PSI - Issue 79

Popa Cosmin Florin et al. / Procedia Structural Integrity 79 (2026) 354–360

358

For the shear specimens, the Force-Displacement plots are also shown in Figure 6. Figure 6 (a) presents the curves for contoured specimens, trimmed near the yield point for clarity. The values across specimens are quite similar, with the 45° specimen showing a higher force value compared to the other raster orientations. Specimens printed at 0° and 90° exhibit comparable curve shapes and yield points. Figure 6 (b) displays the Force-Displacement curves for un contoured shear specimens. The curves were cut off after the yield point for better observation of the initial slope. Specimens printed at 90° show a lower force value compared to the contoured specimens, but their deformation values remain close. The shell contour does not significantly influence the results for the 0° and 45° specimens. However, the 90° specimens are impacted by the contour, which increases their stiffness and ductility. Shear strength values are very scattered, especially for un-contoured specimens. Specimens built on a 0-degree raster angle have a big error bar due to the scattering of the results.

Fig. 7 Shear strength for the: a) contoured specimens, and b) un-contoured specimens

To provide clearer insights, the results from the extensometer were compared with those from the DIC system measurements on a 0-degree raster orientation tensile specimen. The blue line represents the curve measured by the extensometer, showing a smooth progression that clearly outlines both the elastic and plastic regions. The red curve corresponds to the DIC measurement, which follows a similar trajectory but with a slight deviation at the beginning. This discrepancy is due to the DIC system capturing a higher strain at the start, as it includes the effects of pre-loading on the specimen. In contrast, the extensometer was attached after the specimen had been pre-loaded. Ultimately, both curves converge at the same point, where the specimen failed, at 7.6% strain. Both methods demonstrate high accuracy. The advantage of using the DIC system, especially with shear specimens or thin plates, is that it allows for strain measurement across the entire surface while attaching an extensometer would be difficult or impracticable.

Fig. 8 Comparison between results with extensometer and DIC system