PSI - Issue 42

Harry O. Psihoyos et al. / Procedia Structural Integrity 42 (2022) 299–306 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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3.2. Mesh scheme strategies The mesh scheme stra tegies tha t are examined in the current analysis are uniform cartesian, cartesian with projection factor and layered tetrahedralmesh. Cartesianor voxelmeshing is the most commonmesh scheme that has been used for the simulationof SLM process. Cartesianmeshingutilises hexahedral finite elements or voxels for the discretiza tion of the layers to mimic the layer-by-layer fabricationof the SLM part. The voxels canhave constant or varia tional size throughout the model of SLM part. Usually, the element size accounts for the thickness of many merged layers that form a lumped layer or superlayer to make the analysis more efficient (Psihoyos et a l., 2022). Nevertheless, in these cases the small and complex geometric features of the processed part are not discretized in deta il leading to inaccurate simulation. To this end, a projection factor can be used in ANSYS software to better discretise the tiny details with cartesian mesh scheme. This factor varies from zero to one, with zero accounting for no adjustment andone to the maximumadjustment of the elements to the complex features of the part. However, the application of this factormay haveas a result worse element quality due to increased skewness of the elements with uneven aspect ra tio. Hexahedral elements in cartesian meshingcan have linear shape functions with eight nodes per element or quadratic shapefunctions with twenty nodes per element. Layered tetrahedralmesh scheme utilise tetrahedral elements for the discretization of part domain. In opposition to traditional tetrahedralmeshwhere the elementsarbitrary discretise thepart domain, in layered tetrahedralmeshing once the layer thickness is defined, the tetrahedral elements areoriented to forma flat surface. This way, the tetrahedral elements form thick layers equal with layer thickness to model the layer deposition with element birt h and death method. The layer height can be equal with the element size, but it is not necessary, as elements are allowed to be sma ller.Mesh details of the finite element models based on the three meshing strategies are presented in the Fig. 3.

Fig. 3. Mesh details of the finite element models of IN625 single cantilever beam based of the examined meshing strategies: (a) un iform cartesian mesh, (b) cartesian mesh with projection factor and (c) layered tetrahedral mesh. Element size is 0.4mm for all models.