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Hazar, S., Alfredsson, B. & Lai, J. (2019). Martensite transformation in the fatigue fracture surface of a high strength bearing steel. Engineering Fracture Mechanics, 220, Article ID UNSP 106650.
Open this publication in new window or tab >>Martensite transformation in the fatigue fracture surface of a high strength bearing steel
2019 (English)In: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 220, article id UNSP 106650Article in journal (Refereed) Published
Abstract [en]

Phase transformation of retained austenite (RA) to martensite was studied considering both stress and strain induced transformations during fatigue crack propagation. X-ray diffraction measurements, performed on the fatigue crack surface obtained through push-pull experiments, showed that almost all RA in the fatigue surface transformed to martensite. A material model that can simulate the phase change including nonlinear isotropic and kinematic hardening behaviors and nonlinear elasticity was used to simulate the fatigue crack growth. Numerical results showed that only a very small amount of RA remained in the crack surface, which agreed with the X-ray diffraction measurements. The effect of phase transformation on crack closure was studied and it was observed in the FE simulations that the crack faces close at an earlier stage when phase change has been taken into account than when it is absent.

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2019
Keywords
Fatigue, Transformation induced plasticity, Stress and strain induced phase transformation, Transformation induced crack closure
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-261936 (URN)10.1016/j.engfracmech.2019.106650 (DOI)000487813100025 ()2-s2.0-85071975359 (Scopus ID)
Note

QC 20191015

Available from: 2019-10-15 Created: 2019-10-15 Last updated: 2019-10-15Bibliographically approved
Everitt, C.-M. & Alfredsson, B. (2019). Surface initiation of rolling contact fatigue at asperities considering slip, shear limit and thermal elastohydrodynamic lubrication. Tribology International, 137, 76-93
Open this publication in new window or tab >>Surface initiation of rolling contact fatigue at asperities considering slip, shear limit and thermal elastohydrodynamic lubrication
2019 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 137, p. 76-93Article in journal (Refereed) Published
Abstract [en]

A numerical investigation was performed, with single axisymmetric asperities passing through lubricated rolling contacts at different slip. Two explanatory and cooperating phenomena were found as to why the damage develops more frequently at negative than positive slip. Metal contact occurred in the inlet, where tractive asperity contacts at negative slip provided a large tensile surface stress outside the contact. As the asperity moved through the contact, sliding supplied it with lubricant and heated the lubricant along the contact. The shear tractions were thus higher near the inlet than the outlet, making them more detrimental for negative than positive slip.

Place, publisher, year, edition, pages
Elsevier Ltd, 2019
Keywords
Contact mechanics, Pitting, Rolling contact fatigue, Sliding, Thermal elastohydrodynamic
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Identifiers
urn:nbn:se:kth:diva-252461 (URN)10.1016/j.triboint.2019.04.023 (DOI)000472686000009 ()2-s2.0-85064836204 (Scopus ID)
Note

QC 20190715

Available from: 2019-07-15 Created: 2019-07-15 Last updated: 2019-07-15Bibliographically approved
Sedlak, M., Alfredsson, B. & Efsing, P. (2018). A cohesive element with degradation controlled shape of the traction separation curve for simulating stress corrosion and irradiation cracking. Engineering Fracture Mechanics, 193, 172-196
Open this publication in new window or tab >>A cohesive element with degradation controlled shape of the traction separation curve for simulating stress corrosion and irradiation cracking
2018 (English)In: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 193, p. 172-196Article in journal (Refereed) Published
Abstract [en]

A cohesive element with extended environmental degradation capability was developed and implemented into an Abaqus user element. The element uses a virgin and a fully degraded Traction Separation Law (TLS) as input. The use of the potential based PPR model enables flexibility in the softening shapes for both TSL. When the element is degraded, the TSL gradually goes from the shape of the virgin material to the fully degraded TSL shape. This transition was made with a new parameter. that can govern a more ductile or brittle crack growth behaviour at degradation. The effect on the plastic zone due to changing the softening shape is shown, where the convex shaped softening TSL gives higher plastic dissipation and larger plastic zones than the concave and more brittle TSL. The new degradation method was evaluated against a Hydrogen Embrittlement (HE) experiment showing improved agreement with the experiment compared to the literature. The effect of different susceptibility zones at the crack tip was also investigated, showing that a uniform degradation throughout the susceptible zone is more influenced by the. parameter than a triangular susceptible zone.

