3 Solid Mesh

BETA CAE Systems S.A.

Tutorial 3

SOLID MESHING FOR

STRESS ANALYSIS

TETRA & HEXA MESH

Table of Contents

3.1. Introduction .................................................................................................................................2 3.1.2. Prerequisites .......................................................................................................................2 3.1.3. Problem description.............................................................................................................2 3.1.4. Data files .............................................................................................................................2

3.2. Read the ANSA database ...........................................................................................................3

3.3. Generate the tetra Volume Mesh................................................................................................4

3.4. Identify poor quality regions of the volume mesh........................................................................7

3.5. Generate a good quality triangular surface mesh .......................................................................9

3.6. Remesh the volume ..................................................................................................................20

3.7. Obtain information about the mesh. ..........................................................................................21

3.8. Obtain information about the component ..................................................................................24

3.9. Prepare the geometry for Hexa meshing ..................................................................................26

3.10. Create the interior Faces of the sub-volumes .........................................................................43

3.11. Generate the Quad Surface mesh ..........................................................................................50

3.12. Generate the Hexa Volume Mesh...........................................................................................78

3.13. Examine and improve the quality of the Volume Mesh...........................................................83

3.14. Conclusion ..............................................................................................................................84

SOLID MESHING FOR STRESS ANALYSIS Tetra & Hexa mesh

BETA CAE Systems S.A. Tutorial 3 - 2 ANSA v.12.0.1 Tutorials

3.1. Introduction

This tutorial presents in detail all the steps taken to generate one tetra and one hexa mesh for the same component. You will read an ANSA database containing the geometry of the component create a tetrahedral mesh, and then read again the same file in order to create the hexa mesh.

The steps described in this tutorial are:

Read the ANSA database of the component.

Generate the triangular surface mesh for the tetra solid mesh.

Examine and improve the quality of the surface mesh.

Define the closed volume that will be meshed.

Generate the tetra elements.

Examine the quality of the volume mesh.

Obtain information regarding the mesh (number, quality) and the component (weight, volume)

Read the same ANSA database to mesh it from the beginning with hexa elements.

Prepare the geometry for hexa meshing, by cutting it into blocks.

Align the nodal number of the Perimeter Segments.

Create a surface mesh of quad elements only.

Generate the hexa elements using the Volume Map algorithm.

Examine and improve the quality of the volume mesh. Note that the hexa mesh requires more effort and time than the tetra mesh. Both of them though will familiarize you with many ANSA functionalities.

3.1.2. Prerequisites

Reading the 4 pages of section Intro.2.1. Getting Started of this Guide is recommended in order to obtain a familiarization with the ANSA interface and terminology. It is also suggested to have performed Tutorial 1.

3.1.3. Problem description

The geometry of the component is shown below:

3.1.4. Data files

The file required for this tutorial is tutorial_files/03-solid_mesh/solid.ansa . The

results can be found in files solid_tetra.ansa and solid_hexa.ansa in the same directory

for reference.



3.2. Read the ANSA database

Start ANSA. In this case you will read an ANSA database with clean geometry and no topological problems. Keep the default middle tolerance settings in the SETTINGS>TOLERANCES function.

Select FILE>OPEN to read the ANSA file.

The File Manager window appears. Specify a filter (*ansa in this case),

navigate and select the ANSA file solid.ansa.

Press OK. The geometry of the part is read into ANSA.

The part should appear as shown.

Activate SHADOW display mode and rotate

the part to view it better.

You can perform a quick check of the topology by de-activating SHADOW mode and DOUBLE CONS visibility flag buttons. The display is left blank which implies that there are no free (red) or triple (cyan) CONS and hence this is the description of a closed volume. Activate SHADOW and DOUBLE flag buttons back.

Save the file as solid.ansa in your local directory from FILE>SAVE AS.

SHADOW



3.3. Generate the tetra Volume Mesh

Switch to MESH menu.

Switch to WIRE display mode de-activating SHADOW.

Before proceeding to volume meshing, you should ensure that the correct element length and distortion settings are assigned to all Perimeter Segments.

Activate the SHELL MESH> PARAM. and ensure that the

Element Length minimum limit is set to zero.

Activate the MACROs>LENGTH function. Select with left mouse

box selection all the Macro Areas. Confirm with middle mouse button. The Input window appears.

The element length is applied on all the Perimeter Segments of the selected Macro Areas.

Finally activate the PERIMETERs>DISTOR function.

The Distortion Definition window appears. Specify a distance distortion of 20% of the local element length.

