PSI - Issue 80

Haomiao Fang et al. / Procedia Structural Integrity 80 (2026) 53–64 H. Fang et al./ Structural Integrity Procedia 00 (2025) 000 – 000

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can be used to distinguish anomalous signals from healthy ones.

Figure 6: The reconstruction outcomes of the test signal for (a) healthy path and (b) damaged path.

The reconstruction outcomes of both healthy and damaged paths are illustrated in Figure 6. For the damaged path in Figure 6 (b), a significant reconstruction error is observed, indicating the presence of damage. In contrast, for the healthy path in Figure 6 (a), the reconstructed baseline closely matches the test signal. Accordingly, the reconstruction discrepancy for transducer path , resulting from the presence of damage, is defined by (8): = 1 − ( , , , ) (8) 3.2.6 Rapid probability-based diagnostic imaging (Rapid PDI) The Rapid PDI technique is employed to estimate the probability of damage presence at specific points on the plate, with the results visualized as a grayscale image. This approach enables a fast and intuitive assessment of structural health without requiring prior knowledge of the exact damage characteristics, making it particularly suitable for real time or large-area inspections [18]. For RAPID algorithm, the imaging field ( , ) is formulated by (9), (10), and (11). ( , ) = ∑ ∙ ( , ) = 1 (9) ( , ) = { ( , ), @ ( , ) < , @ ( , ) ≥ (10) ( , ) = √( − ) 2 +( − ) 2 +√( − ) 2 +( − ) 2 √( − ) 2 +( − ) 2 (11) Where a, r corresponds to the actuator and sensor of the transducer path i . is set as 1.05 to adjust the coverage of the transducer path. 4. Results and discussions 4.1. Experimental setup A 523 mm * 527 mm composite coupon panel is manufactured of a unidirectional prepreg thermoset material IM7/8552 which has a layup is [0/45/ −45/90] 2 and a thickness of 2 mm. Eight DuraAct PZTs made by PI ceramics are surface mounted on the plate using adhesive films and guide wave signals are collected with a LASAR system [28]. The geometry diagram and PZTs distribution are illustrated in Figure 7. A chirp signal with a frequency linearly increasing from 1 = 10 kHz to 2 = 600 kHz is employed to excite a broad frequency spectrum, and a toneburst reconstruction is performed to extract the narrowband response near a central frequency of 50 kHz , as defined by (12) and (13):