파랑하중에 의한 Steel Catenary Riser 피로손상 평가 방법의 비교검토
Comparative Study on Wave Induced Fatigue Analysis Methods for Steel Catenary Riser
0
조회
0
다운로드
0
인용
0
참고문헌
키워드
초록
The purpose of this study is to suggest guidelines for riser fatigue analysis in terms of selection of reasonable analysis method. Three analysis methods (spectral, regular wave, rain-flow counting) are introduced and compared. As the riser systems give non-linear response, the time-domain analysis method is more preferred than frequency-domain analysis method. The spectral fatigue analysis method, however, is still useful for identifying fatigue prone areas. Once stress RAO is established, fatigue damage can be calculated very quickly. The regular wave method and the rain-flow counting method are more time consuming but give more exact results compare to spectral method. In case of regular wave method, a set of regular waves which represent random sea states is considered for dynamic analysis. The rain-flow counting method is the most intuitive and exact method because it refers time history stresses containing most of non-linear effects of the riser system. However, it is not common for early design stage to use rain-flow counting method because of its high cost. In this study, it was confirmed that the regular wave method is the most cost effective way in specific cases. However, if the system is highly non-linear, it seems that the regular wave method gives less accurate results than rain-flow counting method. Therefore, it is imperative that the engineers select appropriate analysis method based on design stage and given engineering period. This paper also discusses the theoretical background of each calculation method and hydrodynamic aspects of marine riser systems. A steel catenary riser (SCR) line on FPSO was considered and marine dynamic program (OrcaFlex) was used for static and dynamic analysis.
Abstract
The purpose of this study is to suggest guidelines for riser fatigue analysis in terms of selection of reasonable analysis method. Three analysis methods (spectral, regular wave, rain-flow counting) are introduced and compared. As the riser systems give non-linear response, the time-domain analysis method is more preferred than frequency-domain analysis method. The spectral fatigue analysis method, however, is still useful for identifying fatigue prone areas. Once stress RAO is established, fatigue damage can be calculated very quickly. The regular wave method and the rain-flow counting method are more time consuming but give more exact results compare to spectral method. In case of regular wave method, a set of regular waves which represent random sea states is considered for dynamic analysis. The rain-flow counting method is the most intuitive and exact method because it refers time history stresses containing most of non-linear effects of the riser system. However, it is not common for early design stage to use rain-flow counting method because of its high cost. In this study, it was confirmed that the regular wave method is the most cost effective way in specific cases. However, if the system is highly non-linear, it seems that the regular wave method gives less accurate results than rain-flow counting method. Therefore, it is imperative that the engineers select appropriate analysis method based on design stage and given engineering period. This paper also discusses the theoretical background of each calculation method and hydrodynamic aspects of marine riser systems. A steel catenary riser (SCR) line on FPSO was considered and marine dynamic program (OrcaFlex) was used for static and dynamic analysis.
참고문헌 (15)
- Almar-Naess, "Fatigue Handbook Offshore Steel Structure" (1985), Tapir Publishers
- Design of Risers for Floating Production Systems (FPSs) and Tension-Leg Platform(TLPS), "API, Recommended Practice 2RD", API, ~ (2006)
- Braccesi, C., "Fatigue Behavior Analysis of Mechanical Components Subject to Random Bimodal Stress Process", International Journal of Fatigue, 27, pp.335~345 (2005)
- "The complexities of fatigue analysis for deepwater risers" (1999)[URL]
- Chakrabarti, S. K., "Hydrodynamics of Offshore Structures" (1987), Computational Mechanics Publications Southhampton
- DNV-Offshore Standard-F201, "Dynamic Risers", DNV, ~ (2010)
- DNV-Recommended Practice - C205, "Environmental Conditions and Environmental Loads", DNV, ~ (2010)
- Gonzalez, E. C., "Steel catenary riser design and analysis for petrobras roncador field dvelopment", Offshore Technology Conference (2005)
- Leverette, S., "Analysis of TLP VIV response to eddy currents", Offshore Technology Conference (2003)
- LI, Y., "Sensitivity of SCR fatigue at touch Down point : effect of marine growth", nternational Offshore and Polar Engineering Conference, pp.281~286 (2012)
- Longuet-Higgins, M. S., "On the Joint Distribution of Wave Periods and Amplitudes in a Random Wave Field", Proceedings Royal Society London, Series A, Mathematical and Physical Sciences, 389(1797) (1983)
- Luciano de A. Campos, "Nonlinear dynamic response of a steel catenary riser at the touch-down point", Proceedings of the Eleventh International Offshore and Polar Engineers Conference, pp.234~238 (2001)
- Orcina, "OrcaFlex Manual, Version 9.6a", Orcina, ~ (2014)
- Power, T.L., "Spectral and cycle-counting damage estimation methods for steel catenary risers", Offshore Technology Conference (2008)
- Ye, W., "Effects of fully coupled and quasi-static semi-submersible vessel motions on steel catenary riser’s wave loading fatigue", Offshore Technology Conference (2003)