CMIF方法中模态参数不确定性的计算

Uncertainty calculation in complex modal indictor function identification method

在模态参数识别中,测量噪声的干扰导致识别结果中存在不确定性,这种不确定性可以通过模态参数的统计特性进行描述。以复模态指示函数识别方法为研究对象,利用矩阵的一阶灵敏度分析以及Kronecker代数理论,推导了该识别算法中模态参数方差的计算方法。重点推导了增强频响函数协方差、极点协方差的计算公式。最后通过一个5自由度仿真算例与一个T型结构实测算例对所推导公式进行了验证。

Uncertainty is introduced in modal parameter due to measurement noise. Uncertainties of modal parameter identifica- tion can be described by its statistical characteristics. Variance calculation is illustrated here for the complex modal indictor function identification method based on matrix sensitivity analysis and Kronecker algebra. The emphasis is put on calculating the covariance of enhanced frequency response functions and poles. Finally, both simulated case of a five degrees of freedom system and measurement case of a T-shaped structure are used to demonstrate the accuracy and practicability of the derived ex- pressions.