2 Mesh Control OverviewThe automated meshing process in SimLab can generate mesh that is suitable for the following Analysis Types.Analysis typeDurability / Stress analysisNVH analysisAcoustic analysisDrop testFluid analysisFor each of the above analysis types, the desired mesh density and the quality of the mesh differs. In SimLab, the output mesh is controlled by specifying Mesh Controls.Mesh controls are applied directly to the CAD models.
3 Mesh Control - Classifications Mesh controls are classified under the following types,Global mesh controlsIt is assigned to bodies or assemblies and all underlying geometry entities, (faces and edges), will inherit this global mesh control.It is mandatory to specify the global mesh control.Local mesh controlsLocal mesh controls are used to control the mesh in a particular region.It over rides the global mesh controls.It is assigned to bodies, faces and edges.
4 Global Mesh ControlsGlobal mesh controls are defined while surface meshing or volume meshing.Surface meshingSurface meshing is used to generate a surface mesh body from a CAD body.Surface elements supported are Tri3, Tri, Quad4, Bar2 and Bar3.Volume meshingVolume meshing is used to generate a volume mesh body from a CAD body or a surface mesh body.Volume elements supported are Tet4, Tet10, Wedge6 and Hex8.
8 Local Mesh Controls The local mesh controls available are Mesh size on geometryBodyFacesEdgesRegions (with Break option)Mesh size on featuresFilletsCylindersWasherCircle ImprintValve Seat PocketIso-LineSeedingHard pointsFacesEdgesPreserve EntitiesFace EdgesFace shapeEdgeMeshSymmetry MeshMesh PatternsIsomeshFree MeshUnion Jack
9 Local Mesh Controls Following are the local mesh control parameters, Face Mesh ControlEdge Mesh ControlBody Mesh ControlFillet Mesh ControlCylinder Mesh ControlWasher Mesh ControlCircle Imprint Mesh ControlRegion Mesh ControlValve Seat Pocket Mesh ControlIso-Line Mesh ControlVolume Layer Mesh Control
10 1. Face Mesh ControlFace Mesh Control is used to control the mesh on the selected local faces. A uniform mesh is generated on the face that has the face mesh control specified.InputOutput Mesh
11 2. Edge Mesh ControlEdge seeds are applied either by specifying average element size or number of elements.Bias Seeding is used to seed an edge such that a constant ratio is maintained between adjacent bar elements. Edge Length will be in the following series:Lmin, Lmin * r, Lmin * r * r, . . .where, Lmin is the minimum edge length and r is the ratio.InputOutput Mesh
12 3. Body Mesh ControlBody Mesh Control is used to control the mesh on selected local bodies.All entities (faces and edges) present in the body, except the entities with other local mesh controls, will inherit this mesh control.InputOutput Mesh
13 4. Fillet Mesh ControlFillet Mesh Control is used to control the mesh over fillets along the length and the curve direction.InputOutput Mesh
14 5. Cylinder Mesh ControlCylinder Mesh Control is used to control the mesh both axially and radially on the selected cylindrical faces.InputOutput Mesh
15 6. Washer Mesh ControlWasher mesh control is used to create rings around a circle.The circle has to be inside one face.InputOutput Mesh
16 7. Circle Imprint Mesh Control Creates circular edge on a face with the specified radius and the number of seeds.InputOutput Mesh
17 8. Region Mesh ControlRegion mesh control applies local refinement within the defined shape (Cuboid / Cylinder) of region.The selected entities (faces/bodies) that lies inside the region will be assigned the specified size.Entities which are partially inside the region will be graded according to region of overlap.Also the region can break the face/body along the boundary of the chosen shape (Cuboid / Cylinder / Plane).The Plane option is used to Break the body or face.
18 8. Region Mesh ControlRegion Mesh Control -Cylinder – Local Size – Without BreakInput
19 8. Region Mesh ControlRegion Mesh Control -Cylinder – Local Size – Without BreakOutput
20 9. Valve Seat Mesh Control Valve Seat Mesh control is used to control the mesh in the valve seat pocket region. This controls the mesh on the cylinder and disc faces in the axial and radial direction and also preserves the chamfer faces if needed.
