Research On Baseline Free Lamb Wave Damage Detection Method Based On Time Reversal

Lamb wave based active diagnosis method is one of the most effective Structural HealthMonitoring (SHM) techniques due to its sensitivity to small defects in plate-like structures, suchas crack and composite delamination. However, the analysis and interpretation of Lamb waves arecomplicated due to their dispersive and multimodal natures. Meanwhile most active Lamb wavedamage monitoring methods request the health structural response to act as the baseline. Thedifference of the damage structural response and the baseline is made to obtain the damagescattering signals. Such process will be affected easily by noises, such as structures andenvironment varieties, vibration, and so on. Therefore, it is critical for the development of a robustmonitoring system to minimize false-positive indications of damage caused by the undesiredoperational and environmental variation of the structure. The issue of minimizing damagemisclassification has been addressed in this article by developing an instantaneous damagedetection scheme that does not rely on past baseline data. The proposed instantaneous damagediagnosis is based on the concepts of time reversal and extreme value theory. The proposeddamage diagnosis has been tested for detecting damage in composite plates by the experiments.