Flexible riser tensile armour stress assessment in the bend stiffener region

Lu, Hailong; Vaz, Murilo Augusto; Caire, Marcelo

doi:10.1016/j.engstruct.2022.113849

Cited by 5 publications

(3 citation statements)

References 25 publications

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“…Therefore, the fatigue of the armour wire is mainly concerned in this paper. Some engineering experiences and previous research works 8,9 support above viewpoint.…”

Section: Methodologies 11 Bending Behaviors and Assumptionssupporting

confidence: 59%

“…This slip mechanism leads to a hysteretic bending moment-curvature relationship 5 , making it difficult to simulate the nonlinear bending stiffness or damping effects in global analysis, and meanwhile difficult to predict the bending stress for local analysis. In addition, it is well known the alternative bending stress generally contributes a major part to the fatigue damage for such structures [6][7][8][9] . Therefore, accurate models for bending stiffness and stress are both essential for the fatigue life prediction of a dynamic cable.…”

Section: Introductionmentioning

confidence: 99%

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Fatigue life prediction of a dynamic optical cable under a turret-moored FPSO

Xu,

Chen,

Shen

et al. 2024

Advanced Fiber Laser Conference (AFL2023)

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This paper presents an investigation of the fatigue life prediction for a dynamic optical cable under a turret-moored FPSO. The commonly used linear model for cable bending behaviors may lead to significant deviations or even mistakes in predicting the fatigue lives of optical cables. Therefore, three types of theoretical models are utilized to simulate the cable bending stiffnesses and stresses, which are introduced respectively into a case study of fatigue analysis. These models are no-slip, full-slip and bilinear, based on different assumptions on the friction effects between the armour wire layers. The difference in the predicted fatigue lives can reach five orders of magnitude, based on the above three models. It indicates that using different models to predict fatigue life may lead to overly conservative or overly risky conclusions, which can have a significant impact on design decisions. Finally, the bilinear bending model is recommended for the fatigue analysis of dynamic optical cables in similar floating systems.

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“…Therefore, the fatigue of the armour wire is mainly concerned in this paper. Some engineering experiences and previous research works 8,9 support above viewpoint.…”

Section: Methodologies 11 Bending Behaviors and Assumptionssupporting

confidence: 59%

Section: Introductionmentioning

confidence: 99%

Fatigue life prediction of a dynamic optical cable under a turret-moored FPSO

Xu,

Chen,

Shen

et al. 2024

Advanced Fiber Laser Conference (AFL2023)

View full text Add to dashboard Cite

show abstract

“…The study analyzed the impact of significant wave height and top tension coefficient on the fatigue life of experimental risers. Lu and Vaz et al [16] established a nonlinear finite element model for flexible risers with bend stiffeners. They conducted case studies on typical limit and fatigue load scenarios to assess the influence of curvature changes and bend stiffener contact pressure on the stress in the riser armor layer.…”

Section: Introductionmentioning

confidence: 99%

Simulation Study on Methods for Reducing Dynamic Cable Curvature in Floating Wind Power Platforms

Guo,

Zhao,

et al. 2024

JMSE

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As a key component connecting a floating wind turbine with static sea cables, dynamic cables undergo significant tensile and bending loads caused by hydrostatic pressure, self-weight, waves, and ocean currents during service, which can lead to fatigue failure. Thus, dynamic and fatigue analyses are necessary for the design and operation of dynamic cables. In this study, a fatigue analysis of the three-core four-layer armored dynamic cable used in a semisubmersible floating wind turbine was carried out at a water depth of 25 m. The Miner linear cumulative damage method, based on material S-N curves, was used to predict fatigue life. The results indicate that, at 10 times the safety factor, the dynamic cables meet the design requirement of a 30-year service life in the studied marine environment. The maximal curvature of the dynamic cable always appears at the exit of the bend stiffener, even beyond the allowed point. Adding weights to the section where the cable exits the bend stiffener and adjusting the bend stiffener’s hanging angle can both reduce the curvature at the bend stiffener exit. The scheme of adjusting the bend stiffener’s hanging angle is preferred, for it is easier for simultaneous adjusting and inducing much smaller extra stress in the cable. As the hanging angle increases, the curvature at the bend stiffener exit decreases, while the maximal effective tension and maximal von Mises stress gradually increase. For certain operating conditions, especially with higher waves, it is better to adjust the hanging angle to avoid excessive curvature and, meanwhile, ensure the increase in the stress within a reasonable range.

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