oxide formed in the interior of all cracks in rails exposed to stagnant water with implications to crack propagation rate because of crack closure effects. Sequential sectioning parallel to the rolling surface revealed that RCF cracks possess convoluted surfaces. The crack trace expands with depth from the rolling surface. Subsurface crack initiation has also been documented.

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“…Subsurface fatigue crack initiation has also been considered recently by Mazzu. 26 Similar observations are depicted in Fig. 12 for crack no.…”

Section: R E S U L T S a N D Discussionsupporting

confidence: 83%

“…1s, appears at section S3, indicating that subsurface crack initiation also takes place in addition to surface‐nucleated cracks. Subsurface fatigue crack initiation has also been considered recently by Mazzu …”

Section: Resultsmentioning

confidence: 99%

Rolling contact fatigue cracking in rails subjected to in‐service loading

Haidemenopoulos

Sarafoglou

Christopoulos

et al. 2016

Fatigue Fract Eng Mat Struct

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“…For example, Bao et al estimated the SIFs due to residual stresses of the welding using WFM. Additionally, Mazuu determined mode II SIFs of a subsurface crack under rolling pressure to evaluate the fatigue crack growth. In addition, Kasivitamnuay investigated the circumferential cracks in cylinders under complex loadings utilizing one‐dimensional WFs.…”

Section: Introductionmentioning

confidence: 99%

“…The current study aims to investigate one‐dimensional subsurface cracks in a semi‐infinite plane under arbitrary distributions of normal and shear loading. To this end, a new general form of WF is proposed and very simple one‐dimensional WFs, compared with the existing WFs, are derived for considering both crack tips under symmetrical and non‐symmetrical loadings. The presented WFs are capable to calculate the SIFs of a subsurface crack for all lengths and depths.…”

Section: Introductionmentioning

confidence: 99%

A new weight function for one‐dimensional subsurface cracks under general loading

Abdoli

Khezri

Kaklar

2019

Fatigue Fract Eng Mat Struct

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In the present study, weight functions (WFs) of a subsurface crack were derived by proposing a new general form for approximate one‐dimensional WF. The WFs coefficients were considered as a function of crack length to depth ratio and were obtained using reference stress intensity factors (SIFs) of 16 cracks under uniform, linear, and parabolic normal and shearing loadings. The verification was performed by comparison of the straight and coupled SIFs calculated by WF and finite element modelling under some complicated loadings. In conclusion, the WFs can be simply and effectively employed for evaluating the cracks under any complex stress distributions.

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“…RCF tests were carried out on cylindrical discs with diameter of 60 mm and 15 mm thick. Other interesting papers have been presented by the same authors regarding numerical approaches, models, and failure assessment of rolling contact fatigue and wear [17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%