Press OK to apply these settings on all the visible Perimeter Segments. Note that the appearance of the model has not changed. This is because the values of length and distortion were already applied in the ANSA database that you opened.

However it is advised to always check these parameters.

In order to mesh the component with tetra elements you must first define the Volume entity.

Activate the VOLUMEs>DEFINE function. Keep the Auto flag

active in the Mode window. Left click on one of the Macros that form the volume. The Auto mode recognizes and selects all the Macros that form a closed volume. Press middle mouse button to accept.

DEFINE

DISTOR

MESH >

WIRE

PARAM.



The Properties window appears so that you can assign a Property for the solid elements that will be generated. As there is no available Property in the list click on NEW to create one. A new Solid Property card appears. (Note the appearance of the card depends on the currently active Deck, which in this case is NASTRAN). Click OK to accept the default values.

Back to the Properties window, the newly created Property is highlighted in black. Double click on it in order to select it.

Next, the Part Manager appears, in order to allocate the Volume entity to a Part. Select NEW [PART] to create a new Part. A new empty Part appears in the Part Manager.

Click on the name and change it to "volume".

Then left click on the new part to place the Volume entity in it.""

Make sure that the VOLUM. Visibility flag button is active,

otherwise you cannot see or select a Volume entity.

To verify the Volume entity creation, activate the

VOLUMEs>INFO function and pick the Volume. This becomes highlighted for a preview. Press ESC to exit.

INFO

VOLUM.



Before meshing the Volume, activate the VOLUMEs>PARAM

function to adjust the meshing algorithm parameters. The Tetra Meshing Parameters window appears. Change the Maximum Growth rate from 1.2 to 1.0, so that the generated elements do not grow in size towards the interior of the Volume. Select IDEAS stretch and specify a guiding limit of 0.5. Press OK to close.

To generate the tetra mesh activate the VOLUMEs>MESHV [TET MESH] function

and select the Volume with the left mouse button. Confirm with middle mouse button.

As the Macros Areas were unmeshed the FREE TRIA algorithm is applied to all of them by default, to generate a starting surface mesh.

Then the volume mesh generation process

begins. A progress bar appears as well as messages in the Text Window.

2904 triangular elements are generated on the surface and 16829 tetra elements in the volume, as reported in the text legend on the bottom left of the display. (Note that the number of generated elements may vary between different machines due to round off).

De-activate the MACROs visibility flag to remove the Macro

Areas from the view. Only the tetra volume elements remain visible.

Save the file as solid_tetra.ansa from FILE>SAVE AS.

PARAM

TET MESH

MESHV

MACROs



3.4. Identify poor quality regions of the volume mesh

The quality of the surface and volume mesh will be examined with respect to skewness criteria.

Activate the Presentation Parameters window by pressing the F11 key. Keep only the Skewness flag button active and then select the IDEAS

skewness definition. Input a threshold value of 90 degrees for shells and 0.4 for solids.

Ensure that you have the default threshold values shown for quality criteria (min, max elem. length =0) as they affect the surface mesh generation process. In case that these were not the values used in the previous step erase and remesh the model. De-activate the Middle Point Dev and Align. flags at the bottom. Press the OK button to accept the settings and exit.

To perform the quality check switch to HIDDEN view mode by

activating the respective flag.

Elements that violate skewness quality criterion are colored in green according to the legend on the right. The number of visible violating elements, 9 in this case, is shown on the left under OFF.

Note that the number of OFF elements may vary slightly between different machines due to round off. As a result the following steps of shell mesh improvement may have to be performed in different areas.

Activate the EXTREME function of the FOCUS group to isolate the

violating tetra elements.

(Note that MACROs visibility flag is de-activated and hence only failed tetras are visible).

! Note also that from ANSA v11.3.1. the EXTREME function can zoom automatically to the worst element (see ANSA Users Guide section 9.5.3.1.).

The following steps are optional and are performed in order to mark the positions in space of the problematic tetra elements. This will allow a clearer observation of their locations with respect to the surface mesh.

F11

HIDDEN

EXTREME



Switch to TOPO menu.

You are going to create 3D Points at the locations of the tetra elements.

Make sure that the POINTs visibility flag is active so that you

can see the Points that you will create.

Activate the POINTs>RELAT. function. Select with left mouse

button box selection all the nodes of the violating tetra elements.

Confirm selection with middle mouse button.

The Relative window opens. Keep the default zero values and press OK to create the 3D Points at the selected positions.

