PSI - Issue 47

Domenico Ammendolea et al. / Procedia Structural Integrity 47 (2023) 488–502 Author name / Structural Integrity Procedia 00 (2019) 000–000

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4.2. Mixed-Mode four-point bending test The considered specimen geometry, including the assumed constraint and loading schemes, is represented in Figure 7. The fixed dimensions of the beam are L = 365 mm, l = 151 mm, H = 76 mm, and W = 38 mm, whereas the distances C and C 1 are variable. In particular, four different geometric configurations are considered by varying the values of such distances, like what was done by Ma and coauthors ((Ma et al., 2021)). The values of C and C 1 for these cases (named as Case 1, Case 2, Case 3, and Case 4) are reported in Table 1.

Figure 7. Mode-II asymmetric four-point bending beam: a schematic of the geometry and boundary conditions.

Table 1. Mixed-Mode asymmetric four-point bending test: geometry parameters.

C 1 [mm]

Case

C [mm]

Case 1 Case 2 Case 3 Case 4

25 25

0

12.5

37.5

25

50

37.5

It is worth noting that Case 1 involves a pure Mode-II crack propagation, whereas the remaining cases lead to Mixed-Mode fracture conditions. The adopted Young’s modulus is 40 GPa, and the Poisson’s ratio is set equal to 0.2. The resulting load-CMSD curves for all the considered cases are reported in Figure 8(a). It can be observed that the peak load increases at increasing values of the Mode-II contribution. Such a toughening effect is mainly due to the induced increment in the crack path tortuosity, which is clearly visible in Fig. Figure 8(b).