Session: 09-01-17 Wind Energy: Structures 2

Paper Number: 126342

126342 - Simplified Fatigue Load Cases Assessment in Floating Offshore Wind Structural Analysis 

The estimation of fatigue lifetime for a floating offshore wind turbine (OWT) support structure requires a significant amount of simulation time. It is important to reduce the number of load cases while retaining high fidelity of the results. The most challenge part is to feasibly represent applied stochastic input loading from wind turbine components and environmental excitations simultaneously based on the co- occurrence probability.

The design processes on floating support structures of OWTs so far have been based on the experience coming from both wind turbine designers and offshore structure designers. Rotor-nacelle assemblies and corresponding towers are typically mass produced by wind turbine manufacturers. For modern OWT is well designed with complicated control strategies to consider hydrodynamic coupling effect of the flexibility of floating support structures, there is a unique load case for each wind speed at both operational and parked conditions. However, for offshore structures design against fatigue, loads must be defined over all loading from OWT components and environmental excitations, and then summed over the distribution of input conditions weighted by the relative annual occurrence of wind and wave.

Given that cut-in wind speed of 3 m/s and cut-out wind speed of 25 m/s, we take a wind speed bin of 2 m/s for all integer wind speed seeds, the processing of fatigue in time domain includes over 4000 simulation cases, and each simulation case would take 60 min for a continuous analysis length (also with another 6 random hydrodynamic transient seeds). As a consequence, to calculate one OWT operational wind speed including the median peak spectral period associated with each significant wave length at site, the whole computation quantity is numerous, not to mention the wind-wave misalignment. The trade-off approach of complete fatigue load cases simplification so far has been indistinct on the assessment of objectives. We present a novel method for simplified fatigue load cases based on statistical regression model which optimizes the wind speed seeds during power production. The main concept is predicting the exceedance probability of the loading of wind turbine components to decide the proper wind speed bin. We demonstrate the method for a semi-submissible support structure. The viable reducing number of simulated load cases exhibited a maximum error up to 10% comparing with that of the assessment of the objective fatigue lifetime under different grouping levels. By using such methods, the computational cost for the fatigue lifetime estimation of a structural design can be reduced significantly. It is promising in the application of structural optimization which needs a large number of iterations.

