如何理解下面这段话？

happy3385

According to Morison's equation the drag force is non-linear. This non-linear formulation is used in the design wave concept. However, for the determination of a transfer function needed for frequency domain calculations, the drag force has to be linearized in a suitable way [9]. Thus, frequency domain solutions are appropriate for fatigue life calculations, for which the forces due to the operational level waves are dominated by the linear inertia term. The nonlinear formulation and hence time domain solutions are required for dynamic analyses of deepwater structures under extreme, storm waves, for which the drag portion of the force is the dominant part [10].

freshmen

意思是“采用频域分析方法计算疲劳，采用时域分析方法进行在极限环境条件下的动力分析。”
原因是疲劳分析中的载荷主要是线性的惯性项，而极限状态下动力分析的载荷主要是非线性的拖曳项

zql2001

非常感谢，学习了