DOI QR코드

DOI QR Code

Nonlinear Finite Element Analysis for Mooring Chain Considering OPB/IPB

OPB/IPB를 고려한 계류체인의 비선형 수치해석

  • Kim, Min-suk (Department of Naval Architecture and Ocean Engineering, Inha University) ;
  • Kim, Yooil (Department of Naval Architecture and Ocean Engineering, Inha University)
  • 김민석 (인하대학교 조선해양공학과) ;
  • 김유일 (인하대학교 조선해양공학과)
  • Received : 2017.01.16
  • Accepted : 2017.06.22
  • Published : 2017.08.31

Abstract

The design of the mooring line to maintain the position of an offshore structure in rough marine environments is recognized as a very important consideration. Conventional fatigue evaluation of a mooring line was performed by considering the tensile force acting on the mooring line, but the mooring line broke after 238 days in the girassol area even though the expected fatigue life was expected to be longer. The causes of this event are known to be due to OPB/IPB (out-of-plane bending/in-plane bending) caused by chain link friction due to the excessive tensile strength of the mooring line. In this study, three models with different boundary conditions were proposed for fatigue analysis of a mooring line considering OPB/IPB. Interlink stiffness was calculated by nonlinear structure analysis and a stress concentration factor was derived. In addition, the sensitivity of interlink stiffness according to the magnitude of tensile force, large deformation effect, and coefficient of friction was analyzed, and the effect of critical elastic slip and bending moment calculation position on interlink stiffness was confirmed.

Keywords

Out-of-plane bending;In-plane bending;Interlink stiffness;Stress concentration factor;Critical elastic slip

References

  1. Bureau Veritas, 2014. Fatigue of Top Chain of Mooring Lines Due to In-plane and Out-of-plane Bendings. Guidance Note NI 604 DT R00 E.
  2. Choung, J., Han, S., 2016. A Novel Procedure for Mooring Chain Fatigue Prediction Based on Maximum Principal Stress Considering Out-of-plane and In-plane Bending Effect. Journal of the Society of Naval Architecture of Korea, 53(3), 237-248. https://doi.org/10.3744/SNAK.2016.53.3.237
  3. Hwang, O.J., 2012. Fatigue Assessment of Mooring Chain Link of Spread-moored FPSO in Deepwater Considering Bending Shenomenon. Ph.D., Dissertation, Korea Maritime and Ocean University.
  4. Lim, Y., Kim, K., Choung, J., Kang, C., 2010. A Study on Out-of-Plane Bending Mechanism of Mooring Chains for Floating Offshore Plants. Journal of the Society of Naval Architects of Korea, 47(4), 580-588. https://doi.org/10.3744/SNAK.2010.47.4.580
  5. Melis, C., Jean, P., Vargas, P.M., 2005. Out-of-Plane Bending Testing of Chain Links. Proceedings of 24th International Conference on Offshore Mechanics and Arctic Engineering, Halkidiki, Greece.
  6. Ramberg, W., Osgood, W., 1943. Description of Stress-Strain Curves by Three Parameters. National Advisory Committee for Aeronautics, Technical Note No. 902.
  7. Rampi, L., Bignonnet, A., Le Cunff, C., Bourgin, F., Vargas, P., 2016a. Chain Out of Plane Bending(OPB) Fatigue Joint Industry Project(JIP) FEA Results and Multiaxiality Study Results. Proceedings of 35th International Conference on Offshore Mechanics and Arctic Engineering, Busan, Korea.
  8. Rampi, L., Gerthoffert, A., Francois, M., Bignonnet, A., Vargas, P., 2016b. Chain Out of Plane Bending(OPB) Fatigue Joint Industry Porject(JIP) Fatigue Test Program Results and Methodology. Proceedings of 35th International Conference on Offshore Mechanics and Arctic Engineering, Busan, Korea.
  9. Vargas, P.M, Jean, P., 2005. FEA of Out-of-Plane Fatigue Mechanism of Chain Links. Proceedings of 24th International Conference on Offshore Mechanics and Arctic Engineering, Halkidiki, Greece.