PSI - Issue 77

Francisco Afonso et al. / Procedia Structural Integrity 77 (2026) 584–592 F. Afonso et al. / Structural Integrity Procedia 00 (2026) 000–000

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(a) Macro lens setup.

(b) Vibration measurement, as seen from Prophesee’s Metavision SDK 4.

Fig. 7: Macro lens setup and grid measurement using Prophesee’s Metavision SDK 4.

The vertical and horizontal bands in 7 are elements of the grid target, in particular, the 0.1 mm thickness lines which are spaced 2 mm apart, appearing large due to the 4.0 × magnification. The dominant frequency was approximately 32.3 Hz, similar to the 32.5 rps reported in Chapter 2 for the balanced fan. 3.4. Frame camera with macro lens and balanced fan The configuration with a macro lens and balanced fan was also tested with the Basler frame camera, where two distinct target types enabled two measurement methods: image tracking and digital image correlation (DIC). A region of interest was defined to enable faster frame acquisition at 300 fps. In order to get good results, external synchronization hardware was required to ensure precise camera timing and triggering. 3.4.1. Image tracking For image tracking, the grid target was used. ”E ffi cient subpixel image registration by cross-correlation” by Manuel Guizar is a MATLAB software tool which was used to track a grid point over time [17]. Figure 8 shows the region of interest, the measured displacement time series and the vibration power spectrum. The dominant frequency is around 33.0 Hz, closely matching the 32.5 Hz reported in Chapter 2.

(a) Region of interest displaying a par tial grid pattern.

(b) Displacement over time and power spectrum vibrations.

Fig. 8: Grid target as seen from the frame camera and image tracking results.