基于子空间算法的对称结构重频模态识别

针对飞机等对称结构的重频模态较难识别的问题,在随机子空间算法的基础之上,利用空间投影的性质和响应点位置间的几何关系,分离对称耦合模态,建立对称模态响应和反对称模态响应Hankel矩阵,实现单独利用响应数据识别重频的对称和反对称模态。最后通过仿真算例表明,改进后的方法成功提取了重频模态的振型,避免了传统算法识别结果的中的振型耦合,同时提高了对称模态中固有频率和阻尼的识别精度。

Modal Identification of Symmetrical Structure with Repeated Frequencies Based on Subspace Method

The modals of the symmetrical structure with repeated frequencies,such as aircraft etc,are difficult to identified.For this problem,based on the stochastic subspace method,the paper isolates symmetric coupled modes,through the using of space projection and the geometric relationship of test points,and establishes Hankel matrix with symmetric modal response and the antisymmetric modal response,thus achieving symmetric and antisymmetric modal identification with repeated frequencies using output data only.Finally,simulation examples show that the improved method successfully extracts mode shapes with repeated frequencies,avoids the modal shapes coupling generated by traditional methods,and increases identification accuracy of natural frequency and damping at the same time.