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| Vortex induced vibration and fatigue damage of risers with two-degrees-of-freedom considering different frequency ratios |
| Tang Shi-zhen; Huang Wei-ping; LIU Jian-jun; DENG Yue |
| The key Ocean Engineering laboratory of Shandong province, University of China,Qingdao,266100,China |
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Abstract The variation of response amplitude and fatigue damage of riser with two-degrees-of- freedom is proposed, considering four kinds of different frequency ratios (drag force frequency/lift force frequency). The results show that under a low frequency ratio and low reduced velocity, the in-line vibration will restrain the cross-flow vibration. And also with the 6.3< reduced velocity <8.0, the cross-flow amplitude will increase clearly considering the in-line vibration. With the increase of frequency ratio, the effect will be weakened. The cross-flow vibration influences the in-line vibration severely in all the cases. The in-line amplitude will increase evidently. The fatigue damage with two degrees is great lager than that with one degree with low frequency ratio. The fatigue in in-line direction is inclined to be influenced by the cross-flow vibration with a high frequency ratio.
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Received: 01 January 1900
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Corresponding Authors:
Tang Shi-zhen
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2011, Vol. 30 
