上海交通大学学报(英文版) ›› 2013, Vol. 18 ›› Issue (4): 493-499.doi: 10.1007/s12204-013-1425-y

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Computationally Efficient Approaches to Fatigue Analysis of Deepwater Risers

(School of Naval Architecture, Dalian University of Technology, Dalian 116024, Liaoning, China)   

  1. (School of Naval Architecture, Dalian University of Technology, Dalian 116024, Liaoning, China)
  • 出版日期:2013-08-28 发布日期:2013-08-12
  • 通讯作者: DONG Lei-lei (董磊磊) E-mail:andydong1027@mail.dlut.edu.cn

Computationally Efficient Approaches to Fatigue Analysis of Deepwater Risers

(School of Naval Architecture, Dalian University of Technology, Dalian 116024, Liaoning, China)   

  1. (School of Naval Architecture, Dalian University of Technology, Dalian 116024, Liaoning, China)
  • Online:2013-08-28 Published:2013-08-12
  • Contact: DONG Lei-lei (董磊磊) E-mail:andydong1027@mail.dlut.edu.cn

摘要: Riser long-term fatigue performance is an important design consideration. Although extensive application of irregular sea analysis in time domain with the rainflow counting technique for post-processing is regarded as the most accurate of the approaches for fatigue analysis, it does suffer from some limitations, such as the computational effort. For this reason, two computationally efficient approaches are employed to perform the fatigue analysis of a deepwater top-tensioned riser, based on the Longuet-Higgins distribution and time domain scaling respectively. With Longuet-Higgins distribution irregular wave sea states are expanded into their individual wave bins. These regular wave simulations are of short duration and consequently run quickly. Using the time domain scaling technique, the number of irregular wave runs can be performed for a comparatively small number of load cases and hence reduces the calculation time. The results showed a reasonable accuracy and significant efficiency for both approaches, compared with those from the equivalent rainflow analysis. With much less computational effort and disk storage requirement, the approaches outlined in this paper can therefore be used for the fatigue assessment of deepwater risers in industry practice.

关键词: Longuet-Higgins distribution, time domain scaling, deepwater riser, fatigue analysis

Abstract: Riser long-term fatigue performance is an important design consideration. Although extensive application of irregular sea analysis in time domain with the rainflow counting technique for post-processing is regarded as the most accurate of the approaches for fatigue analysis, it does suffer from some limitations, such as the computational effort. For this reason, two computationally efficient approaches are employed to perform the fatigue analysis of a deepwater top-tensioned riser, based on the Longuet-Higgins distribution and time domain scaling respectively. With Longuet-Higgins distribution irregular wave sea states are expanded into their individual wave bins. These regular wave simulations are of short duration and consequently run quickly. Using the time domain scaling technique, the number of irregular wave runs can be performed for a comparatively small number of load cases and hence reduces the calculation time. The results showed a reasonable accuracy and significant efficiency for both approaches, compared with those from the equivalent rainflow analysis. With much less computational effort and disk storage requirement, the approaches outlined in this paper can therefore be used for the fatigue assessment of deepwater risers in industry practice.

Key words: Longuet-Higgins distribution, time domain scaling, deepwater riser, fatigue analysis

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