HM-3210: Creating a Hex-Penta Mesh using Surfaces fil e : / I I C : I Pr ogram Fi I e s/Al tairl 1 1 . 0i he I p I hw fi/ hn$21 0.hrrn

HyperWorks Tutorials

HM-3210: Creating a Hex-Penta Mesh using Surfaces

ln this tutorial, you will learn how to:

. Create solids using different functions

. Check and fix improper model connectivity

For some analyses, it is desirable to use a mesh of hexahedral and pentahedral elements. This is especially true for partswhich have a large thickness compared to the element size being used, or for parts that have many features and/or changes inthickness. Castings or forgings are good examples.

Exercise: Creating a Hex-Penta Mesh using SufacesThis exercise uses the model file, arm bracket. hm. This exercise introduces you to a number of HyperMesh functions thatare used to create hexa-penta meshes. The model is organized into four IGES layers, consisting of 1) the base, 2) the firstsection of the arm, with a constant cross section and curvature, 3) the second section of the arm, with a tapered crosssection, and 4) the boss.

r-

'-I

-_l-n+

Step 1r Retrieve and review model file.Open the arm_bracket. hm file.

step 2: Mesh the top surface of the base, including the L-shaped surface.1. Set the active component collector to base using the HyperMesh Model Browser. ln the Model Browser right-click base

and select Make Current.

2. While in the F{yperMesh Model Brovvser, hide all components except the base component.

3. Access the Automesh panel from the menu bar by selecting Mesh > Create > 2D Automesh.

4. Select the surfaces on the top of the base, including the L-shaped surface at the intersection of the base and the arm.For this part of the exercise it might be easier to view the geometry in a shaded mode by clicking Shaded Geometry and

filSurface Edges (Y 1.

5. Select the size and bias subpanel.

6. Set the meshing mode to automatic.

t"-t."

I

I

Il

t

- *:;:t.".'"",.

1.

i\+I

iIj

iI

l of l1 9115120113:17 AM

HM-3210: Creating a Hex-Penta Mesh using Surfaces fi,le l I lC:lProgram FilesiAltair/ I 1 .0/help/hwtut/hm32l 0.htm

7. For element size = specify 10.

8. For element type specify quads only.

9. Click mesh to mesh the surfaces.

,l'u,- | _-t-

gi{

Resulting quad mesh on base surfaces

10. Click return to return to the main menu.

You can now change back to an unshaded view for the geometry.

Step 3: Create layers of hex elements for the base.

1 . Go to the Elem Offset panel by selecting M esh > Create > 3D Elements > Element Offsef from the menu bar.

2. Select the solid layers subpanel.

3. With the elems selector active under elems to offset, select the elements on the base.

4. For number of layers = specify 5.

5. For total thickness = specify 25.

6. Click offsef+.

The hexa mesh is created.

Step 4: Prepare the display for meshing the arm's curved segment.1. Turn on the display of the arm_curve component using the HyperMesh Model Browser.

2. Press the F5 key to go to the Mask panel.

3. Select elemenfs >> by config, and select the hex8 configuration.

2ofll 9115120113: l7 AM

HM-3210: Creating a Hex-Penta Mesh using Surfaces file : I I I C : I Pr ogam F i I es/Altair/ 1 I . 0/help/hwtut/hm3 2 1 0.htrn

Click se/ecf entities.

All of the elements with a configuration of hexS in the model are selected

Click mask to mask the elements.

Click return to return to the main menu.

Step 5: Create a node at the center of the arm radius.

The first segment of the arm can be meshed using the Spin panel. This requires a node to be selected as the center point ofrotation. The node you create in this step will be used as that center point. To create the center node, you will use thedistance / 3 nodes subpanel.

1. Press the F4 key to enter the Distance panel.

2. Go to the three nodes subpanel.

3. With the A/1 selector active, create the temporary nodes on one of the curved lines of the arm as described below:

. Press and hold the left mouse button.

. Move the cursor over a curved line.

. Once over the line, the cursor will change to a square with a dot in the center, l:, anO the tine will be highlighted.Release your mouse button.

4. Click three locations along the selected line. The active selector advances from N1 to IV2 to A/3, and the locations will beselected as though there was a node there.

5. Click circle centerto create the node at the center.

This node will be used in the next step when you mesh the arm.

Cr€at€ thrEs ndes m *nyo,f th€ c[fved hnes afld thfrlselect cr'rd* csrr?'t* to lirdthe center.

.r, _=+1

I

Three nodes to create a center node

6. Click return to return to the main menu.

Step 6: Create hexa elements in the curved portion of the arm using spin.1. Set arm_curve as the current component using the HyperMesh Model Broririser.

