PREDICTION METHOD FOR NON-GAUSSIAN BEHAVIOR AND ITS EXTREMUM OF A MOORED FLOATING BODY IN NON-GAUSSIAN MULTI-DIRECTIONAL IRREGULAR OCEAN WAVES

由于结构运动响应的非高斯性，在恶劣海况下的运动响应或波浪载荷极值预测方法尚未得到发展。还有许多海上设施或散货船遭受结构破坏，沉没和失去了许多人的生命。已有的几个例子表明，瑞利方法对非高斯情况不适用。本文首次尝试对多向波浪中悬链系泊浮式结构物的低频运动极值进行预测。如果只有外部波浪激励是非线性的，而其他项、辐射水动力项、阻尼项和恢复项都是线性的，那么Naess或Kato-Kinoshita提出的方法可以很好地工作，但是，如果我们在运动方程的左手侧引入非线性项，则基于Naess或Kato-Kinoshta的分析方法就不起作用。然后，本文提出了一种适用于全非线性、非高斯过程的时域仿真方法，并在此基础上开发了船舶运动、波浪载荷和船体非定常压力的时域仿真程序。此外，我们引入非线性项，这个时域模拟。

The prediction method of extremum for motion responses or waves loads in severe sea conditions have not been developed yet, since the responses are non-Gaussian. And there have been many marine facilities or bulk-carriers which suffered structural damages, sank and lost many lives. There have reported several examples which shows that the Rayleigh method was not hold for non-Gaussian cases. That is the reason why wer start to develop the practical prediction method of extremum for non-Gaussian process.We first tried to predict extremum of low frequency motions of a catenary moored floating structures in multi-directional waves. If only external wave excitations are non-linear and the other terms, radiation hydrodynamic forces and damping term and restoring term are all linear, then the method developed by Naess or Kato-Kinoshita works well, however, if we introduce non-linear terms in the left hand side of the equation of motion, the analytical method based on Naess or Kato-Kinoshta does not function. Then we conclude that the only practical prediction method for full non-linear, non-Gaussian process is the time domain simulation method which is applicable to so called simulation based design.We then developed the time domain simulation code for ship motions, waves loads and unsteady pressures on a ship hull with advanced speed and in multi-directional waves. Moreover we introduce non-linear terms to this time domain simulation.