A two-scale probabilistic time-dependent fatigue model for offshore steel wind turbines

Rocher, Benjamin; Schoefs, Franck; François, Marc; Salou, Arnaud; Caouissin, Anne-Laure

doi:10.1016/j.ijfatigue.2020.105620

Cited by 11 publications

(19 citation statements)

References 18 publications

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“…Consequently, the physical quantity Z in Equation ( 31) can be replaced by the fatigue damage state function G(n). According to Equation (29), the G(n) is a function related to the number of cycles n, which will increase gradually and continuously from zero as the load cycle increases. Thus, the time t in Equation ( 31) can be replaced by n due to its monotone increasing property.…”

Section: Probability Density Evolution Equationmentioning

confidence: 99%

“…27 This is mainly due to the fact that most state functions used in PDEM are established by the Miner model, which cannot consider nonlinear characteristic of the fatigue damage and loading history. 28,29 To deal with aforementioned problems, an improved Y-W model is proposed in this study, and the fatigue state function using the improved model is evaluated by the PDEM. To improve the Y-W model, a square ratio of load stress amplitudes is introduced into the original Y-W model to consider the load interaction effect under the multilevel load case.…”

Section: Introductionmentioning

confidence: 99%

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Nonlinear time‐varying fatigue reliability analysis based on the improved toughness exhaustion model

Gao

Liu

2021

Fatigue Fract Eng Mat Struct

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The state function based on fatigue accumulation model has a great influence on accuracy of fatigue reliability analysis of components. A nonlinear fatigue accumulation model considering the interaction of loads is proposed in this paper. The square ratio of front and back loads is presented as a new load interaction factor and embedded into the conventional toughness exhaustion model; thus, this improved model can reflect the load sequence and interaction effect simultaneously. Moreover, the fatigue state function using the improved model is constructed and analyzed by the probability density evolution method. Then experimental data of four materials are used to verify the proposed model, and results show that the residual life fraction predicted by the proposed model is accurate. Furthermore, accuracy and efficiency of the timevarying fatigue reliability analysis using the proposed model is validated using experimental data from a carbon steel test and a helical compression spring test.

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Section: Probability Density Evolution Equationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Nonlinear time‐varying fatigue reliability analysis based on the improved toughness exhaustion model

Gao

Liu

2021

Fatigue Fract Eng Mat Struct

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“…A probability distribution fit to observed data can often be a meaningful marker [59][60][61] for assessing various changes of damage conditions as compared to individual comparison of percentiles. Multiple distributions were considered for this data in this regard.…”

Section: Probability Distribution Fits For Acceleration Responsesmentioning

confidence: 99%

Damage Monitoring of a Catenary Moored Spar Platform for Renewable Energy Devices

2020

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Structural performance of renewable energy device platforms is central to their power generation in a reliable and competitive manner. However, there is a gap in research in the conceptual and experimental stages of such devices at lower technological readiness levels in terms of understanding of their structural responses. Uncertainties around knowledge related to damage conditions of such structures are under-researched and experimental investigations into the monitoring of performance of such structures are significantly needed. This research addresses this need and investigates various damage conditions in a scaled catenary moored spar platform in an ocean wave basin, exposed to typical wave conditions for the west coast of Ireland. A comparison of the monitored structural responses was carried out with respect to the undamaged experimental model. It was observed that while free decay tests were not useful to distinguish between various damage levels, a characterisation of the distribution of the responses can be relevant in identifying damages or significant structural changes. The work contributes to the much-needed experimental evidence base around structural health monitoring of renewable energy device platforms.

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“…It is assumed that compression doesn't influence crack propagation but since welded joints contain residual stresses, all the stress spectrums must be considered [4]. The crack propagation can be divided into three stages: the first is characterized by considerable low crack growth rates and in this region can be identified a value, known as the threshold, above which there is no crack growth; the second stage is the region known as "Paris region", because the crack growth as a function of stress intensity can be defined by the following expression, which was proposed by Paul Paris: (16) where: da/dN is the fatigue crack growth rate; C and m are constants obtained through experimental tests; and ΔK is the stress intensity factor range (ΔΚ=Kmax-Kmin). The stress intensity factor, K, can be expressed as:…”

Section: Fracture Mechanics Approachmentioning

confidence: 99%

“…Horn and Leira [15] investigated the impact on the estimated life of an offshore wind turbine through the introduction of a stochastic model. An incremental damage model of two scales was proposed by Rocher [16], in order to follow the temporal evolution of the damage caused by fatigue. Fatigue assessments of offshore wind turbine support structures have also been proposed in the literature considering realistic environmental conditions [17], economic-tracking NMPC [18], and a parallel scheme [19].…”

Section: Introductionmentioning

confidence: 99%

A brief review of fatigue design criteria on offshore wind turbine support structures

Mendes

Correia

Jesus

et al. 2020

Frattura Ed Integrità Strutturale

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In this paper, a brief review of the main fatigue design criteria and some advanced fatigue approaches applied to offshore structures (e.g. offshore wind turbines) are presented. It is extremely important to understand the fatigue phenomenon and how it affects structures since offshore structures are constantly submitted to cyclic loading and corrosive attacks that aggravate the problem. All the influencing factors and approaches used during the design phase are also discussed.

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A two-scale probabilistic time-dependent fatigue model for offshore steel wind turbines

Cited by 11 publications

References 18 publications

Nonlinear time‐varying fatigue reliability analysis based on the improved toughness exhaustion model

Nonlinear time‐varying fatigue reliability analysis based on the improved toughness exhaustion model

Damage Monitoring of a Catenary Moored Spar Platform for Renewable Energy Devices

A brief review of fatigue design criteria on offshore wind turbine support structures

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