PSI - Issue 68

Ibrahim T. Teke et al. / Procedia Structural Integrity 68 (2025) 365–371 I. T. Teke & A. H. Ertas / Structural Integrity Procedia 00 (2025) 000–000

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Fig. 3. Stroke upper value in mm and fatigue life cycle graphs.

The practical behavior of these models is further evidenced in Figure 4, which presents graphs illustrating the storage elastic modulus and loss elastic modulus. These graphs indicate that the S-D-S-ER model exhibits more pronounced viscous behavior, while the D-S-ER model demonstrates comparatively rigid characteristics. The enhanced performance of the S-D-S-ER method in three-point bending tests highlights its potential for significantly improving structural durability and efficiency. This underscores the critical importance of advanced numerical techniques in understanding and enhancing the structural performance and fatigue life of materials.

Fig. 4. Loss elastic modulus and storage elastic modulus graph.

In the S-D-S-ER model, crack initiation and propagation are anticipated outcomes influenced by both the loading method and the geometric configuration of the structure, as depicted in Figure 5. Conversely, in the D-S-ER model, crack formation has been observed to occur at a sharp curvature, as shown in Figure 6, which is hypothesized to induce a notch effect within the geometric structure. Another notable finding is that in the D-S-ER model, crack formations emerge near the end of the fatigue life, whereas in the S-D-S-ER model, these formations initiate around the midpoint of the fatigue life—an unexpected outcome. This behavior is attributed to the optimization of the initial geometry through the sub-modeling technique (Teke et al. 2024b), which resulted in a distinct geometric configuration. Consequently, the geometric structure produced by the S-D-S-ER method exhibited behavior akin to that of composite material, in contrast to the more conventional behavior observed in the D-S-ER model.