Very high cycle fatigue – Is there a fatigue limit?

Pyttel, Brita; Schwerdt, Daniela; Berger, Christina

doi:10.1016/j.ijfatigue.2010.05.009

Cited by 250 publications

(155 citation statements)

References 26 publications

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“…These works confirmed or verified that the present study is very important, especially the reliability analysis of corrosion fatigue data of high speed railway axle [2]. Pyttel et al [15] determined that the surface fatigue strength during high cycle fatigue (10 5 -10 7 ) (HCF) and the volume fatigue strength during VHCF (>10 7 ) should be studied in detail and presented a design or prediction processes for the entire fatigue life of metals. However, Pyttel et al [15] also discussed the existence of a fatigue limit for metals.…”

Section: Introductionsupporting

confidence: 82%

“…Pyttel et al [15] determined that the surface fatigue strength during high cycle fatigue (10 5 -10 7 ) (HCF) and the volume fatigue strength during VHCF (>10 7 ) should be studied in detail and presented a design or prediction processes for the entire fatigue life of metals. However, Pyttel et al [15] also discussed the existence of a fatigue limit for metals. Miller et al [6] also discussed the fatigue limit and methods for overcoming it.…”

Section: Introductionmentioning

confidence: 99%

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High-Cycle Microscopic Severe Corrosion Fatigue Behavior and Life Prediction of 25CrMo Steel Used in Railway Axles

Wang

et al. 2017

Metals

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Abstract:The effects of environmental media on the corrosion fatigue fracture behavior of 25CrMo steel were investigated. The media include air, and 3.5 wt % and 5.0 wt % NaCl solutions. Experimental results indicate that the media induces the initiation of corrosion fatigue cracks at multiple sites. The multi-cracking sites cause changes in the crack growth directions, the crack growth rate during the coupling action of the media, and the stress amplitude. The coupling effects are important for engineering applications and research. The probability and predictions of the corrosion fatigue characteristic life can be estimated using the three-parameter Weibull distribution function.

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Section: Introductionsupporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

High-Cycle Microscopic Severe Corrosion Fatigue Behavior and Life Prediction of 25CrMo Steel Used in Railway Axles

Wang

et al. 2017

Metals

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“…However, since K max includes a mechanical-and (predominantly tensile) thermal-residual stress contribution, arc-welded joint threshold values would be violated in almost any sea state. Though, question is whether threshold values truly exist as a constant, at least for metallic materials (Pyttel et al 2011;Bathias 2014). Well established crack growth threshold values seem to be in contrast to experimental data and is considered to be an important reason to prevent for formulations like the (extended) McEvily model, explicitly involving a threshold parameter as material constant.…”

Section: Crack Tip Stress Intensity Criterionmentioning

confidence: 99%

Fatigue damage criteria classification, modelling developments and trends for welded joints in marine structures