Presenting Author: Xun Meng Ocean University of China

Presenting Author Biography: Name: XUN MENG
Department: Ocean Engineering Department
Address: No. 2-305B, Engineering College, Ocean University of China, No.238 Songling Road, Qingdao,
P. R. China, 266100
Cell Phone: +86-18669835528
E-mail: mengxun@ouc.edu.cn
Education:
1. 2006/09–2010/06, Ocean University of China. Harbor, Coastal and Offshore Engineering, Ph.D.
2. 1996/09–1999/06, QingDao University of Technology, Applied Mechanics, Master Degree.
3. 1992/09–1996/06, QingDao University of Technology, Civil Engineering, Bachelor Degree.
Work Experience:
1. 1999.07 –Now, Work in, Engineering College, Ocean University of China
2. 2023.06-2024.06, Visiting scholar, School of Engineering, Computing and Mathematics. University of Plymouth.Funded China scholarship council (CSC).
3. 2015.08-2016.08, Visiting scholar, Australia Joint Research Centre for Building Information Modelling, School of Built Environment, Curtin University, Perth, Australia. BIM Applications in Ocean Engineering Field. Funded by Curtin University &BIM center.
4. 2010.08- 2011.07, Post-doctorates mobility of TANDEM Alliance program, Universidad Politécnica de Madrid (UPM), Madrid, Spain. Fiber-metal Hybrid Laminates Used on Towers of Offshore Wind Turbines. Funded by ERASMUS.
5. 2005.03-2005.09, Visiting scholar, University of California, San Diego (UCSD), California, USA. Teaching Sciences in English-Faculty Development Program, Engineering Mechanics, Funded China scholarship council (CSC).
Research Interests / responsibilities:
1. Dynamic coupling analysis and failure mechanism study on kinematics and dynamics of the offshore multi-body system;
2. Virtual prototype technology R & D and multi-criteria evaluation of the comprehensive performance for offshore engineering equipment;
Courses:
1. Undergraduate student courses： 《Offshore Platforms Design》、《Offshore Pipelines Design》、《Engineering Mechanics》、《Reinforced Concrete Structures》、《Composite Structures》、《Theoretical Mechanics》、《Material Mechanics》、《Engineering Graphing》、《Professional English（Civil Engineering）》、《ANSYS-Structural Design》
2. Graduated student course：《Professional English（Harbor, Coastal and Offshore Engineering）》
Research Projects:
Responsible：
1. Correlation study of the floating multi-body system on fluid-structure interaction at near field and multi-body motions, 2021/01-2024/12, the National Natural Science Foundation of China（52071307）
2. Research on dynamic characteristics and comprehensive evaluation technology of marine urban complex,2020/10-2023/10, Sub project of key R & D plan of Shandong Province (major scientific and technological innovation project) in 2020
3. Parametric design of key structure area, 2020/05-2021/05, technological service
4. Virtual R & D and process visualization of offshore engineering equipment, 2019/01-2019/12, Construction project of key disciplines for serving Qingdao's industrial development（2019KJG001）
5. Research on fast strength analysis technology for main structures of deepwater drilling platforms, 2017/10-2018/10, technological service
6. Study on key technologies and multi-criteria decision making of a new-type floating support with large-MW OWT at deeper water,2014/01-2016/12, the National Natural Science Foundation of China（51309209）
7. Research on uneven settlement of foundation for super large pipe gallery in non-slide area, 2014/01-2014/12, technological service
……
Participant:
1. The couplings among multi-oceanic fields, multi-body and multi-scale，and their effects on the performance and safety of ocean engineering equipment, 2021/01-2025/12, the National Natural Science Foundation of China-Fundamental science centre（52088102）
2. Hydrodynamic theory and analysis methods for fluid and structure interactions of large scale deep-water floating structures，2015/01-2019/12，the National Natural Science Foundation of China-Major project（51490670）
3. Research on comprehensive utilization of marine energy in Shandong Province, 2018/01-2018/12, technological service
……
Representative Publication:
1. Shujie Zhao,Xun Meng,Zhen Gao,Huajun Li.Numerical modeling of nonstationary hydrodynamic forces and induced motions of a coupled offshore floating installation system. Ocean Engineering. 246 (2022) 110618
2. Shujie Zhao, Xun Meng, Huajun Li, Dejiang Li, Qiang Fu. Continuous multi-body dynamic analysis of float-over deck installation with rapid load transfer technique in open waters. Ocean Engineering. 224(2021)108729
3. Shujie Zhao, Zhen Gao, Dejiang Li, Xun Meng. DYNAMIC PROPERTY OF A FLOATING MULTI-BODY SYSTEM FOR DUAL BARGE FLOAT-OVER OPERATION WITH A MECHANICAL TLS (TOPSIDE LIFTING SYSTEM). OMAE2022-78400.
4. Xun MENG, Xingqi DENG, Shujie ZHAO, Dejiang LI, Qiang FU. ROLL STABILITY EVALUATION OF THE FLOATING MULTI-BODY SYSTEM AT TML (TWIN MARINE LIFTER) OPERATION. OMAE2022-79871
5. Xun MENG,Pin TANG,Dejiang LI,Yu XU, Qiang FU. Optimization-based Multi-attribute Decision Making for the 7th Generation Semi-submersible Drilling Unit. In: Proceedings of the 39th International Conference on Offshore Mechanics and Arctic Engineering, OMAE 2020, June 28-July 3, Fort Lauderdale, FL, USA.
6. TANG, Xun MENG, Dejiang LI, Harmonic Oscillations Study on Hull Motion and Payload Pendulation of the Offshore Large Crane Vessel, ISOPE PACOMS 2020: 14th ISOPE Pacific/Asia Offshore Mechanics Symposium, Dalian, China
7. Meng Xun*,Shi Ruifeng,Multi-criteria assessment of offshore wind turbine support structures based on dynamic property optimization，High Technology Letters，2014,20(4):421-428.
8. Meng Xun*,Geng Aoxiang,Li Xin,Multi-criteria-decision-making of floating supports with large-capacity OWT at deep water,2014 International Conference on Advanced Nano-Technology and Biomedical Material,ANTBM 2014,484-491,2014.6.28-2014.6.30.
9．Meng Xun*,Lou Qi,Shi Ruifeng,Multi-criteria-decision-making of a TLP support with large - capacity OWT at deep water,24th International Ocean and Polar Engineering Conference, ISOPE 2014 Busan,384-389,2014.6.15-2014.6.20.
10. Gong Chen,Meng Xun* ,Gao Renjie,Shan Jihua,Li Fengjian,Sun Longlong, Bearing capacity analysis of the slab of slipways at marine engineering construction site,2014 International Conference on Green Materials and Environmental Engineering, GMEE,2014,715-720, 2014.9.18-2014.9.20.
11. Shi Ruifeng,Meng Xun*,Numerical simulation and structural analysis of oceanic oil containment booms in towing condition,24th International Ocean and Polar Engineering Conference, ISOPE 2014 Busan,597-604,2014.6.15-2014.6.20
12. Meng Xun*, S.de Guzman,M.A.Herreros, I.Diez de Ulzur, Materiales híbridos estructurales fibra-metal para aerogeneradores offshore, The Spanish Conference in Composite Materials at Gerona, 2011.08.13-2011.08.15.
13.Yang Min, Meng Xun*.Response characteristics analysis of vortex-induced motions of deep draft semi-submersible platform using SST-IDDES. Chinese Journal of Hydrodynamics. 34(2). 2019: 238-247
14.Yu Yulian, Gou Hongshun,Xing Qixian,Meng Xun*.Unsteady dynamic response analysis of Spar wind turbine.Journal of waterway and harbor. 40(6),2019: 694-699
15. Meng Xun*,Tian Huiyuan,Li Xin,MULTI-CRITERIA-DECISION-MAKING OF FOWT BASED ON DYNAMIC PROPERTY, ACTA ENERGIAE SOLARIS SINICA, 2016, 37(8):2063-2067
16. Meng Xun*, Hou Jinlin, Yu Chunjie, Huang Weiping, Li Huajun.Quasi-statistic Analysis of a Monopile Supported OWT structure[J]. Journal of Ocean of University of China (Natural Science). Vol.40,2010. (in Chinese)
17. Meng Xun*, LI Huajun,Bao Xingxian. Feasible Study on Oil Jacket Platforms in Supporting Structural Systems of OWTs[J].Journal of Basic Science and Engineering. Vol. 18, No. 4, 2010. pp626-636. (in Chinese)
18. Meng Xun, Optimum Technology on Support Structures of Offshore Wind Turbine Based on Dynamic Properties, PHD thesis, Ocean University of China, 2016. (in Chinese)

Authors:

Xun Meng Ocean University of China
Zhao Yue Wang Ocean University of China
Lu Qing University of Plymouth, Ocean University of China
Robert Rawlinson Smith University of Plymouth
Deborah Greaves University of Plymouth
Wenping Wang Shenzhen Intelligent Ocean Engineering Innovation Center Limited; Yantai CIMC Ocean Engineering Co., ltd.
Qiang Fu Shenzhen Intelligent Ocean Engineering Innovation Center Limited, Yantai CIMC Ocean Engineering Co., ltd.