PSI - Issue 79

416 Osman Bayrak et al. / Procedia Structural Integrity 79 (2026) 413–420 σ 467 � τ 80 � 1 (1) The porosity induction process was applied on both tensile and bending test models. Following the induction of the porosities, tensile and bending boundary conditions were applied in the models. Boundary conditions and phase configurations of the models were given in schematical drawings in Fig. 2. Nodes on the left edge of the tensile test models were fixed in x direction. A node at the middle of the left edge was also fixed in y-direction in order to prevent free-body motion. Nodes on the right edge were tied to a free node that is positioned outside the model. The tying was done for displacement degree of freedom in x-direction, so that the nodes can move independently in other directions while they are moving together in x-direction. For bending test models, in order to reduce the computational costs, the same RVE was used at the middle section of the beam specimen geometry; left and right sections of the specimen was not defined any dispersions of graphene, and therefore no porosities. Rather, they were defined as homogenous media with only elastic properties of nanocomposite. This configuration would not affect the reliability of the model as the highest stresses would occur at mid-section of the beam specimen model, so would the failure. Failure definition of matrix was made with maximum failure criteria of tension and compression. Tension failure was based on the tensile strength of Si3N4, which is ~500 MPa. Compression failure was assumed 10 times of the tension, which is 5000MPa. The models were constrained with rigid circular geometries in y direction. A touching contact with no friction between the circles and the beam specimen model was defined. Two bottom circles were fixed in place while the upper top circle was applied displacement in y-direction. Loading was displacement controlled in all test models. Appearance of a pore in the interface a real microstructure (reproduced with permission from Ceramics International, 45, 4814 (Bódis et al., 2019)) (a); partial contact deactivation is applied in order to induce sparsely distributed pores in the interfaces of the FE models (b).

Figure 2 Schematical representation of boundary conditions for tensile (a) and bending (b) test models. Details on the boundary conditions and the phase configurations are given in (c) . Model dimensions were: ~8µm by ~11µm for tensile model; and ~8µm by ~84µm for bending model.