Damage Diagnosis of Structures Based on Vibration Mode

Based on the structure modal parameter identification method, the free vibration signal is first extracted using random decrement technique, and then the cross-correlations of different respond points obtained through NExT method are taken as the inputs of the modal time domain identification, and parameter identification is obtained by means of complex exponential method .. The local damage diagnosis is achieved according to the modal frequency movement. In order to ensure the accuracy of identification, the method of reference points selection is analyzed. The experiment shows that, the reference points selection method discussed here is valid in improving the accuracy of modal parameter identification, and the modal frequency could be used to judge the occurrence of damage.