Abstract:

Defect detection techniques, which utilise guided waves, have received significant attention over the past twenty years. Many of these techniques implement the baseline signal subtraction approach for damage diagnosis. In this approach, the baseline signal previously recorded for a defect-free structure is compared with/or subtracted from the actual signal recorded during routine inspections. A significant deviation between these two signals (or residual signal/time-trace) can be treated as an indication of the presence of critical damage. However, the accuracy of this common approach can be compromised by various uncontrolled factors, which include ambient temperature variations, unavoidable inconsistencies in the PZT installation procedure and degradation of mechanical properties with time. This paper presents a new method for reconstruction of the baseline signal, which can compensate for the above influences and improve the accurateness of damage diagnosis. The method utilises 3D laser vibrometry measurements in conjunction with high-fidelity FE simulations. This paper also describes an application of this method to the reconstruction of the baseline signal and detection of damage in beam and plate structures.