2. Go to the Spin panel by selecting Mesh > Create > 3D Elemenfs > Spin from the menu bar.

3. Select the spin elems subpanel.

4. Using elems >> by window, select the plate elements within the L-shaped cross section of the arm.

5. Click select entities.

5.

8.

Cenicr

*/

3ofll 9l15/2011 3:17 AM

HM-3210: Creating a Hex-Penta Mesh using Surfaces

6.

7.

8.

9.

Elements to select for spin function

For angle = specify 90 degrees.

For the direction, select the x-axis (Y-Z plane).

For the base node (B), click the center node created in step 5.

For on spin = specify 2 4 .

24 layers of hex elements will be created when the plate elements

frle : I I I C : I P r ogram F i I e s/Altair I I 1 .0 I help I hw E:[l hm3 2 I 0. htm

are spun.

10. Click spin -.

11. Click return to return to the main menu.

Step 7: Create faces on the hex elements.

1. Go to the Faces panel by selecting Mesh > Check > Compenenfs > Faces from the menu bar.

2. With the entity selector set to comps, select the arm_curve component.

3. Click find faces.

2-D shell elements are created on the free faces of every 3-D solid element in the component. They are placed in a newcomponent named ^faces.

4of1l 9115120113:17 AM

HM-3210: Creating a Hex-Penta Mesh using Surfaces file: I I I C: lProgram FilesiAltair/ 1 1 .0/helplhwtut/hn32l 0.htrn

The ^faces component is created with its visualization set to wireframe, so you will not be able to see the new elementsright away if the arm_curve component is displayed and in shaded mode.

4. On the toolbar click Shaded Elements & Mesh Lines 1*; to shade the elements.

You will now see the elements in the ^faces component.

Step 8: Prepare the display for meshing the second arm segment.

1. Use the Model Browser to turn on the display for the arm_straight and ^faces components.

Step 9: Mesh the L'shaped set of surfaces between the arm straight and boss components.1. Set the current component collector to arm_straight.

2. Go to the Automesh panel.

3. Select the three surfaces lying on the intersection between the arm_straight and boss components.

These surfaces are in the arm_straight component.

4. Set the meshing mode to interactive.

5. Click mesh to go to the meshing module.

6. From the Density subpanel, adjust the densities to obtain a mesh that matches the following image.

This mesh pattern matches the mesh pattern at the intersection of the two arm segments. This is necessary for the nextstep.

''!

Densities to correspond to the mesh on the end face

7. Click mesh to update the mesh density.

8. Click return to create the elements and go back to the Automesh panel.

9. Click return to return to the main menu.

Step 10: Use linear solid to build the mesh between the two sets of shell elements.1. Access the Linear Solid panel through the menu bar by selecting Mesh > Create > 3D Elements > Linear 3D.

2. With the from: elems selector active, select the ^faces elements lying on the intersection between the first and secondarm segments.

You can select one of the elements and then select elems >> by face to select the rest of the necessary elements.

5 of l1 9l15l201l 3:17 AM

HM-3210: Creating a Hex-Penta Mesh using Surfaces file : I I I C: I Pr ogram Files/Altairi 1 1 . 0/hel p lhw nl/./ hn321 0.htm

Click the to: elems selector to make it active. Then select the shell elements between the arm and boss, which youcreated using the Automesh panel in the last step.

Click the from: alignment: N1 selector to make it active. Then select three nodes on one of the "from elements" youselected in sub-step 10.2.

Click the to: alignmenf.' Nl selector to make it active. Then select three nodes on the "to element" corresponding to the"from element" with the three "from nodes" you selected in sub-step 10.4. Refer to the following image.

Hodes for #2

I --. Hodes for #3tr

il

T

I

\/ 'q,7

Example selection for alignment nodes

For density = specify 12.

Click solids to create the mesh.

3.

4.

6.

7.

'".i'I

- ---- ---- - - ':': ..-:

Il

!

!

,

IF

I

n\t I_v-

Linear solid mesh

8. Click return to the main menu.

Step 11: Prepare the display for meshing the boss.

1. Use the HyperMesh Model Browser to show the boss component.

6ofll 911512011 3:17 AM

HM-3210: Creating a Hex-Penta Mesh using Surtaces

Step 12: Create a shell mesh on the bottom of the boss.

1. Set the current component collector to boss.

2. Go to the Automesh panel.

3. Select the five surfaces on the bottom face of the boss.

4. Click mesh to go to the meshing module.

5. Adjust the densities to match the following image:

Mesh densities on the bottom of the boss

6. Click mesh to update the mesh density.

7. Click return twice to return to the main menu.

Step 13: Project a node to the bottom face of the boss.

