关于最小二乘复指数法的频域——时域模态参数识别技术

本文提出了一种识别模态参数的频一时域方法。用适当的谱窗去截取全景频谱,得到仅含一个或少许几个模态的频响函数,并作IFFT,即将所截取的频响函数转换成自由振动响应,然后利用LSCE法识别相应的模态参数.重复上述过程,那么所有包含在测量的频响函数中的模态参数就可以识别出。实验结果表明,文中所提出的方法与原来的LSCE法相比,具有许多明显的优点。它能容易地识别出小能量模态并节省大量的计算时间,而且从LSCE法计算的结果中很容易区别出噪声模态。

A FREQUENCY-TIME DOMAIN MODAL PARAMETER IDENTIFICATION TECHNIQUE BASED ON LSCE METHOD

A frequency-time domain method is suggested in this paper to identify the modal parameters. The frequency response functions (FRF) containing only one or a few modes are obtained by cutting off the panoram frequency response spectrum with a suitable spectral window and transformed to free vibrations by means of IFFT.The corresponding complex modal parameters are identified by using LSCE method. Repeating this procesure, all the complex modal parameters contained in the measured frequency response functions can be identified. It has been proved by experiment results that the method presented here has remarkable advantages compared with original LSCE method. It can easily identify modal parameters of those with relatively weak energy and save much time for calculating, and it become quite easy to tell the noise modes from system modes in the LSCE calculation results, and so on.