船舶结构高阶动力分析的模型简化方法研究

Model simplification on ship structural high frequency dynamics

针对船舶结构动力分析的模型简化条件及方法进行研究,通过讨论阻尼对结构动力响应分布的影响,从波动角度研究了以局部结构代替整体模型进行动力分析的模型简化条件,提出了船舶结构高阶动力分析模型简化的行波法。研究表明,阻尼可降低结构的动力响应,并使结构动力响应随距激扰力作用点的距离呈指数函数衰减;结构动力模型能否简化很大程度上取决于阻尼、激扰频率及结构物理参数等条件,激扰力在简化模型与原结构中产生的弯曲波传播距离相差整数倍波长时,简化模型的动力响应可最大限度地与原结构保证一致,进而提出了均质结构及板架等复杂结构动力分析的模型简化定量方法—行波法;并采用算例验证了其有效性。

The model simplification conditions and method for ship structural high frequency dynamics are examined. Based on wave traveling theory, structural dynamic model simplification conditions of using local structure replacing the whole model are studied by discussing the influence of damping to structural dynamic response. And traveling wave method, a model simplification method for ship structural high frequency dynamics is thus derived. Study shows that damping can diminish structural vibration amplitudes. And vibration decays in an exponential way along the beam with distance from excitation point. Whether structural dynamics model can be simplified or not is highly dependent on damping, exciting force frequency and structural physics parameters. When flexural wave prorogation distance between simplified model and original structure is N （PC is an integral） times of flexural wave length, dynamic response of simplified model is most likely in accordance with original structure. Traveling wave method and quantitative model simplification con- ditions for uniform ＆ complex structure （such as ribbed plates, etc） are thus presented. And validations have verified its correctness.