PSI - Issue 56

Mihai Marghitas et al. / Procedia Structural Integrity 56 (2024) 26–32 Author name / Structural Integrity Procedia 00 (2019) 000–000

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3. Results and discussions Relations (1) and (2) were used to estimate the stress intensity factors and . The obtained experimental results are shown in Table 1. The average value of symmetric loading was considered the mode I fracture toughness of the additive manufactured resin, =1.012 ± 0.057 MPa m 0.5 . Table 1. Experimental results Specimen [mm] [mm] [mm] 1 [mm] 2 [mm] [N] [MPa m 0.5 ] [MPa m 0.5 ] 2.6-1 40.02 6.30 17.7 30 2.66 1160 0.000 0.904 2.6-2 40.10 6.24 17.3 30 2.66 1070 0.000 0.831 2.6-3 40.00 4.33 17.3 30 2.66 875 0.000 0.981 2.6-4 39.92 3.91 17.5 30 2.66 739 0.000 0.924 4.0-1 40.17 4.40 16.3 30 4 957 0.312 0.923 4.0-2 40.03 5.30 17 30 4 1000 0.280 0.820 4.0-3 40.00 5.89 16.5 30 4 1100 0.273 0.800 4.0-4 40.10 4.35 17.6 30 4 803 0.277 0.815 6.0-1 39.98 6.28 17.4 30 6 927 0.519 0.557 6.0-2 40.02 6.30 16.3 30 6 903 0.486 0.523 6.0-3 39.97 6.24 17.4 30 6 947 0.534 0.573 6.0-4 40.10 6.35 17.7 30 6 817 0.453 0.489 8.0-1 40.16 3.57 17.8 30 8 520 0.780 0.474 8.0-2 40.09 5.22 17 30 8 839 0.844 0.511 8.0-3 40.04 3.23 17.1 30 8 419 0.686 0.414 8.0-4 40.06 3.76 17.5 30 8 469 0.666 0.403 12.0-1 40.00 4.42 17.7 30 12 535 1.040 0.283 12.0-2 40.06 2.96 17.5 30 12 335 0.965 0.263 12.0-3 43.74 3.77 17.5 30 12 425 0.803 0.261 12.0-4 40.10 6.33 17.7 30 12 715 0.966 0.264 30-1 40.17 3.37 18 30 30 200 1.054 0.000 30-2 40.00 4.32 18 30 30 224 0.927 0.000 30-3 40.00 4.32 16.8 30 30 257 1.028 0.000 30-4 40.12 3.40 17.3 30 30 203 1.041 0.000 Generally, fracture criteria for mixed mode loadings provide: • a combination of the stress intensity factors ( and ) and fracture toughness ( ), i.e.: ( ) 0 , , = II IC I F K K K • the crack initiation angle . For comparison in the case of plane mixed mode fracture, four classical fracture criteria are considered, namely the Maximum circumferential Tensile Stress (MTS), the Minimum Strain Energy Density (SED), the Maximum energy release rate ( ), and the Equivalent Stress Intensity Factor (ESIF); their mathematical formulation is provided in Table 2. (3)