Baseline-free Active Lamb Wave Based Structure Health Monitoring Method Study

In aeronautical engineering, civil enginering, wind power and other fields, the structure of thestate of health is a major problem which people pay close attention to.Damage of the real-timemonitoring and online evaluation has become a hotspot and difficult problem which engineers andacademics research in recent years. Due to the special mechanism of Lamb wave propagation, theinitiative of Lamb wave structure health monitoring(SHM) become the focus of research in recentyears. In the actual monitoring, measured complex boundary conditions and the influence of factorssuch as monitoring environment, reduce the signal-to-noise ratio of monitoring signal, this makesthe difficulties signal analysis and processing, improve the signal-to-noise ratio of monitoring signalcalled a problem to be solved. In this paper,we make full use of the special advantages of Lambwave propagation and the adaptive ability to focus of time reversal (TR) to monitor and evaluatestructure damage of aluminum plate. The main research content is as follows: first, we introduce theconcept of structural health monitoring, research actuality, application field and the existingproblems and difficulties. Secondly, the paper expounds the spread characteristic of the Lamb,combinating the Lamb wave propagation model,we theoretical analysis Lamb wave method ofstructural health monitoring, on this basis, the time reversal process of Lamb wave is studied. Third,studied the improvement of time reversal method, according to different experiments have beencarried out to verify the geometry of the damage, using the Hilbert transform and window functionto intercept the signal processing methods to extract damage information, studied the damagelocalization algorithm for damage imaging. Finally, in view of the damage monitoring methodbased on reference signal is of poor usability problems, adopt the method of active withoutreference to extract structure internal damage scattering signal, and combined with imaging imagingmethod based on the damage index, the damage to the image can be damage visualization.