## 3 Results
### Numerical Simulations  
The FEM is the technique of subdividing all systems into their constituent components or elements. In the majority of research, FE-simulation findings are compared to experimental values; nevertheless, the FEA technique varies greatly across studies, and a systematic approach to constructing the model is often not documented. Additionally, it must be emphasized that strut-based porous structures are often categorized according to their deformation mechanics. The structure is considered to be dominated by bends. If the struts bend or buckle under compressive force; alternatively, for certain porous architectures. Some struts may support an axial tensile load during compression, and these constructions are categorized as stretch dominant [81]. It is unknown how deformation mechanics and other kinds of cellular geometries would impact convergence, precision, and the reliability of findings as compared to physical-mechanical testing at a minimal computing cost [82]. This will first be performed on structures dominated by bending, with the expectation that it can be extended to structures dominated by stretching, stochastic structures, and graded structures. An FE-model was constructed by ANSYS to determine the stress and strain values around the concentrator. Figure 20 shows the highest primary stress distribution at the surface of the specimen around the drilled hole for the B2 test at the maximum load point. Figure 19: Fractured section of a fatigue test specimen (as-build CUB S). (**a**) the struts failed by fatigue (partly failed by fatigue) are golden because of the heat tinting. (**b**) fractured specimen after a fatigue test. The fracture is away from the bulk/ cellular structure. Reprinted with permission from ref. [79], 2016, Elsevier. The research scientific method is a sequence of processes that follows a pattern. Generating high-quality CAD models. Generate lightweight designs that can be produced by additive manufacturing technology. The printed AM components may be a cylindrical, dog-bone specimen, a Compact test (CT) specimen with a solid material, or porous structures for the multiaxial testing. The AM manufactured specimen were admitted for post-processing such as machining, polishing, shot peening, laser peening, sandblasting, and HIP process to improve the fatigue life of the materials. Then, the post-treatment process leads to different multiaxial testing. The machine operates in force control, whereby the force was calculated by considering the load-bearing cross-section that excludes the area of the channels. Consequently, the applied force was lower for samples with higher numbers and larger diameters of channels, respectively, to consider an equal nominal maximum stress amplitude for all samples tested. For building the models and solving the governing equations, the ANSYS implicit solver was utilized. For modeling the struts in the microscale part of the model, Timoshenko beam elements with three integration points (BEAM189 in ANSYS) were employed, while eight-noded brick elements (SOLID185 element type) were employed for discretizing the macroscale portion of the method. The fatigue failure pattern anticipated by numerical modeling for all structures is shown in Figure 21. The figure describes the displacement contour in the direction of loading. The geometry of the failure pattern may reveal information about the formation of cracks and the distribution of macro stress in scaffolds. The development of shear bands indicates that shear forces may not be the primary failure mechanism at the macro scale. In contrast, cyclic tensile stress owing to bending moment played a crucial part in the fatigue failure mechanism of the microscale strut. The experimental findings demonstrated that the fatigue failure surface was 45\({}^{\circ}\) angled concerning the loading direction. Again, there was a strong correlation between numerical modeling and experimental findings.