应变传递率运行模态分析方法及应用

A strain transmissibility approach for operational modal analysis and its application

运行模态分析方法在推导过程中多假设激励为白噪声,造成在应用上有一定的局限性。为解决此问题,提出一种利用应变测量的传递率运行模态分析方法。首先推导应变传递率表达式,利用两种不同载荷情况下的应变传递率函数构造伪频响函数矩阵,采用频域子空间估计方法来识别系统极点,然后使用奇异值分解技术对传递率矩阵分解获得模态振型。采用有限元仿真算例和飞行颤振试验数据对所提方法进行验证,结果表明,在非白噪声激励条件下,该方法仅利用测量的应变响应就可准确识别结构模态参数。

Most operational modal analysis algorithms are based on the assumption of white noise excitation,which has some application limitations.To solve this problem,a method of operational modal analysis using the transmissibility of strain measurement is proposed.The expression of strain transmissibility function is derived,the pseudo frequency response function matrix is constructed using the strain transmissibility under two different load conditions,the frequency domain subspace method is used to identify the system poles,and then the singular value decomposition technique is used to decompose the transmissibility matrix to obtain the modal shape.The proposed method is validated using finite element simulation examples and flight flutter test data.The results show that under non-white noise excitation conditions,this method can accurately identify structural modal parameters using only measured strain responses.