21 9. Valve Seat Mesh Control Valve Seat Mesh control without Preserve ChamferInputOutput
22 9. Valve Seat Mesh Control Valve Seat Mesh control with Preserve ChamferInputOutput
23 10. Iso Line Mesh ControlIso-Line Mesh control is used to control the mesh on cylinders and partial cylinders.It strictly maintains the axial mesh size and the angle.This separates iso-line mesh control from fillet and cylinder mesh controls.Reference point and direction is used to define the start point and the direction of the isomesh.Merge option is used to merge the selected faces.Reference point is also used to generate a mesh such that a radial shift of the iso- mesh is required.
25 11. Volume Layer Mesh Control Volume Layer Mesh control is used to generate layers of Tet elements along thin regions.The number of layers can also be specified in terms of the thickness of each layers. This option is useful when the number of layers have to change with the thickness for a body that has regions of variable thickness.
28 Hard Points – Mesh Control Hard points are used to create nodes at the specified point location on a face or an edge during meshing.Hard Points can be defined by selecting a point on the face/edges. In case of meshed body we can select nodes as hard point.InputOutput Mesh
29 Preserve EntitiesThe automated meshing process can collapse sliver faces. The mesher will automatically decide which one to preserve and which one to collapse.Using Preserve Entities mesh control, the user can control the features to be preserved while meshing.There are five types of preserve entities.Face ShapeFace EdgesEdgeSymmetry MeshMesh
30 Preserve Entities Face Shape This option is used to retain the planarity of the face after meshing. The nodes in the face will not get moved out of the face.Face EdgesThis option is used to retain all the edges of the face after meshing. This means that tiny edges on the faces will be preserved and the face will not get collapsed.EdgeThis option is used when only few edges of a face, are to be preserved when meshing.
31 Preserve Entities Symmetry Mesh This option is used to get identical mesh between the master face and symmetry face.If there are any discontinuous edges, then we need to pick three nodes/vertices in an order for both master and symmetry face.MeshThis option is used to maintain the existing mesh in the face during meshing.
32 Mesh Patterns Mesh Pattern The manner in which elements are arranged in a face is known as mesh pattern. The three types of mesh pattern available are,Iso-MeshThis create elements that have 2 edges almost 90 degrees and the diagonals are inclined in the same direction. This iso-mesh pattern can be created on a four sided surfaces.UnionJackThis create elements that have two edges almost 90 degrees and the diagonals are inclined in the opposite direction.Free MeshThis creates a mesh wherein, the mesh does not follow any pattern.
34 Local Mesh Controls Local mesh controls Select “Mesh Control” in meshing tool bar.This opens the “Mesh Control Parameters” dialog box.Select entities and enter values for the mesh control.Created “Mesh controls” are listed in the “Assembly Model” tree window under “Process Control” tab.
35 Modifying Local Mesh Control Whenever, a local mesh control is created, it is listed in the tree view.By double clicking the mesh control, the “Mesh Control Parameters” dialog box will open with all values set. These vales can be modified and saved.Select a face, right click and select “Local Meshing Parameters”. This opens the mesh control assigned to the selected face. This will work for bodies, faces and edges.
36 Mesh Control Specification Exporting a mesh controlThe Mesh control created can be saved in an external file, called "Mesh Specification" and the saved file can be imported back into SimLab. This is very useful when meshing models of similar types when the mesh control created for one can be reused for the others.
37 Mesh Control Specification Exporting a mesh controlThis has 4 options,TemplateMesh control parameters will be stored along with the geometry type associated with it, (like FACE, EDGE)Useful for assigning mesh control for models of the same typeBodyMesh control parameters will be stored along with the entity id.Useful for re-meshing the same model several times or the same model with small changes in the CAD file.
38 Mesh Control Specification Exporting a mesh controlColorMesh control parameters will be stored along with the color associated with it.Useful for assigning mesh control for models based on color.GroupsMesh control parameters will be stored along with the group name associated with it.Useful for assigning mesh control for models based on groups.
39 Mesh Control Specification Importing a mesh controlSelect a body to which the mesh control is to be assigned.Open the “Mesh Control Parameters” dialog box and select “Import File”Choose the mesh control file (with extension .xml).This will load all the mesh controls defined in the mesh control file.Go to the “Mesh Control” dialog box to see the imported mesh controls in the tree view.If template mesh spec is used, select bodies, faces, edges or features and assign it to the mesh control.
40 AutomationIt is common to find several cylinders with the same axis but separated by discs, cones or circular edges.It is sufficient to assign mesh control to one or part of a circular edge and all the edges will pick up the mesh seed.It is sufficient if the axial mesh size if assigned to one cylinder and all cylinders will pick it up.This transmission of the mesh size will stop if the circular disk separating the cylinders is too thick.