Synergy of crack closure, near-tip residual stress and crack-tip blunting in crack growth under periodic overloads – A fractographic study

Sunder, R.; Biakov, A.; Еремин, А. В.; Panin, S. V.

doi:10.1016/j.ijfatigue.2016.08.004

Cited by 26 publications

(10 citation statements)

References 8 publications

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“…Rare large magnitudes loads, e.g., due to ice-structure interaction, are known to alter fatigue crack propagation by crack retardation or acceleration [29]. This effect is extensively studied for single or periodic load cycles; however, it is also known that events with a series of large cycles may affect crack propagation.…”

Section: Fatigue Design Of Offshore Wind Turbine Support Structures I...mentioning

confidence: 99%

Development of Combined Load Spectra for Offshore Structures Subjected to Wind, Wave, and Ice Loading

et al. 2022

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Fixed offshore wind turbines continue to be developed for high latitude areas where not only wind and wave loads need to be considered but also moving sea ice. Current rules and regulations for the design of fixed offshore structures in ice-covered waters do not adequately consider the effects of ice loading and its stochastic nature on the fatigue life of the structure. Ice crushing on such structures results in ice-induced vibrations, which can be represented by loading the structure using a variable-amplitude loading (VAL) sequence. Typical offshore load spectra are developed for wave and wind loading. Thus, a combined VAL spectrum is developed for wind, wave, and ice action. To this goal, numerical models are used to simulate the dynamic ice-, wind-, and wave-structure interaction. The stress time-history at an exemplarily selected critical point in an offshore wind energy monopile support structure is extracted from the model and translated into a VAL sequence, which can then be used as a loading sequence for the fatigue assessment or fatigue testing of welded joints of offshore wind turbine support structures. This study presents the approach to determine combined load spectra and standardized time series for wind, wave, and ice action.

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Section: Fatigue Design Of Offshore Wind Turbine Support Structures I...mentioning

confidence: 99%

Development of Combined Load Spectra for Offshore Structures Subjected to Wind, Wave, and Ice Loading

et al. 2022

View full text Add to dashboard Cite

show abstract

“…Rare large magnitudes loads, e.g., due to ice-structure interaction, are known to alter fatigue crack propagation by crack retardation or acceleration [29]. This effect is extensively studied for single or periodically load cycles; however, it is also known that events with a series of large cycles may affect crack propagation.…”

Section: Fatigue Design Of Offshore Wind Turbine Support Structures Including Ice Loading and Sub-zero Temperaturesmentioning

confidence: 99%

Development of Combined Load Spectra for Offshore Structures Subjected to Wind, Wave, and Ice Loading

Braun¹,

Dörner²,

Veer³

et al. 2021

Preprint

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Fixed offshore wind turbines continue to be developed for high latitude areas where not only wind and wave loads need to be considered, but also moving sea ice. Current rules and regulations for the design of fixed offshore structures in ice-covered waters do not adequately consider effects of ice loading and its stochastic nature on fatigue life of the structure. Ice crushing on such structures results in ice-induced vibrations, which can be represented by loading the structure using a variable-amplitude loading (VAL) sequence. Typical offshore load spectra are developed for wave and wind loading. Thus, a combined VAL spectrum is developed for wind, wave, and ice action. To this goal, numerical models are used to simulate the dynamic ice-, wind-, and wave-structure interaction. The stress time-history at an exemplarily selected critical point in an offshore wind energy monopile support structure is extracted from the model and translated into a VAL sequence, which can then be used as a loading sequence for the fatigue assessment or fatigue testing of welded joints of offshore wind turbine support structures. This study presents the approach to determine combined load spectra and standardized time series for wind, wave, and ice action.

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“…Furthermore, the variation in subsequent da/dN has also been studied by crack kinking, 19 small secondary cracks, 20 crack branching, 21 microstructure, 22 heterogeneity of the material, 23 shielding influence, 24,25 and their combined contributions. [26][27][28] By now, a little research has been designed to investigate the potential trends of the resulting variation in da/dN after a single tensile OL. The following questions also need to be considered carefully.…”

Section: Introductionmentioning

confidence: 99%

Trends in fatigue-crack growth for the 2024 Al-alloy after a single tensile overload

Zhang¹,

Lei²,

Liu³

et al. 2018

Mater. Tehnol.

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A single tensile overload (OL) applied during a constant amplitude fatigue test could have a positive or negative influence on improving the subsequent fatigue-crack growth rate (da/dN). The resulting variation in da/dN was very relevant to both the OL level and the fatigue loading conditions. Comprehensive tests on 2024-T4 Al-alloy specimens were carried out to rationalize the variation trend of da/dN after a single tensile OL. It was found that the trend of the fatigue-crack growth after the OL is not unique, but strongly depends on the OL stress-intensity factor KOL and the applied stress-intensity factor Kapp just before OL. Three potential trends of variation in da/dN, related to both the KOL and the KOL/Kapp ratio, were proposed in this study: initial deceleration and then recovery (Type I); initial slight-acceleration, subsequent retardation and final recovery (Type II); and initial major-acceleration, subsequent retardation and final recovery (Type III). Among the three types, the type II with the medium KOL/Kapp ratio and the low Kapp is the optimal OL type for improving the fatigue life of a 2024-T4 Al-alloy specimen. Keywords: overload, fatigue crack growth trend, fatigue retardation, overload-induced fracture zone Med testom utrujanja s konstantno amplitudo so uporabili posamezen natezni preizkus s preobremenitvijo (OL; angl.: single tensile overload) ter ugotovili, da ima lahko le-ta pozitiven ali negativen vpliv na nadaljnjo hitrost rasti razpoke (da/dN). Nastala razlika v da/dN je bila tesno povezana tako z nivojem OL kot tudi s pogoji utrujanja. Avtorji~lanka so izvedli ob{irne preizkuse na vzorcih Al zlitine 2024-T4, da bi razumeli trend variiranja da/dN po OL. Ugotovili so, da trend hitrosti rasti razpoke po OL ni enoten, temve~je mo~no odvisen od razmerja OL-faktor intenzitete napetosti KOL in uporabljenega nivoja napetostnega faktorja intenzitete Kapp tik pred OL. V tej {tudiji so avtorji predlagali tri mo`ne trende variiranja da/dN glede na KOL in razmerje KOL/Kapp: za~etno zmanj{evanje hitrost (zaviranje) in nato popravo (Type I); za~etno rahlo pospe{evanje, odla{anje in nato popravo (Type II) in za~etno izrazito pospe{evanje, kateremu je sledilo odla{anje in kon~na poprava (Type III). Med vsemi tremi je tip II s srednjim KOL/Kapp razmerjem in nizkim Kapp optimalen OL tip za izbolj{anje dobe trajanja vzorcev iz Al zlitine 2024-T4. Klju~ne besede: preobremenitev, trend rasti utrujenostne razpoke, odla{anje utrujanja, s preobremenitvijo inducirana cona loma

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Synergy of crack closure, near-tip residual stress and crack-tip blunting in crack growth under periodic overloads – A fractographic study

Cited by 26 publications

References 8 publications

Development of Combined Load Spectra for Offshore Structures Subjected to Wind, Wave, and Ice Loading

Development of Combined Load Spectra for Offshore Structures Subjected to Wind, Wave, and Ice Loading

Development of Combined Load Spectra for Offshore Structures Subjected to Wind, Wave, and Ice Loading

Trends in fatigue-crack growth for the 2024 Al-alloy after a single tensile overload

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