Review of Using Operational Modal Analysis for Condition Monitoring

Modal analysis is critical to better understand structural dynamic vibration characteristics by extracting system’s natural frequencies, damping ratios and mode shapes. Modal analysis has been widely used to structure optimization in the design stage, damage detection and structural health monitoring or condition monitoring. According to whether need artificial exaction, the modal analysis techniques can be categorized as experimental modal analysis and operational modal analysis. Conventional experimental modal analysis has to measure the excitation and corresponding response in the meantime, while operational modal analysis measure system’s response only during normal operating condition. Therefore, operational modal analysis also called output-only modal analysis methods, which have developed dramatically in recent decades because it is promising as means to achieve structural online monitoring, which is highly desirable for critical mechanical system, important buildings and bridges, etc. This paper made a brief review of the development of popular operational modal analysis techniques and their applications in condition monitoring.