Besten

2018

Ships and Offshore Structures

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Fatigue is typically a governing limit state for marine structures. Welded joints are the weakest links in that respect. Physics involve several resistance dimensions, a range of scales and distinct contributions in different stages of the accumulative damage process. Fatigue damage criteria developed over time have been classified with respect to type of information, geometry, parameter and process zone including plane and life region annotations. The criteria are evaluated regarding model (in)capabilities, showing up to what extent (governing) physics are taken into account. Modelling developments and trends towards complete strength, multi-scale and total life criteria have been identified. Incorporating all four (interacting) fatigue resistance dimensions: material, geometry, loading & response and environment translates into a complete strength fatigue damage criterion. Considering macro-, meso-and micro-scale information provides a multi-scale fatigue damage criterion. Correlation of crack initiation and growth requires matching intact and cracked geometry parameters, revealing a total life fatigue damage criterion. HIGHLIGHTS• Classification of fatigue damage criteria with respect to type of information, geometry, parameter and process zone including plane and life region annotations.• Identification of modelling developments and trends towards complete strength, multi-scale and total life fatigue damage criteria for welded joints in marine structures. NomenclatureA notch strain energy density process zone area C crack growth or fatigue resistance curve intercept (endurance coefficient) D fatigue damage E normal strain at macro-scale E Young's modulus J crack tip energy density J 1 hydrostatic stress or strain component J 2 deviatoric stress or strain component K σ crack tip stress intensity factor K ɛ crack tip strain intensity factor K' work hardening coefficient K N notch stress intensity factor K N I mode-I notch stress intensity factor K N III mode-III notch stress intensity factor K I mode-I stress intensity factor K I T total mode-I stress intensity factor K I r residual mode-I stress intensity factor K III mode-III stress intensity factor K * FE dimensionless FE based notch stress intensity factor N (total) number of cycles until failure N i number of cycles corresponding to initiation N g number of cycles corresponding to growth R notch strain energy density process zone radius S stress based fatigue damage criterion S B Battelle structural normal stress range S e effective notch stress range S eq (equivalent) Von Mises stress range S n nominal stress range S s hot spot structural stress range S T total stress range T temperature T B Battelle structural shear stress range T σS strength scatter band index W energy based fatigue damage criterion W N notch strain energy W N A notch strain energy density Y n notch factor Y f far field factor a crack size (i.e. length) a 0 critical defect size a d long-term corrosion pit size (i.e. depth) a i (real) defect or initial crack size a n (root) not...

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“…The geometrical and structural factors of welded joint has developed into a notch-based fatigue design approach [9], also termed local stress or strain approach [10,11], which, generally leads to costly over-design, has witnessed great effectiveness in both low cycle fatigue (LCF) and high cycle fatigue (HCF) regimes. It is generally accepted that there exists a transition of crack initiation modes from specimen surface in LCF and HCF regimes to interior micro-defects in very high cycle fatigue (VHCF) regime which is characteristic of ultralong fatigue life (fatigue life higher than 10 7 cycles) under lower stress levels often below the traditional fatigue limit [12]. The change of the shape of S-N curves has attracted great interests in fatigue design [13,14].…”

Section: Introductionmentioning

confidence: 99%

Failure mechanisms and fatigue strength reduction factor of a Cr-Ni-Mo-V steel welded joint up to ultra-long life regime

Zhu

Xuan

2018

MATEC Web Conf.

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Abstract. It is known that welded joint is much "weaker" than base metal due to discontinuities of geometry, materials and residual stresses. It seems current international design rules do not adopt a uniform approach to weld efficiency, which is often defined as the ratio of the strength of a welded joint to the strength of base metal, in their guidance for creep and fatigue design of welds. This appears to be a great barrier for the application of nuclear welded structures which has a prolonged design lifetime of 60 years. In this work, fatigue strength reduction factor of a Cr-Ni-Mo-V steel welded joint, machined from welded steam turbine rotors for nuclear power plant, was investigated by performing axially push-pull cyclic loads tests with both cross-weld and pure base metal specimens up to very high cycle fatigue regime under ultrasonic frequency at ambient temperature. The effects of residual stress, strain localization, and microdefects in mismatched steels on failure mechanisms of welds were discussed thoroughly. Results show that fatigue strength reduction factor is varied in the range of 0.95-0.975, and is found to be dependent on fatigue lifetime for the first time. It is indicated that variation of fatigue strength reduction factor are associated with transition of crack initiation from specimen surface in high cycle fatigue regime to interior micro-defects in very high cycle fatigue regime. Comparing existing codes and standards for fatigue design of welds with experimental data indicates the over-conservativeness of present code-based design method. This implies a micro-defect based fatigue design approach is required for long life safe and reliability of weldments.

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Very high cycle fatigue – Is there a fatigue limit?

Cited by 250 publications

References 26 publications

High-Cycle Microscopic Severe Corrosion Fatigue Behavior and Life Prediction of 25CrMo Steel Used in Railway Axles

High-Cycle Microscopic Severe Corrosion Fatigue Behavior and Life Prediction of 25CrMo Steel Used in Railway Axles

Fatigue damage criteria classification, modelling developments and trends for welded joints in marine structures

Failure mechanisms and fatigue strength reduction factor of a Cr-Ni-Mo-V steel welded joint up to ultra-long life regime

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