环境激励下船体模态参数识别实验研究

Modal parameter identification of a ship structure under ambient excitation

运行模态识别是一种仅仅根据环境激励下结构振动响应提取结构模态参数的方法,常基于环境激励为白噪声特征的情况。由于船舶螺旋桨、主机及其它激励的特点,船体结构响应在频率上既有较强的单频成分,低频段也存在非常丰富的相对较弱的成分。因此航行中的船舶所受激励呈现为白噪声和确定若干单频频率的叠加作用。基于船舶结构的环境激励特点,讨论船舶结构运行模态参数识别方法,及NExT/ERA方法在船体结构总体模态识别中的应用,通过一艘实船模态实验识别了船体模型的总体模态参数。

Operational modal identification method is a procedure that ertracts modal parameters of a structure only from its response, it is always based on an assumption that excitations are White noisel For a ship structure, its excitations are very complex, including sea waves, main engine and propeller excitation and so on. These excitations can be assumed to be a combination of white noise and some harmonic signals. Here, based on characteristics of ambient excitations Of a ship structure, special methods for operational modal parameter identification were discussed, and then application of NExT/ERA in a ship structure was introduced. At last, these methods were verified with the general modal parameter identification of a real ship structure.