运行模态分析技术在船舶结构振动中的应用

运行模态分析是一种仅基于环境激励下结构的响应来提取模态参数的方法．通常假设环境激励为白噪声进行分析。实际上，船舶航行过程中所受激励十分复杂，除受海浪等随机激励外，还受到来自螺旋桨、主机等确定的单频激励。因此航行中的船舶所受激励应假设为白噪声和确定频率的激励同时存在。讨论运行模态分析方法在船舶结构中应用的可行性；在白噪声激励假设下，提出使用自互谱密度法来进行结构模态参数识别，并用简支梁实验对上述方法进行验证。最后将该方法运用于对某船航行中桅杆的振动响应数据进行分析和讨论。

Application of Operational Modal Analysis in Vibration of Ship Structures

Operational modal analysis is a procedure which allows extracting modal parameters from a structure in operational condition only based on response data under ambient excitations. The input to the structure is assumed to he a stationary white noise. In practice however, the excitations on a ship during voyage can not be assimilated to white noise input, harmonic forces produced by the main engine and propeller are also presented, so the excitations of an operational ship can be assumed to be white noise including harmonic excitations. The application feasibility of operational modal analysis on a ship structure was discussed. And the auto-cross spectrum density method was proposed and verified by a simply supported beam experiment. Then the vibration data of the mast during trial was analyzed and discussed.