LAUSR

Abstract Vibration modal analysis is a significant technique in dynamic analysis that has been widely used for structural damage detection and health monitoring. To accurately identify the modal parameters of a structure, a non-destructive method using camera-based heterodyne interferometry and acoustic excitation is proposed in this paper for modal analysis. Based on a high-speed complementary metal oxide semiconductor (CMOS) camera, full-field images of a vibrating structure with a high-density spatial resolution can be rapidly collected and processed to extract adequate vibration response data for modal analysis using heterodyne interferometry. Combined with an acoustic wave as an excitation source to trigger the vibration response of the structure, impairment can be avoided. To verify the validity of the proposed method, an experiment for extracting the modal parameters of a steel cantilever beam is introduced. During the test, the vibration response of a beam under the excitation of random white noise is detected using heterodyne interferometry to extract the natural frequencies. The mode shapes are retrieved from the full-field vibration response determined via heterodyne interferometry using an acoustic wave at natural frequencies. The results show significant consistency with those from finite element analysis (FEA) and laser Doppler vibrometry (LDV), demonstrating that the proposed method is an effective technique for vibration modal analysis.