The created 3D Points appear as cyan squares.

Switch back to MESH menu.

De-activate HIDDEN display switching to WIRE to be able to

see inside the outer surface mesh.

Activate MACROs visibility again to bring the surface mesh back.

You should be able to see the surface mesh and the violating tetra elements marked by cyan 3D Points. Rotate the part to examine them better. Notice that all OFF tetra elements are near the surface.

To avoid such elements you should focus on the generation of a good quality surface mesh first.

Activate the SHELL MESH> ERASE [Visible] to erase the surface mesh of all the visible Macro Areas.

Notice that as a consequence the volume mesh is erased automatically, due to its dependency to the surface mesh. Note however that the Volume entity remains valid even if unmeshed.

(Notice that the 3D Points remain still visible. You can switch back to TOPO and de-activate the POINTs visibility flag button.)

TOPO >

RELAT.

MESH >

WIRE

POINTs

MACROs

Visible

ERASE



3.5. Generate a good quality triangular surface mesh

Now you will focus on the generation of a good quality surface mesh to guarantee a volume mesh without problematic tetra elements.

Switch to SHELL MESH> TRIA switch button position to generate triangular shell elements.

Activate the SHELL MESH>FREE [Visible] function to mesh all visible Macro Areas with the FREE

algorithm.

All Macro Areas are meshed as reported in the Text Window. The number of generated elements is displayed at the bottom left of the screen.

To perform the quality check switch to HIDDEN view mode by

activating the respective flag. Elements that violate skewness quality criterion are colored in green according to the legend on the right. The number of visible violating elements, 29 in this case, is shown on the left under OFF. Note that the number of generated and OFF elements may vary slightly between different machines due to round off. As a result the following steps of shell mesh improvement may have to be performed in different areas.

The improvement of the mesh will be made in two steps. The first and most important consists of the improvement of the shape of the Macro Areas, the application of different meshing algorithms, and the adjustment of the nodal number of selected Perimeter Segments. These actions will eliminate most of the problematic elements. The second step will consist of movement of nodes on the CAD geometry, and element splitting in order to improve the quality of the remaining violating elements.

Zoom in to the location shown in the small image.

You can see a very narrow Macro Area with highly skewed elements.

Activate the MACROs>JOIN function and select with left

mouse button the Perimeter Segment shown.

Note that to retrieve a Perimeter Segment, that was joined unintentionally, activate the MACROs>RELEASE function and select it among the previewed Segments with the left mouse button.

JOIN

Visible

FREE

HIDDEN

MIXED

QUAD

TRIATRIA

MIXED..



The Perimeter Segment is removed and the two neighboring Macro Areas are joined to form a wider one. Their mesh is erased.

While still in the same function select the other four Perimeter

Segments shown, so that they are also joined.

The mesh of the affected Macros is erased.

Activate the HOT POINTs> DELETE function and select the

leftover Hot Points to delete them.

As the Hot Points are deleted from the Perimeters, the Perimeter nodes are recalculated and therefore the mesh is again erased.

Activate the SHELL MESH> RE-MESH [Visible] function to remesh all the visible unmeshed Macros with the

algorithm that was last used for each one (in this case the Free Tria).

! Note that from ANSA v11.3.1. the SHELL MESH> A.MESH function allows the automatic remeshing of Macros which were erased by such modifications (see ANSA Users Guide section 9.4.3.).

Notice that not only the violating elements have disappeared, but also the overall look of the mesh has improved.

DELETE

Visible

RE-MESH

JOIN



Move to the next area. There is one skewed element. Try using a different meshing algorithm for this Macro Area.

Erase the current mesh of the Macro using the SHELL MESH>ERASE [Select] function. Left click on the

Macro and press middle mouse button to confirm selection.

The selected Macro is highlighted.

Note that to de-select an unwanted Macro, right-click on it. Use the SHELL MESH>RE-MESH function to remesh an erased Macro.

Confirm selection with the middle mouse button.

Use the SHELL MESH> GRADUAL [Visible] function to mesh the single unmeshed Macro with the Gradual

algorithm.

Notice how the resulting mesh differs from the previous one. The Gradual algorithm produces more elements than the Free, and thus avoids some skewed elements.

! Note that from version 11.3.0 the [Re-Generate] option is available in all meshing functions and there is no need to erase the current mesh to try a different algorithm (see Users Guide section 9.4.2.).

