Simulation using the Fine Element Method (EF) requires the use of a simulation mesh. Today, these meshes are generated by simulation software automatically; integrated automatic algorithms “split” three-dimensional (3D) designs into smaller elements that will essentially represent geometric shapes. In addition to division, mesh algorithms usually allow to define into which types of elements the designs should be divided; the most common options are tetrahedral and hexahedral elements.
4-node tetrahedral element and an 8-node hexahedral element
Both types of elements have certain advantages and disadvantages related mainly to the generation of meshes, the accuracy of the simulation and numerical stability. Tetrahedral elements, for example, are well suited to represent very complex structures, but provide less accurate results with the same mesh resolution. Although hexahedral elements can provide more accurate simulation results, they are usually less suitable for geometrically discretizing very complex figures. In addition, sometimes it is not possible to use them allowing a perfect representation of the geometric limits of a design.
For additive manufacturing, a common way to apply hexahedral elements is using the voxel mesh technique. This technique superimposes a voxelized mesh to approximate the underlying geometry, however, with this technique, an erroneous representation of the geometry is likely to occur. To correctly use voxel meshes in the simulation, it is necessary to correct the elementary stiffness by reducing and increasing it from regions that are underrepresented and overrepresented with hexahedral elements, respectively.
Simulation model of a motor support meshed with tetrahedral elements. The original geometry can be approximated very well by the tetrahedral mesh.
Simulation model of a motor support meshed with tetrahedral elements. The original geometry can be approximated very well by the tetrahedral mesh.
Hexahedral elements with corrected stiffness for elements that represent the geometry in the wrong way (red) and those that are within the geometry with complete rigidity.
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