PSI - Issue 56

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Estera Vălean et al./ Structural Integrity Procedia 00 (2023) 000 – 000

Estera Vălean et al. / Procedia Structural Integrity 56 (2024) 58 – 64

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Fig. 3. Force vs displacement curves for notched specimens under tensile loading: a) PLA; b) PLA-CF.

The results have been summarized in terms of SED value as shown in Fig. 4. In particular, Fig. 4 a) and c) show the procedure considered to determine the control volume characteristic length ; due to the variability that can be seen in the results also for specimens having the same nominal geometry, has been determined by minimizing the error in the SED summary of the results. Due to the behavior shown by both materials, it was not possible to consider them as brittle and an equivalent elastic model had to be established. Therefore, the critical strain energy density, determined through the smooth specimens, was evaluated considering the true strain – true stress curve of the material leading for PLA to and =0.81mm while for PLA-CF to and =0.30mm. According to the explained procedure, the critical loads for the different geometries and the different materials considered are predicted by the method with an average error of ±7%; besides, as it is possible to see from Fig. 4 b) and d), the method predicts a minimum of the critical load to failure for 60°, in agreement with the experimental results.