以光纤光栅传感器为测量手段实现了基于快速应变响应的结构模态分析。根据位移模态分析的基本原理, 推导了应变模态参数识别算法, 能够仅根据应变响应数据计算结构的模态参数。搭建了一套采样率为5000Hz的光纤光栅快速应变采集系统, 进行了等截面悬臂梁的光纤光栅应变模态试验并识别了悬臂梁的前5阶模态参数。光纤光栅方法与有限元分析结果相比, 固有频率相对误差小于0.6%, 比基于电传感器的位移模态测试结果更接近理论值。基于光纤光栅的应变模态分析方法附加质量小, 能够适应更复杂的测量环境, 具有一定的应用价值。

Structural modal analysis based on fast strain response was realized by using fiber Bragg grating sensor. According to the basic principle of displacement modal analysis, the strain modal parameter identification algorithm was derived, which can calculate the modal parameters of the structure only based on the strain response data. A fiber Bragg grating fast strain acquisition system with a sampling rate of 5000Hz was built. The strain modal test of the fiber grating with equal section cantilever beam was carried out and the first 5 modal parameters of the cantilever beam were identified. Compared with the results of finite element analysis, the fiber grating method has a relative error of less than 0.6%, which is closer to the theoretical calculation than the displacement mode test result based on the electrical acceleration sensor. The strain modal analysis method based on fiber grating has small additional quality and can adapt to more complex measurement environment.