exercise 07: tet vs. hex meshing overview flangekmpkm.zut.edu.pl/pub/mes/nastran fx/tutorials...

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Exercise 07: Tet vs. Hex Meshing

Overview Flange

This example we will explore two mesh representations of the same solid model

- first build by tetrahedral and second by of hexahedral solid elements

- loads and constraints will be applied on model geometry

- hexahedral mesh will be generated for subdivided solid geometry

- NEi Nastran Engine will be used for model solution

01-21http://www.femdesign.pl A Member of FEMComp Engineering Group Tet vs. Hex Meshing

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Procedure

1. File, New…

2. Set Unit System to

N, mm, J, sec.

3. Click [OK] button.

4. File, Import, Geometry...

5. Open Flange.stp from NFX

training folder.

6. Uncheck Split Revolved

Shape.

7. Click [OK] button.

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Imported CAD Model Geometry

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http://www.femdesign.pl A Member of FEMComp Engineering Group Tet vs. Hex Meshing


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Procedure

8. Right Click in Work Window

and select [Hide Datum &

Grid].

9. File, Save command to save

NFX model with new name

Flange Tet.fnb in training

folder.

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Pressure load application

1. Run Analysis, Static Load,

Pressure...

2. Enter Pressure as Load Set.

3. Change Object Type to Surface.

4. Select the inner surface of the

flange

5. Enter -2 as uniform pressure (P)

6. Press [OK] to create a load.

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Model Constraints

1. Expand Geometry, Solid and right

click on Flange.stp:Solid 1.

2. Select Display Mode, Wireframe.

3. From Top Menu select Analysis,

Boundary Condition, Constraint…

command.

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1. Enter ”CS1” as the BC Set.

2. Change Object Type to Surface.

3. Select three surfaces as shown

4. Check T1 DOF and press [Apply].

5. Select bottom surface as shown.

6. Check T3 DOF and press [Apply].

7. Press [OK].

11. Change Flange Display Mode to

Shading with Edge again.

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Notice: T2 DOF assure Theta Symmetry of the model in Cylindrical Coordinate System. It will be explained later.

Model Constraints


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Model Material

1. At Model –Works Tree as below,

right click on Material and use Add,

Isotropic…

2. From material data base [DB <]

select AISI 1020.

3. Press [Close] button.

4. Click [OK] to set the material

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Geometry Mesh

1. From Top Menu select Mesh, 3D

Mesh, Auto Mesh Solid...

2. Select model solid part

3. Change Element Size to 3.

4. Click [OK].

5. Warning dialog box appears.

Press [OK].

6. In the Create/Modify 3D Property

dialog box press [OK].

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Mesh the Part 2/2

1. Type Tet Mesh as the Name of

the Mesh Set.

2. Press [OK] button to generate the

mesh. Your model should appear

like the following:

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Change Nodal CS to

Global Cylindrical

1. From Top Menu select Mesh,

Node, Change Sys...

2. Press [Displayed] button.

3. Set CS to Global Cylindrical.

4. Press [OK].

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Analysis Setup

1. From Analysis Works Tree select

Analysis and right click on Analysis

Case…

2. Pick Add and select Linear Static.

3. Once again right click on just

created.

4. Select Solve.

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Solver Manager dialog box appears, press [OK] (1) to run the analysis.

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Analysis Setup


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Results View

1. Select Post Data tab on Tabbed

toolbar.

2. Expand Data Filter and select

3D Element Stresses.

3. Set the Result Data Type to Von

Mises.

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1. Von Mises stress contour has

been displayed.

2. Select Solid Part and Right Mouse

click on Work Window. Select Hide

command.

3. From Menu Bar select Result,

Probe Result…

4. Attach a Probe Tags which

displays the result on the nodes

5.Save the model.

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3Results View


The model is subdivided into 9 independent solids and all parameters like Material, Property, Load and Boundary Condition are defined. You will create automatically hexahedral mesh.

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Open new geometry

1. From Menu Bar open Flange

Hex. fnb from NFX training

folder.

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15-21http://www.femdesign.pl A Member of FEMComp Engineering Group Tet vs. Hex Meshing


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Model Hex Mesh

1. From Top Menu run Mesh, 3D

Mesh, Auto Mesh Solid...

2. Press [Displayed].

3. Enter 2.5 as Element Size.

4. Click [Advanced Option].

5.Check on - Try Mapped Mesh,

Match Adjacent Faces, Skip

Failed Solid(s),

6. Check off Generate Mid-Side

Nodes

7. Press [OK].

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Mesh the Part 2/2

1. Type Hex Mesh as the Name

of the Mesh Set.

2. Press [OK] button to generate

the mesh. Your model should

appear as below.

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Merge Nodes, Set Nodal

CS to Global Cylindrical

1. From Mesh Menu use

Mesh, Node, Merge...


3. Press [OK].

4. From Menu Bar select

Mesh, Node, Change Sys...


6. Set CS to Global Cylindrical.

7. Press [OK].

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Setup the Analysis

1. In Analysis Works Tree right click

on Analysis Case…

2. Select Add and select Linear

Static.

3. Once again right click on just

created.

4. Select Solve.

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Setup the Analysis

1.From Menu Bar select Analysis,

Solve… command.

2. Solver Manager dialog box

appears.

3. Press [OK] to run the analysis.

4. After calculations select Post

Data tab on Tabbed toolbar.

5. Expand Data Filter and select

3D Element Stresses.

6. Set the Result Data Type to Von

Mises.

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View Results

1. Von Mises stress contour has

been displayed.

2. Select Solid Parts and Right

Mouse click on Work Window.

Select Hide command.

3. From Menu Bar select Result,

Probe Result…

4. Attach a Probe Tags which

displays the result on the nodes.

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exercise 07: tet vs. hex meshing overview flangekmpkm.zut.edu.pl/pub/mes/nastran fx/tutorials...

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