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2018
Keywords
Traction separation law, Intergranular stress corrosion cracking, PPR potential-based, User element, Hydrogen embrittlement
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-225695 (URN)10.1016/j.engfracmech.2018.02.011 (DOI)000427918000013 ()2-s2.0-8504238535 (Scopus ID)
Note

QC 20180411

Available from: 2018-04-11 Created: 2018-04-11 Last updated: 2018-05-22Bibliographically approved
Sedlak, M., Efsing, P. & Alfredsson, B. (2017). Modelling of IGSCC mechanism through coupling of a potential-based cohesive model and Fick’s second law. In: ICF14, Proceedings of the 14th International Conference of Fracture: . Paper presented at The 14th International Conference of Fracture, 18-23 June 2017, Rhodes, Greece. (pp. 689-690). , 1
Open this publication in new window or tab >>Modelling of IGSCC mechanism through coupling of a potential-based cohesive model and Fick’s second law
2017 (English)In: ICF14, Proceedings of the 14th International Conference of Fracture, 2017, Vol. 1, p. 689-690Conference paper, Published paper (Refereed)
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-257969 (URN)9781510878488 (ISBN)
Conference
The 14th International Conference of Fracture, 18-23 June 2017, Rhodes, Greece.
Note

QCR 20191015

Available from: 2019-09-09 Created: 2019-09-09 Last updated: 2019-10-15Bibliographically approved
Linares Arregui, I., Alfredsson, B. & Lai, J. (2015). Low temperature creep in a high strength roller bearing steel.
Open this publication in new window or tab >>Low temperature creep in a high strength roller bearing steel
2015 (English)Report (Other academic)
Series
TRITA-HFL. Report / Royal Institute of Technology, Solid Mechanics, ISSN 1654-1472 ; 570
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-163229 (URN)
Note

QC 20150331

Available from: 2015-03-30 Created: 2015-03-30 Last updated: 2015-03-31Bibliographically approved
Linares Arregui, I. & Alfredsson, B. (2015). Numerical analysis on plasticity induced crack closure of a physically short fatigue crack in a high strength roller bearing steel.
Open this publication in new window or tab >>Numerical analysis on plasticity induced crack closure of a physically short fatigue crack in a high strength roller bearing steel
2015 (English)Report (Other academic)
Series
TRITA-HFL. Report / Royal Institute of Technology, Solid Mechanics, ISSN 1654-1472 ; 571
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-163230 (URN)
Note

QC 20150331

Available from: 2015-03-30 Created: 2015-03-30 Last updated: 2015-03-31Bibliographically approved
Hannes, D. & Alfredsson, B. (2014). A parametric investigation of surface initiated rolling contact fatigue using the asperity point load mechanism. In: Advances in Fracture and Damage Mechanics XII: selected, peer reviewed papers from the 12th International Conference on Fracture and Damage Mechanics (FDM 2013), September 17-19, 2013, Sardinia, Italy. Paper presented at 12th International Conference on Fracture and Damage Mechanics, FDM 2013; Sardinia; Italy; 17 September 2013 through 19 September 2013 (pp. 45-48). Trans Tech Publications Inc.
Open this publication in new window or tab >>A parametric investigation of surface initiated rolling contact fatigue using the asperity point load mechanism
2014 (English)In: Advances in Fracture and Damage Mechanics XII: selected, peer reviewed papers from the 12th International Conference on Fracture and Damage Mechanics (FDM 2013), September 17-19, 2013, Sardinia, Italy, Trans Tech Publications Inc., 2014, p. 45-48Conference paper, Published paper (Refereed)
Abstract [en]

Rolling contact fatigue (RCF) will eventually become an issue for machine elements that are repeatedly over-rolled with high contact loads and small relative sliding motion. The damage consists of cracks and craters in the contact surfaces. Asperities on the contact surfaces act as local stress raisers and provide tensile surface stresses which can explain both initiation and propagation of surface initiated RCF damage. A parametric study was performed to investigate the contribution of surface roughness, friction and a residual surface stress to the RCF damage process. The effects on initiation, crack path and fatigue life at both early and developed damage were examined for a gear application. Both a one-parameter-at-a-time approach and a 2-level full factorial design were carried out. Surface roughness and local friction properties were found to control crack initiation, whereas the simulated crack path was primarily affected by the residual surface stress, especially for developed damage. Reduced surface roughness, improved lubrication and a compressive residual surface stress all contributed to increase the simulated fatigue life. The asperity point load model could predict effects on RCF that are observed with experiments. The results further support the asperity point load mechanism as the source behind surface initiated RCF.

Place, publisher, year, edition, pages
Trans Tech Publications Inc., 2014
Series
Key Engineering Materials, ISSN 1013-9826 ; 577-578
Keywords
Asperity, Crack path, Fatigue life, Friction, Initiation, Rolling contact fatigue
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-145496 (URN)10.4028/www.scientific.net/KEM.577-578.45 (DOI)000336693900012 ()2-s2.0-84888624220 (Scopus ID)978-303785830-1 (ISBN)
Conference
12th International Conference on Fracture and Damage Mechanics, FDM 2013; Sardinia; Italy; 17 September 2013 through 19 September 2013
Note

QC 20140521

Available from: 2014-05-21 Created: 2014-05-21 Last updated: 2014-06-27Bibliographically approved
Hannes, D. & Alfredsson, B. (2014). Numerical investigation of the spall opening angle of surface initiated rolling contact fatigue. Engineering Fracture Mechanics, 131, 538-556
Open this publication in new window or tab >>Numerical investigation of the spall opening angle of surface initiated rolling contact fatigue
2014 (English)In: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 131, p. 538-556Article in journal (Refereed) Published
Abstract [en]