Select

ERASE

Visible

GRADUAL



Move to the next area. Here although there are no violating elements there is a short Perimeter Segment that interrupts the flow of the mesh.


mouse button this Perimeter Segment.

Activate the HOT POINTs> DELETE function and select with

a box the leftover Hot Points to delete them.

The mesh is erased.

Activate the SHELL MESH> RE-MESH [Visible] function to remesh all the visible unmeshed.

JOIN

DELETE

Visible

RE-MESH



Moving upwards to the next region, notice that there is a problem inside the hole.

To view the inner Macros of the hole, perform a NOT operation

from the FOCUS Group of commands, and select with box selection the Macros that you want to remove form the view.

To further isolate the region, perform an OR operation and

select with box selection the Macros of interest.

Only the eight Macro Areas remain visible.

Zoom closer to view the mesh better.

Again here you can join some Perimeter Segments, to improve the quality of the generated mesh.


mouse button the Perimeter Segment shown.

NOT

OR

JOIN



The mesh is locally erased and a wider Macro is formed.

Join the remaining three intermediate perimetrical

Segments with the JOIN function.

Now you can also delete the left over Hot Points.

Activate the HOT POINTs> DELETE function and perform a

box-selection with the left mouse button.

The four unwanted Hot Points are deleted.

To demonstrate the use of another algorithm, activate the SHELL MESH> MAP [Visible] function to mesh all

the visible unmeshed Macros with the Map algorithm.

JOIN

DELETE

Visible

MAP



Press ALL from the FOCUS commands to bring all the Macros

back.

Press the F9 key to zoom to all in the current view.

In the next area there is one skewed element. This could be corrected by increasing the nodal number of the nearby Perimeter Segment.

Activate the PERIMETERs> NUMBER function and select the

Segment with the left mouse button.

The Segment is highlighted and the Input window appears, displaying the current nodal number.

Input a value of 2 and press enter.

The Segment is now colored in red, indicating that its nodal number has been specified explicitly.

ALL

NUMBER

F9



Activate the SHELL MESH> RE-MESH [Visible] function to remesh the two visible unmeshed Macros.

Note that by now the number of OFF elements has dropped to only six. These will be corrected with the use of some manual functions for demonstration of that kind of functions.

Move to the next region shown. The problematic element will be corrected by a minor nodal movement.

Activate the GRIDs>MV SURF [SINGLE] function to move a selected Macro Area node. Select with the left

mouse button the node to be moved. Start moving the node. The motion takes place on the underlying CAD surface.

During the motion the participating elements are highlighted and their quality is continuously monitored and colored accordingly. In this case, as soon as the green color disappears the element is fixed. Press again the left mouse button to lock the node at its new position.

Move to the next region shown, with the two skewed elements.

Activate again the GRIDs>MV SURF [SINGLE] function to move a selected Perimeter node. Select with the left

mouse button the node to be moved. Start sliding the node along the Perimeter to improve its skewness.

SINGLE

MV SURF

Visible

RE-MESH

SINGLE

MV SURF



As soon as the element seizes to be green press the left mouse button again to lock the node at its new position.

Note that although this move improved the quality of the element concerned, it deteriorated the neighboring element.

Still in the same function select with the left mouse button the Perimeter node shown to improve the element. Move the node and press left mouse button again to lock it.

Still in the MV.SURF function select with the left mouse button the node of the remaining skewed element and begin sliding it along the Perimeter.

To lock the node to its new position, press the left mouse button again.

Move finally to the last problematic area.

Although you could improve the skewness of the elements by moving the nodes with the MV.SURF function, a much better result can be achieved in the following way.



Activate the ELEMENTs> SPLIT [Shells] function. The Selection Mode window appears. Keep only the Edges

flag active, so that you select element edges only. Select the three edges shown with the left mouse button.

(De-select with the right mouse button if necessary).


The Split Options window appears. Press OK.

Note that the split operation left two QUAD elements that should be removed, so that the volume can be meshed with tetra elements later.

Activate the GRIDs>PASTE function. Ignore the Paste window

that appears, as it is required for more advanced use.

Select with the left mouse button the nodes with the same order as shown.

Confirm with middle mouse button.

The first node was pasted onto the other and as a result the QUAD elements was collapsed to a TRIA, and the collapsed small TRIA has been completely removed.

Perform the same operation for the other element.

(Note that you can paste more than one nodes to another. All the selected nodes are pasted to the last selected one. Hence you could perform the above two-step operation in a single one.)

1

2

1

2

PASTE

Shells

SPLIT



The resulting mesh quality is improved.

