## 5 Summary  
According to the investigated parameters in the literature, 3D parameters have different impacts on the fatigue performance of FFF prints. For PLA, the best tensile fatigue strength is achieved when the raster angle is set to 45\({}^{\circ}\). For PETG prints, 45\({}^{\circ}\) prints exhibit the highest performance under a low-stress tensile cycle. When subjected to high stress amplitudes, 0\({}^{\circ}\) prints showed superior performance. For porous PLA prints, grid patterns (0/90\({}^{\circ}\)) showed higher compressive fatigue performance than other patterns. It was also shown that structures with round pores resist fatigue loads better than pores with a sharp edge due to a lower stress concentration. The highest rotating bending fatigue performance in PLA prints is achieved when a honeycomb infill pattern, a higher layer height, a higher infill density, and a horizontal build orientation are used during printing. According to the existing data, while print velocity showed no significant influence on the fatigue performance of PLA prints, the infill density and layer height possessed the highest impact. In ABS prints, 45/\(-\)45\({}^{\circ}\) grid infill patterns outperformed rectilinear patterns under tensile fatigue loading, and among the various rectilinear patterns, 0\({}^{\circ}\) prints outperformed prints with other raster angles. The 0\({}^{\circ}\) raster angle also produced the best flexural fatigue performance for ABS and PC prints. It was also shown that for ABS and Ultem 9085 FFF parts, Y prints had the best tensile fatigue performance. Like PLA prints, honeycomb infill patterns and a horizontal build orientation produced ABS samples with the highest rotating bending fatigue performance. The flexural fatigue performance of ABS prints showed a direct association with the nozzle diameter and layer height, with the nozzle diameter having a more noticeable impact. Table 3 summarizes the results reviewed in this study. The studied 3D parameters are listed in the left column, and the loading types are denoted in the first row. Each cell shows the relationship between the studied 3D printing parameter and the mechanical performance of a typical FFF print under a specified fatigue type. Upward arrows in the  
cells show a direct relationship between the studied parameter and fatigue performance, meaning that by increasing the parameter value, the fatigue performance for the selected loading type increases. Conversely, downward arrows demonstrate an inverse relationship. The dash sign indicates that not a certain relationship can be extracted; meaning that in some studies, a direct relationship has been reported, while in other studies, an inverse relationship has been found. In addition, blank cells represent the proportions that have not been investigated yet. As can be seen in Table 3, the effect of other parameters, such as extrusion width, perimeters, number of shells, and solid layers, on the fatigue response of FFF prints has not been studied so far. Moreover, the number of relevant studies on other parameters is still insufficient, implying that further investigation should be conducted to fully understand the interaction between 3D printing parameters and the fatigue performance of FFF prints. It should be noted that Table 2 only represents the data studied in this review and, thus, is limited to a specific range of materials and 3D printing parameters (e.g., raster angles of 0\({}^{\circ}\), 45\({}^{\circ}\), and 90\({}^{\circ}\)). According to the published data, only the correlations and trends, not the optimum values, can be identified, as this requires an optimization study.