PSI - Issue 75

J. Filho et al. / Procedia Structural Integrity 75 (2025) 353–362 J.Filho, L. Wittevrongel, F. Pieron, P. Lava / Structural Integrity Procedia (2025)

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Fig. 3. (a) Williams’s series expansion domain outlined in the imposed data, (b) crack- tip obtained by opening displacement and using Williams’ formulation and (b) measured residuals. The adjusted SIFs using Williams’ formulation are depicted in Fig. 4. The blue and red curves show the reference values of and that were used to deform the images, respectively, while the cross and circular symbols depict the adjusted (blue) and (red) using the imposed FEA full-field displacements and digital twin, respectively. The relative errors are also depicted. As can be seen, a good matching was observed for both SIFs. According to Fig. 5(a), small relative errors were identified for the adjusted parameters using the imposed FEA full-field displacements, as expected. DIC possesses intrinsic errors like shape function mismatch, interpolation bias and pattern-induced bias, explaining why the observed relative errors in the digital twin, depicted in Fig. 5(b), were bigger than the errors present in Fig. 5(a). Moreover, small errors are also introduced in the image deformation, though smaller than typical errors caused by camera noise. This illustrates the importance of fully understanding the uncertainties present in DIC measurements. The digital twin also shows that the carried-out implementations to extract SIFs and the crack-tip position from a full-field- fitting approach using the Williams’ series expansion was able to reconstruct with satisfactory accuracy the imposed parameters.

Fig. 4. Reconstructed SIFs.