There are no more skewed elements. Save the file from FILE>SAVE.

Notes

You should always aim to produce a good quality mesh by shaping properly the Macro Areas, using the most suitable meshing algorithm and adjusting the Perimeter element length or number. This is the faster way and it also assures that if the mesh is erased for some reason, a simple remesh operation will bring it back exactly as it was. On the contrary, corrections that were made using manual nodal movements and element splitting are not retrieved during remeshing. The powerful Reconstruction algorithm, available from ANSA version 11.3.0, can be used during or after the mesh generation to correct most of the problems that were resolved manually in this section, thus saving time in model creation. See the ANSA Users Guide section 9.4.4. for details on the use of Reconstruction.

without Reconstruction with Reconstruction



3.6. Remesh the volume

Having completed the surface mesh, mesh the Volume entity again. Remember that you do not have to define the Volume entity, as it exists from your work in Section 3.3.

Activate the VOLUMEs> MESHV [TET MESH] function and select the Volume with the left

mouse button. Confirm with middle mouse button.

As the Macros Areas are meshed their mesh will be used as a starting mesh for the tetra elements.

The volume mesh generation process

begins. A progress bar appears as well as messages in the Text Window.

15295 tetra elements in the volume, as reported in the text legend on the bottom left of the display.

While still in HIDDEN display mode to examine the mesh

quality, no OFF elements are reported

De-activate the MACROs visibility flag to remove the Macro

Areas from the view. Only the tetra volume elements remain visible.

Switch to SHADOW display mode to better view the volume

mesh.

Save the file form FILE>SAVE.

SHADOW

TET MESH

MESHV

HIDDEN

MACROs



3.7. Obtain information about the mesh.

ANSA can provide various type of information in a report format

through the D.INFO (Deck Info) command in the DECK menu (for all DECKS).

Activate the D.INFO function, located at the bottom of the

DECK menu. The Deck info parameters window appears. Select the type of information you want to acquire by activating the respective flag button. Activate the Solid and Shell info flags. Activate the Skewness flag in the SHELL QUALITY section, to obtain information about the skewness quality of the surface mesh. Activate also the Skewness flag button in the SOLID QUALITY section, to obtain information about the skewness of the volume mesh. Click on the Custom button. The Threshold Values window appears.

In this window there are five subdivisions of the whole range of values that this criterion takes. Having selected the IDEAS solid skewness definition, the default subdivisions have to be altered, as the specific criterion ranges from zero to one. Type in the value 1 in the last entry box and press on the Distribute button. The limits of the subdivisions are automatically redistributed. Press OK to close.

Back to the Deck info parameters window, activate the WHOLE DB (Whole Database) flag so that you get information for all the entities in the Database and not only for the visible ones. Remember that at the moment only the solid elements are visible, as the MACROs visibility flag is de-activated. Press OK in the Deck info parameters window to obtain the information. The Deck Report-Information window opens, displaying all the information.

D.INFO

DECK >



Scroll down the window to find: Min & Max ID and number and type of shell elements. Min, Max and Average element length of shell elements. Min & Max ID and number and type of solid elements. Scroll down in the window to view the rest of the information.

Shell skewness info ID of best and worst element with respect to skewness. Distribution of shell skewness (absolute and percentage) ID of tria shell with worst skewness (note down this ID, see next page)

ID of best and worst element with respect to skewness. Distribution of solid skewness (absolute and percentage) Press the SAVE AS button to save the info to a text file or press ESC to exit.



Based on the above information, you can locate elements of best or worst quality in your model.

Activate the visibility of Macros and de-activate SHADOW display mode.

Activate the ELEMENTs>INFO [PICK] function. The Input window appears. Type-in the ID of the element you want to

locate. In this case the ID of the worst skewness element is entered, ID=4149 (note that this ID will not be the same in your case as it depends on the order that the elements were generated during meshing, so make sure you type the ID of the element reported by Deck Info).

Make sure the FE-Mod. flag is active.

Press enter to locate the element. ANSA automatically highlights and zooms to the specific element. While still in the function you can manipulate the view to identify the nearby region and press enter again to zoom to the element.

(From ANSA v11.3.1 the EXTREME function can zoom automatically to worst element).

(Note if you are in HIDDEN display mode you may not be able to see the element if it is hidden behind).

Activate the Presentation Parameters window by pressing the F11 key. Activate the Elements flag at the bottom of the window and press OK to

exit.

Now the IDs of the elements appear on the screen. (Note that some Macros have been removed for clarity).

