Parametric and External Excitation of Marine Risers
Parametric and External Excitation of Marine Risers
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DOI：
10.1061/(asce)0733-9399(1992)118:5(942
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发表时间：
1992-05
期刊：
影响因子：
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通讯作者：
S. Thampi;J. Niedzwecki
中科院分区：
文献类型：
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作者：
S. Thampi;J. Niedzwecki
利用马尔可夫方法研究了非线性海洋立管模型对参数激励和外部激励的响应。利用矩闭合技术预测立管在随机海浪中的响应。一个近似的非线性多项式表示的流体动力阻尼项的开发，以实现高斯和非高斯矩封闭计划。这些方法适用于解决纯参数激励的情况下，并与随机平均得到的结果进行了比较。结果表明，作为参数激励水平是不同的，从不同的技术的响应预测表现出相同的线性趋势。然而，非高斯封闭方案提供了更接近随机平均结果的改进的响应估计。力矩闭合技术，然后扩展到考虑参数和外部激励相结合的立管。对于一个固定的参数激励水平，响应统计被发现与外部激励水平的非线性变化。高斯封闭方案被发现过度预测结构响应的情况下，纯参数激励和低估结构响应的情况下，纯外部激励。
The response of a nonlinear marine riser model to both parametric and external excitation is examined using Markov methods. Moment-closure techniques are used to predict the response of the riser in a random seaway. An approximate nonlinear polynomial representation of the hydrodynamic damping term is developed in order to implement Gaussian and non-Gaussian moment-closure schemes. These methods are applied to solve the case of pure parametric excitation and the results are compared with those obtained using stochastic averaging. It is shown that as the parametric excitation level is varied, the response predictions from different techniques exhibit the same linear trends. However, the non-Gaussian closure scheme provides improved response estimates that are closer to stochastic averaging results. Moment-closure techniques are then extended to consider a riser under combined parametric and external excitation. For a fixed level of parametric excitation, the response statistics are found to vary nonlinearly with external excitation levels. The Gaussian closure scheme is found to overpredict structural response for the case of pure parametric excitation and to underpredict structural response for the case of pure external excitation.