i’ll suggest an inclusion of GMSH as advanced mesher, many feature and algorithm are more robust and better than currently used.
sometime Netgen failed to meshing 3D tetrahedral quadratic type in following a curved geometry. 2D Quad-dominant also not always work at curved intersection i.e required further post-process in smoothing.
However, it seems GMSH more advanced and robust. there’s few algorithm called
Blossom, full quad unstructured
Quasi-structured, quad
HXT, quality tetrahedral
R-tree, automatic hex-dominant
etc.
Salome CAD/CAE also been included the features in their latest version. the documentation can be found in their web links.
i guess the workflow is create plain text files with geo extension, include or import using merge of CAD files (IGS,STP,BRP) then preset the meshing algorithm definition. and save the mesh as UNV and opening to displays.
the algorithm or hypothesis preset is not an easy, but let the user experimenting. below my example and results using Quasi-structured quad and R-tree hex-dominant,
Of course, it would be great but integrating Gmsh into PrePoMax in such a way that it’s user-friendly might be really difficult. FreeCAD did it but not for hex meshes and probably with a need for some significant improvement. Interestingly, Gmsh seems to fail more often than Netgen in FreeCAD. Perhaps because of the less automated character of Gmsh.
above my cases were Netgen mesher failed on quadratic setting and following geometry. however GMSH is not, and Hex-Dominant is successful also.
another case in 2D Quad-dominant at model of pipe intersection i can posting if required. it’s failed and thrown an error messages about Jacobian.
GMSH also simple enough to preset for common problems as two of my example in 2D/3D, only with fixed single parameter in element size factor it almost work for any complex models.
regarding to mesh refinement at some area interested, it seem to be possible also, since GMSh can grasp point identity from CAD models included.
hello again, now i know what’s mean to be “user friendly”. it’s a pre-calculated values recommended to similar menus as Netgen currently implemented.
this feature of GMSH in Salome CAD/CAE not available also. it seems due to unpredictable and complexity of the algorithm. however, it can be use by only single parameter of element size factor instead of five as Netgen set, it cam be fixed to values of 0.125 and it’s rare to required to modify at most cases of both 2D and 3D meshing.
another setting in mesh refinement also possible by mapping the point of CAD to GMSH models and define mesh intensity at the point interest. however, i’m not yet really know how to and still try.
i will inform further about my learning curve in using GMSH as advanced mesher.
can it be more specific, what’s type of improvement: element mesh quality or the finite element solver itself? to my understanding it’s only problem when using linear element type.
currently these problem can be eliminate by using quadratic element type or refined the mesh, so fraction of tetrahedral element can be less.
regarding to tetrahedral mesh, even it has advanced still i did not found any features to define number of element trough the thickness. this can be problematic for thin part attached on a body. in contrast, hexa-dominant can be easily achieved as my example below,
hexa-dominant meshing is fairly new technology at implementation (Ansys, Femap, Adina, Cubit, etc) the improvement is in mesh quality due to minimize fraction volume of tetrahedral element inside.
**edited
may i correcting about minimum two element of thin part in tetrahedral meshing, it can be set by maximum element size to half of the thickness. the disadvantages is in computational times were at least doubled.
@synt What Gmsh settings did you use to produce the Hex mesh above ?
The reason I ask is because if I use the settings that you show in the sheet-metal bracket above, I get the below error when trying to import the .inp (Abaqus format mesh) file into PrePoMax.
Regarding to hex-dominant mesh, please follow my comment at this treads discussion
After finished, check Tool-Statistic in GMSH and be sure there’s only contains hexahedral and tetrahedral element. Nothing else i.e pyramid since it’s not supported by CalculiX CCX solver.
openings in CalculiX GraphiX is good decision, since many further process may required
*Display group of element type
*Merging nodes by smallest tolerances
*Merging collapsible element
*Element mesh quality (Jacobian range numbers)
*Remove unwanted element type 1D and 2D if available
were mostly above features, currently not available in PrePoMax, alternatively someone can use Salome CAD/CAE instead of CGX
