PSI - Issue 79

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

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Crack propagation in all shear-type specimens is illustrated in figure 9. Figures a), b), and c) shown specimens with shell contour. It is evident that the contour elongated, and the crack propagated accordingly. The 90-degree orientation specimens exhibited different behavior, with the crack appearing near the calibration zone in the transverse direction, between the layers, where the cross-sectional area is smallest. This same behavior was also observed in the 90-degree specimens without shell contour, as shown in figure 9 f). For the other specimens, the crack appeared in the calibration zone, initiating in the longitudinal direction, and leading to the fracture of the specimens. In the 0-degree specimens, as seen in figure 9 a) and d), the crack developed between the layers. In contrast, for specimens with a 45-degree raster orientation, the crack propagated through the filaments in the shear zone.

Fig. 9 Crack propagation on all shear-type specimens: a) 0 o raster orientation with shell contour, b) 45 o raster orientation with contour, c) 90 o raster orientation with contour, d) 0 o raster orientation without shell contour, e) 45 o raster orientation without contour, and f) 90 o raster orientation without contour Figure 10 shows 45-degree shear contoured specimens measured using DIC just before crack initiation. Following the tensile test results and the comparison between the mechanical extensometer and the DIC system, shear specimens were tested, and the strain field was recorded to further analyze the material behavior under shear loading.

Fig. 10 Tangential shear strain field of the 45-degree specimen measured with DIC system

4. Conclusions The presence of shell contour does not significantly influence the tensile strength results for specimens printed at 0° and 90° raster orientations. However, for 45-degree specimens, the shell contour improves the tensile strength, and