PSI - Issue 77

H. Lopes et al. / Procedia Structural Integrity 77 (2026) 673–680 H. Lopes/ Structural Integrity Procedia 00 (2026) 000 – 000

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Fig. 4. Incremental summation of band-pass filtered phase maps at specific time instants: (a) 8 s; (b) 32 s; (c) 48 s; and (d) 96 s.

Figure 5 compares the summation images derived from three different shearing configurations: pure x -direction shearing (5 mm), pure y -direction shearing (5 mm), and diagonal 45° shearing. As previously stated, the 45° configuration is achieved by applying a 5 mm shear component in both the x and y directions. As the images demonstrate, the contours of the damaged regions are revealed according to the shearing direction. Specifically for the higher impact damage, the vertical contour is visible with x-direction shearing, and the horizontal contour is visible with y-direction shearing. Conversely, the 45° diagonal shearing clearly reveals both horizontal and vertical contours, confirming that the combination of shearing directions provides the most comprehensive definition of the damage contour region.

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Fig. 5. Effect of shearing direction on damage signature detection: (a) x-direction; (b) y-direction; and (c) 45-degree direction.

4. Conclusions This study successfully demonstrated a novel, baseline-free methodology for enhancing the identification of internal damages in a CFRP composite plate using digital shearography (DS) phase map analysis. The technique applies band-pass filtering followed by the coherent summation of multiple phase maps, which significantly improves the SNR by isolating persistent damage-related perturbations and suppressing random background noise. This process is crucial because it not only enables superior identification of both the location and size of the low-energy impact damage, but it also confirms a direct correlation between damage size and impact energy. Furthermore, generating

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