结构应变模态辨识的特征系统实现方法

应变模态可以分析动载下结构的应力状态。文中将基于位移响应数据的特征系统实现算法应用于应力应变分析中，建立基于应变测量数据的结构动力学参数辨识方法。首先建立应变的状态空间描述方程。由于应变模态和位移模态是同一物理状态的两种不同表现方式，二者的数学表达式具有相似性，前者是后者的相似变换。在此基础上，给出应变格式的ERA识别方法。利用应变格式进行eigensystem realization algorithm(ERA)分析；不仅可以辨识出结构的频率、阻尼比等动力学参数，而且还可以辨识得到相应的结构应变模态，从而建立应力应变预测响应模型。数值仿真和实验验证表明，该方法对结构应变模态有快速准确的辨识能力。

STRUCTURAL STRAIN MODES IDENTIFICATION METHOD BY EIGENSYSTEM REALIZATION ALGORITHM

Structural strain modes are useful to analyze the stress state under the variational load, which is important to the design of the dynamic strength and the estimation of the fatigue life for structures. In this paper, the state space equations of the strains are obtained firstly. Because the strain modes and the displacement modes are the different expressions for the same physical status, they have the similarity in mathematic definition and the former is the similar transformation of the later. So based on the basic mathematic theory above, the conventional eigensystem realization algorithm (ERA) is generalized to investigate the stress and strain and the dynamic parameters identification method based on the strain data measured is established. Using this method, not only the dynamic parameters, such as frequencies, damping, are identified, but also the strain modes are gained. Then the predictive response model of stress and strain is obtained by the strain modes identified. The numerical simulation and the experiment show that the strain modes can be identified by the proposed method rapidly and accurately.