The spall opening angle was studied for surface initiated rolling contact fatigue with the purpose to allow assessment of the volume of detached material. The influence of friction and the crack inclination angle on the damage spread in the contact surface was investigated with the asperity point load mechanism and a simplified three-dimensional rolling contact fatigue load. Crack arrest due to crack closure was proposed as explaining mechanism for the spall opening angle of the typical v-shaped or arrowhead crack configurations. A new three-dimensional crack geometry was presented allowing the study of the spalling surface morphology in a gear application. Stress intensity factors along the crack front were computed using the eXtended Finite Element Method (XFEM) implemented in Abaqus (6.12). Both low crack inclination angles and increased friction resulted in larger spall opening angles. For cracks with small inclination angles the effects of increased friction on the spall opening angle appeared however very little. The findings increase understanding of the surface morphology and the damage process and further motivate the asperity point load mechanism as an important source for surface initiated RCF damage.

Keywords
Rolling contact fatigue, Crack closure, Crack arrest, Finite elements (XFEM), Mixed-mode
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-157601 (URN)10.1016/j.engfracmech.2014.09.010 (DOI)000344987300035 ()2-s2.0-84909606586 (Scopus ID)
Note

QC 20141212

Available from: 2014-12-12 Created: 2014-12-11 Last updated: 2017-12-05Bibliographically approved
Alfredsson, B. & Nordin, E. (2013). An Elastic-Plastic Model for Single Shot-Peening Impacts. Tribology letters, 52(2), 231-251
Open this publication in new window or tab >>An Elastic-Plastic Model for Single Shot-Peening Impacts
2013 (English)In: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 52, no 2, p. 231-251Article in journal (Refereed) Published
Abstract [en]

A model was developed for impacts of elastic perfectly plastic spherical particles with impact velocities up to 250 m/s. The model is based on the two master curves, for normalized pressure and projected contact area c (2), which both are functions of the representative strain I > at maximum impact. The model and its parameters were fitted to finite element results for elastic perfectly plastic and strain rate-independent materials. It was applied to a wide range of materials with different ratio between yield stress and elastic properties, different ball sizes and impact velocities. The impact model predicted the results from finite element method for contact radius, maximum impact depth in both target and ball as well as remaining impact depth in target and ball. The remaining impact depth was determined from elastic spring back with Hertzian and quadratic pressure at maximum impact. The rebound velocity was also estimated by following the load-deformation path during spring back. If the strain rate-compensated yield stress was used for the master curve parameters, then the model predicted the impact results also for the investigated strain rate-dependent materials.

Keywords
Shot peening, Contact mechanics, Impact, Elastic-plastic material, Strain rate hardening
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Identifiers
urn:nbn:se:kth:diva-134562 (URN)10.1007/s11249-013-0209-8 (DOI)000326081700007 ()2-s2.0-84890125078 (Scopus ID)
Note

QC 20131125

Available from: 2013-11-25 Created: 2013-11-25 Last updated: 2018-01-11Bibliographically approved
Hannes, D. & Alfredsson, B. (2013). Modelling of surface initiated rolling contact fatigue damage. In: Fatigue Design 2013, International Conference Proceedings: . Paper presented at 5th International Conference on Fatigue Design, Fatigue Design 2013, 27 November 2013 through 28 November 2013, Senlis, france (pp. 766-774). Elsevier
Open this publication in new window or tab >>Modelling of surface initiated rolling contact fatigue damage
2013 (English)In: Fatigue Design 2013, International Conference Proceedings, Elsevier, 2013, p. 766-774Conference paper, Published paper (Refereed)
Abstract [en]

A parametric study was performed to investigate the contribution of surface roughness, friction and a constant residual surface stress to the rolling contact fatigue damage process. The effects on initiation, crack path and fatigue life were examined for a gear application. The asperity point load model could predict effects on rolling contact fatigue that are observed with experiments. The study of a ring/cone crack subjected to a rolling contact fatigue load allowed to explain the v-shaped cracks typical for surface initiated spalling. The results further support the asperity point load mechanism as a source behind surface initiated rolling contact fatigue.

Place, publisher, year, edition, pages
Elsevier, 2013
Series
Procedia Engineering, ISSN 1877-7058 ; 66
Keywords
Asperity, Crack closure, Crack path, Fatigue life, Initiation, Rolling contact fatigue, Spalling, Surface crack
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:kth:diva-147480 (URN)10.1016/j.proeng.2013.12.130 (DOI)000338327000075 ()2-s2.0-84894412288 (Scopus ID)
Conference
5th International Conference on Fatigue Design, Fatigue Design 2013, 27 November 2013 through 28 November 2013, Senlis, france
Note

QC 20140627

Available from: 2014-06-27 Created: 2014-06-27 Last updated: 2014-08-04Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-6896-1834

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