Download Solid Meshing Techniques

WORKSHOP 9
Solid Meshing Techniques
Objectives
■
Create solid geometry.
■
Create surface meshes.
■
Create solid mesh with Automesher.
9-1
MSC.Nastran for Windows 101 Exercise Workbook
WORKSHOP 9
Solid Meshing Techniques
Model Description:
The purpose of this exercise is to create two solid geometries (an
assembly) and obtain a unified mesh of both parts.
Figure 9.1
9-2
MSC.Nastran for Windows 101 Exercise Workbook
MSC.Nastran for Windows 101 Exercise Workbook
9-3
WORKSHOP 9
Suggested Exercise Steps:
Solid Meshing Techniques
Exercise Procedure:
■ Define materials.
1.
Start up MSC.Nastran for Windows V4.0 and create a new model.
■ Define planar and solid properties.
Double click on the icon labeled MSC.Nastran for Windows V4.0.
■ Create a solid box.
Open Model File:
■ Create a surface for extrusion.
■ Extrude the surface to create a solid extrusion.
2.
New Model
Create two materials.
■ Intersect the two solids to obtain a common interface.
Model/Material...
■ Apply mesh controls to interface surfaces.
Title:
mat_1
■ Mesh surfaces.
Youngs Modulus:
10e6
■ Create curves and project onto the solid box.
Poisson’s Ratio:
0.3
■ Extrude planar elements to get solid mesh.
OK
Title:
mat_2
Youngs Modulus:
30e6
Poisson’s Ratio:
0.3
OK
Cancel
3.
Create three properties. The “Plot” type elements will only be used to
generate a dummy surface mesh. This dummy surface mesh will be used
to generate solid, tetrahedral elements and to extrude into penta
elements.
Model/Property...
Elem/Property Type...
Plane Elements:
● Plot Only
OK
plot
Title:
OK
9-4
MSC.Nastran for Windows 101 Exercise Workbook
MSC.Nastran for Windows 101 Exercise Workbook
WORKSHOP 9
9-5
Solid Meshing Techniques
When asked OK to Create?
View/Autoscale <Ctrl+A>
Yes
View/Select... <F5>
Render
Elem/Property Type...
Volume Elements:
OK
● Solid
OK
6.
Title:
prop_1
Material: (pulldown)
1..mat_1
Create an extruded solid on Surface 1 of the original box.
Shift the workplane to Surface 1:
Right Click on screen.
OK
Title:
prop_2
Material: (pulldown)
2..mat_2
Workplane...
Refer to the following figure for location surface and points of the cube.
Figure 9.2
OK
Cancel
4.
Create a 1 x 1 x 1 box.
Geometry/Solid/Primitives...
Title:
box
Material:
● New Solid
Surface 1
OK
5.
Get an isometric view of the box.
Click the Dynamic Rotate toolbar button.
Rotate the view with the Left Mouse Button to get an isometric view.
When done:
OK
9-6
MSC.Nastran for Windows 101 Exercise Workbook
Point 2
Point 1
Define Plane:
On Surface...
On Surface:
1
At Point:
2
Axis Point:
1
MSC.Nastran for Windows 101 Exercise Workbook
9-7
Solid Meshing Techniques
WORKSHOP 9
First Quadrant
Figure 9.3
OK
Curve 13
View/Autoscale <Ctrl+A>
Point 11
Geometry/Curve - Arc/Angle-Center-Start...
Methods^
Point 9
Locate in Workplane
Curve 14
Center of Arc
X:
Y:
0.5
0.5
OK
Start of Arc
X:
Y:
0.75
0.5
OK
OK
90
Angle:
Geometry/Surface/Ruled...
OK
Cancel
14 (newest curve)
To Curve:
13 (first curve)
OK
Geometry/Copy/Curve...
Cancel
Select the previously created curve
13
ID:
From Curve:
Geometry/Solid/Extrude...
OK
OK
Right Click on screen.
Material:
● New Solid
Direction:
● Negative
To Depth:
0.5
Surface...
