Vibration Modal Assessment Using Acoustic Stimulation and Camera-Assisted Heterodyne Interferometry

Modal vibration analysis is crucial in dynamic analysis and has been extensively employed for structural damage detection and health monitoring. This paper proposes a nondestructive approach utilizing camera-based heterodyne interferometry and acoustic excitation for modal analysis, aiming to accurately identify a structure's modal parameters. Using a high-speed complementary metal oxide semiconductor (CMOS) camera, full-field images of a vibrating structure with high-density spatial resolution can be quickly captured and analyzed to obtain sufficient vibration response data for modal analysis through heterodyne interferometry. In the experiment, a beam's vibration response under random white noise excitation is detected with heterodyne interferometry to extract natural frequencies. Mode shapes are derived from the full-field vibration response determined by heterodyne interferometry using an acoustic wave at natural frequencies. The findings display a considerable consistency with results from finite element analysis (FEA) and laser Doppler vibrometry (LDV), indicating that the proposed method serves as an effective technique for vibration modal analysis.