时频分布与FRFT在环境激励下模态参数辨识中的应用  

Application of Time-Frequency Distribution and FRFT in Modal Parameter Identification under Ambient Excitation

作　　者：樊江玲[1] 张志谊[2] 

机构地区：[1]上海工程技术大学机械工程学院,上海201620 [2]上海交通大学机械系统与振动国家重点实验室,上海200240

出　　处：《上海工程技术大学学报》2011年第3期199-202,206,共5页Journal of Shanghai University of Engineering Science

基　　金：上海市教委085知识创新工程资助项目(JZ0906)

摘　　要：将时频分析方法和分数阶傅里叶变换(FRFT)方法相结合,在环境激励下进行模态参数辨识,可弥补单纯时域或频域方法的不足.将时频分布中的Gabor展开用于识别系统固有频率和阻尼比,各通道响应信号的自相关函数在一定程度上可以减小噪声干扰,增强信号的能量分布,有助于参数的识别.利用FRFT,根据信号在时频面内的旋转角度和脉冲峰值出现的位置可估计激励信号.通过对一个三自由度振动系统仿真结果说明,将FRFT与时频分布的Gabor展开相结合,可以很好地从响应信号中辨识出模态参数和激励信号,为辨识环境激励下的系统模态参数提供了很好的途径.With the combination of fractional Fourier transform（FRFT）and Gabor expansion, modal parameters identification under ambient excitation can make up for deficiencies of simple time domain and frequencies domain analysis methods. The Gabor expansion in the time-frequency distribution can identify natural frequencies and damp ratios. Autocorrelation functions of response signals in each channel can reduce noise and enhance energy distribution to a certain extent, which is helpful for parameters identification. By using FRFT, excitation signals can be estimated according to rotation angles and orientations of the impulse peak in the time-frequency plane. A simulated result of three-degree of freedom vibration system shows that the combination method proposed can provide a reasonable identification of modal parameters and excitation signals from response signals.

关 键 词：模态参数辨识 环境激励 时频分布 分数阶傅里叶变换 GABOR展开 

分 类 号：TU311[建筑科学—结构工程] TN911[电子电信—通信与信息系统]