1. Go to the Project panel by selecting Mesh > Project > A/odes from the menu bar.

2. Select the to line subpanel.

3. Select the node on the rightmost top vertex, as per the following image.

4. Click nodes >> duplicate.

5. For the to line select the line on the boss' top face. Refer to the following image.

fil e : I I I C: I Pr ogram Fi I esiAltairl 1 I . 0/hel p lhw nilhrr02l 0.htrn

Tofll 911512011 3: l7 AM

Selectthis node and Iine.

HM-3210: Creating a Hex-Penta Mesh using Surfaces file: / I I C: lProgam Files/Altair/ I 1.0/helplhwhn/hn32l 0.htrn

Projecting a node to a line

6. Select along vector: x- axis.

7. Click project to project the node to the line.

8. Click return to return to the main menu.

Step 14: Generate hexas for the boss using the Solid Map panel.

1. Go to the Solid Map panel by selecting Mesh > Create > Solid Map Mesh from the menu bar.

2. Go to the general subpanel.

3. Select source geom: (none).

4. Select desf geom: surf and select the top surface of the boss.

5. Select along geom: mixed.

6. Under along geom: mixed, click lrnes to make it the active selector.

7. Select the line indicated in the following image.

8. Click node path to make it the active selector.

9. Select nodes to define the exact location of the solid element layers, as indicated in the following image.

Atotal of 13 nodes should be selected, starting at the boss mesh, and then using all of the nodes along the edge of thearm_straight component, ending with the node projected to the top of the boss.

8 of ll 9115120113:17 AM

HM-3210: Creating a Hex-Penta Mesh using Surfaces fil e : I I I C : I Pr ogam Fi I e s/Altair/ 1 l . 0ihe lp/hwnrVhm3 2 1 0.htrn

Select these nudes inorder, fro hottom to top.

Select this line.

Along nodes for solid map

10. For elemsto drag.', select elems >> by collector and select the boss component

11. Click mesh.

The elements are created and the mesh on this part is completed.

il

I_t

-ytCompleted mesh of the arm bracket

12. Click return to return to the main menu

Step 15 (optional): Check the connectivity of the model.

1. Go to the Faces panel.

2. Click comps to go to a list of components.

3. Select every component from the list, or select comps >> all.

4. Click Selecf complete the selection and go back to the Faces panel.

9of1l 911512011 3:17 AM

HM-3210: Creating a Hex-Penta Mesh using Surfaces ftle : I I I C: I P r osam F i I es/Altair I I 1. O/he lp/hwtut/hm3 2 I 0.htm

5. Click find faces.

6. Turn off the geometry display of all components via the Model Browser.

7. Turn off the element display of all components except ^faces.

8. Click return to exit the the panel.

9. On the Post page go to the Hidden Line panel.

10. Activate the xz plane and trim p/ane options.

11. Click show plot.

The faces are now displayed with a plane cutting the model in half. This is so that the interior of the model can be viewed.

12. Click near the cutting plane. Holding the left mouse button down, move the mouse back and forth.

The cutting plane moves through the model, allowing you to see if any face elements exist on the interior of the model.You should see that there are face elements interior to the model, between the boss and arm. You need to perform somecorrections on the connectivity.

l Face elements -----inlerior to the model

Hidden line viewof faces

13. Click return to return to the main menu.

Step 16 (Optional): Correct the connectivity of the model.1. Display elements for all components except for the ^faces component.

2. Display the elements of the solidmap component as transparent.

3. Go to the Faces panel.

4. Select elems >> displayed.

5. Click preview equiv.

Coincident nodes on the intersection between the arm and the boss are highlighted.

6. Specify a slightly larger value lor tolerance =, and click preview equiv to identify more coincident nodes on theintersection.

7. Repeat sub-step 16.6 until all 60 coincident nodes have been found.

8. Click equivalence.

The nodes are replaced to the location of the lowest node lD.

9. Switch all the components to the shaded visual mode.

10 of 11 911512011 3:17 AM

HM-3210: Creating a Hex-Penta Mesh using Swfaces

Step l7 (Optional): Recheck the connectivity of the model.Repeat Step 15 to make sure the model is now equivalenced. lf you find errors, repeat Step 16.

Step 18 (Optional): Save your work.

The 3-D solid mesh has now been completed. Save the model if desired.

Go to HvperMesh Tutorials

file: / / /C: lkogram Files/Altair/l 1.0/help/hwhn/trn32 I O.hrn

l1 of 11 9/15120113:17 AM