PSI - Issue 42

Marouene Zouaoui et al. / Procedia Structural Integrity 42 (2022) 680–686 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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and support. Then, a washer solvent-based for debinding is used to dissolve the plastic matrix. Finally, the part undergoes a sintering cycle of 27 hours to fuse the metallic powder in order to get the final solid structure. 2.2. Setup of Single Edge Notched Bending test SENB The specimens are designed according to the work of T. Keiichiro et al. (1992) on the assessment of the fracture toughness under mode I-II. This study focused on mode I fracture or opening mode. The dimensions of the SENB specimen are shown in Fig. 1. The thickness is fixed at 10 mm and the notch angle is equal to 10°.

Fig. 1. Dimensions of the mode I SENB specimen, Keiichiro et al. (1992)

The 3 points bending tests were carried out using an Instron 4484 machine with 150 kN cell force. A loading speed of 0.5 mm/min was used.

Fig. 2. Bending test machine

2.3. Auxetic and honeycomb patterns design On the surface of SENB sample, three kinds of cell patterns are applied with similar cell densities to ensure the relevance of the comparison. A conventional honeycomb cell pattern (see Fig. 3 (b)) is chosen to emphasize the benefit of introducing auxetic cell patterns. The effect of the auxetic cells ’ orientations will be also checked. An auxetic pattern at 0° parallel to the notch direction (see Fig. 3 (c)) will be compared to a cell pattern at 90° perpendicular to the notch direction (see Fig. 3 (d)).