Snap to Point
7 (newly created surface)
ID:
In the Vector Locate form, screen-select the following points.
9-8
Base:
Point 11 (midpoint of arc)
Tip:
Point 9 (center point of arc)
OK
OK
MSC.Nastran for Windows 101 Exercise Workbook
MSC.Nastran for Windows 101 Exercise Workbook
WORKSHOP 9
Figure 9.4
Solid Meshing Techniques
Figure 9.5
8.
7.
9-9
Break the surface of the box at the interface with the extruded solid. This
step is necessary to ensure congruent mesh between the two solids.
Specifiy mesh seeding on the interface.
Mesh/Mesh Control/Size on Surface...
(Select the two surfaces at the interface.)
Geometry/Curve - From Surface/Update Surfaces
Geometry/Curve - From Surface/Intersect...
Entity Selection:
Select First Surface for Intersection (actually the solid)
OK
ID:
Cancel
1 (the box)
OK
+14, +13
OK
(use default element size)
Figure 9.6
Select Second Surface for Intersection (actually the solid)
ID:
3 (the extruded solid)
OK
Cancel
View/Autoscale <Ctrl+A>
9-10
MSC.Nastran for Windows 101 Exercise Workbook
MSC.Nastran for Windows 101 Exercise Workbook
9-11
Solid Meshing Techniques
WORKSHOP 9
9.
Mesh the interface making sure their meshes coincide.
10.
Create mesh controls for the solids.
Mesh/Geometry/Surface...
Mesh/Mesh Control/Size on Solid...
(Select the two surfaces at the interface.)
Entity Selection:
(Select the first extruded solid.)
+14, +13
Entity Selection:
OK
+3
OK
Property: (pulldown)
1..plot
Element Shape:
● All Triangles
● Tet Meshing
OK
OK
(use default element size)
Mesh/Mesh Control/Size on Solid...
Zoom in on the mesh to take a closer look. Click the Zoom toolbar button
and drag a box:
(Select the 1 x 1 x 1 box.)
Entity Selection:
+1
OK
● Tet Meshing
The meshes should coincide. When done:
OK
(use default element size)
View/Autoscale <Ctrl+A>
Figure 9.8
Figure 9.7
9-12
MSC.Nastran for Windows 101 Exercise Workbook
MSC.Nastran for Windows 101 Exercise Workbook
9-13
Solid Meshing Techniques
WORKSHOP 9
11. Mesh the solids.
OK
Mesh/Geometry/Solids...
When asked “OK to Specify Additional Range of Nodes to Merge?”,
answer No.
(Select the 1 x 1 x 1 box.)
Entity ID:
1
No
OK
Merge Coincident Entities
OK to Update Mesh Sizes?
OK
No
Property: (pulldown)
2..prop_1
13.
Get a better view of the model.
Right Click on screen.
Uncheck Midside Nodes.
Workplane...
Midside Nodes
Uncheck Draw Workplane.
OK
Draw Workplane
Mesh/Geometry/Solids...
Done
(Select the first extruded solid.)
Entity Selection:
+3
View/Autoscale <Ctrl+A>
Click the View Style toolbar button.
OK
OK to Update Mesh Sizes?
No
Property: (pulldown)
3..prop_2
Uncheck Midside Nodes.
Rendered Solid
Click the Quick Options toolbar button or <Ctrl+Q>.
Midside Nodes
OK
Turn off Node.
NOTE: When meshing solids with plate elements on the faces, the solid
mesher will automatically match tet-elements to the triangular face
elements.
Node
Geometry Off
12. Check for coincident nodes and merge them.
Done
Tools/Check/Coincident Nodes...
Select All
9-14
MSC.Nastran for Windows 101 Exercise Workbook
MSC.Nastran for Windows 101 Exercise Workbook
9-15
Figure 9.9
14. Save your model.
File/Save As...
Filename:
solid_mesh
Save
This concludes the exercise.
File/Save
File/Exit
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MSC.Nastran for Windows 101 Exercise Workbook