Assessment of crack bridging in coating sustems: a comparative study between digital image correlation (DIC) and dial gauges in cracl bridging

Resumo:

This study evaluated the crack-bridging capacity of textured coating systems across 60 test 2 specimens using an adapted UEAtc test method, comparing analog dial gauges with two- 3 dimensional Digital Image Correlation (2D-DIC) on acrylic and mortar substrates. Acrylic 4 substrates achieved higher mean bridged crack widths (0.97 to 1.20 mm via dial gauges 5 and 0.39 to 0.51 mm via DIC) than mortar prisms (0.30 to 0.42 mm via dial gauges and 0.21 6 to 0.36 mm via DIC). The elastomeric topcoat increased nominal crack-bridging by up to 7 46.2% in DIC measurements, although substrate type was the mechanically dominant factor 8 in the ANOVA (p < 0.001). Bland–Altman analysis indicated a systematic mean bias of 9 −0.38 mm and significant proportional bias (y = −1.18x + 0.28; R2 = 0.61), demonstrating 10 close agreement for narrow cracks (< 0.40 mm) and progressive divergence at larger 11 openings due to mechanical contact seating effects (ICC(2, 1) = 0.21). The main limitations 12 stem from the spatial disparity between discrete substrate fixtures and continuous surface 13 tracking. In conclusion, DIC is a reliable, non-contact technique for mapping continuous 14 strain fields and identifying initial microcracking, but it cannot directly replace mechanical 15 contact gauges across large deformation ranges without bias compensation.

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https://www.mdpi.com/2075-5309/16/17/3561