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Frequency response (a) and vibration pattern at 11 kHz (b) for LDR in a circular FBH (10 mm radius and thickness 0.8 mm) in PMMA plate (200 × 40 × 4 mm3).
ULT-LDR image of a circular FBH (radius 10 mm and thickness 0.8 mm) in PMMA plate at LDR frequency 11 kHz. Insonation time 15 s; input voltage of the transducer 80 V.
Temperature variation of a FBH at LDR (11 kHz) as a function of input voltage of ultrasonic transducer. Insonation time 15 s.
Comparison between FBH temperature frequency response and LDR acoustic frequency response (shown in Fig. 1 ) squared.
LDR lock-in phase (modulation 0.02 Hz, (a)) and conventional temperature (60 s insonation, ∼3 mW input, (b)) images of a circular FBH in PMMA plate at LDR frequency 11 kHz.
Temperature ACU ULT image of FBH (3 mm radius and 1 mm thickness) in PMMA plate (50 kHz LDR excitation and 54 mW ACU input power (a)); LDR induced temperature rise as a function of ACU power (b).
Imaging of impact-induced damage in multi-ply CFRP plate (photo (a)); laser vibrometry image (b) and ACU-ULT lock-in phase image (modulation 0.03 Hz, (c)) at LDR frequency 69.6 kHz.
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