A non-destructive technique using digital holographic vibrometry and Lamb waves for quality determination of polymer-metal laminates

We used digital holographic vibrometry (DHV) as a non-destructive method to detect debonding areas in laminates made of aluminum and polymer (polylactide, polyvinylidene fluoride or polycarbonate). At low frequencies (up to 30 kHz) [Formula: see text] Lamb waves were excited and the amplitude and the phase patterns of the vibration of the sample were simultaneously registered for metal and polymer side of the laminate. Based on these patterns debonding areas in laminates were localized. The transmission properties at low frequencies were also studied in terms of: the frequency range for which regular Lamb waves have been observed, Lamb wave amplitudes and Lamb wave propagation velocity depending on the frequency. We have shown that these properties also change when a defect occures in the laminate. Even when we could not localize the defect it was still possible to detect if a sample was damaged based on the behaviour of the Lamb waves.