To obtain more information about the specific element activate the ELEMENTs>INFO [INFO] function and select the element

from its center with the left mouse button. The element card opens and information is provided in the Text Window.

PICK

INFO

MACROs

SHADOW

F11

INFO

INFO

FE-Mod.



3.8. Obtain information about the component

The D.INFO function can also be used to inquire about the volume, the mass and the center of gravity (CoG) of a meshed solid part.

Prior to this however you must specify the correct material properties.

Activate the Material List from the M.LIST button. The Materials

window appears. Select the single Material 1 from the list and press EDIT. (Note that the appearance of the cards depends on the active DECK, which in this case is NASTRAN).

The MAT1 card opens. Note that length units are mm and mass units are kg.

Change the name to "steel" in the top field and then type in 210 (kN/mm

2) for the Youngs

Modulus and 7.85x10-6

(kg/mm3) for the density.

Press OK to confirm and close the card.

Back in the Materials window the name has been updated. Press ESC to exit from the Materials window.

De-activate MACROs visibility, and leave only the Volume entity

visible.

Stay in WIRE display mode.

Activate the D.INFO function. The Deck info parameters window

appears. De-activate all previous flag button selections. Activate the Mass info flag. Activate the Visible flag so that now you obtain this type of information about the visible entities, in this case the solid tetra elements. Press OK to get the information report.

M.LIST

WIRE

D.INFO

MACROs



In the Deck Report-Information window that opens you will find:

Total mass of solids (1.458 kg).

Coordinates of CoG.

Inertia tensor.

Principal Inertias

&

Directions

Total volume of component (1.86x105 mm

3).

The CoG position and principal axes are also presented graphically on the screen. (Move the Deck-Report-Information window aside to view the part. Do not exit from the window, as the axes will disappear). Note that the units of the output correspond to the units that you use for the specification of length and material properties.

Press the SAVE AS button to save the info to a text file, or press ESC to exit. The tetra volume meshing task has been completed. Save the file from FILE>SAVE. Quit ANSA from FILE>QUIT.



3.9. Prepare the geometry for Hexa meshing

Start ANSA, read in the file solid.ansa that

you have saved in Section 3.1., and save it as solid_hexa.ansa from FILE>SAVE AS.

To create a Hexa mesh you must decompose the solid part into sub-volume blocks that can be meshed by the Volume MAP algorithm. To do so you will use certain CAD functions of ANSA to cut Faces at specific convenient locations, and also create new Faces that will be the interior boundaries of connected sub-volumes.

The volume decomposition must be made always with the scope that:

- The Volume MAP algorithm requires two opposite sets of Macros (master and slave), with compatible shell mesh, and that all the bounding guiding sets of Macros, which close the volume and define the extrusion direction, are meshed with quad mapped mesh only. Careful Perimeter nodal alignment will be required to satisfy this requirement.

- To achieve solid mesh continuity, the created interior Faces, and hence Macros, must belong to both adjacent Volumes.

- The blocks must have ideally orthogonal corners, so that the generated hexas are of good quality.

The image below describes the volume decomposition that will be performed in order to generate the hexa mesh. Five sub-volumes will be created and meshed separately. The extrusion directions are displayed by an arrow, indicating which surfaces will be master and slave sets and which will be guiding sets.

volume5

volume4

volume2

volume3

volume1



Begin with the creation of volume1. You must cut Faces to separate the sub-volume from the main body. View the part exactly as shown here.

Activate the FACEs>PRJ-CUT (Project-Cut) function and select

with the left mouse button the Hot Point shown (1). Then select with the left mouse button the CONS shown (2). Pay attention to select these Hot Points, and not other ones.

The Hot Point is projected to the CONS and a CUT is made between the two positions. As you are still in the function the last Hot Point remains selected for projection. Select with the left mouse button the other CONS (3).

The last Hot Point is projected and another Cut is made in that Face. The new Hot Point remains selected. Press the ESC key to exit from the function.

Activate the FACEs>CUT function and cut the Faces between the

two Hot Points as shown.

PRJ-CUT

CUT

1

2

1

2

3



Now all four sides are cut at that location. In order to facilitate visualization and manipulation of sub-volumes you can create new PIDs and assign them to selected Faces. You can also have correspondence of PID and volume ID. To do so, first change the ID of the default existing PID in the database from 1 to 100.

Open the Properties window from the PR.LIST button.

Select the Property in the list and press EDIT. The Shell Property window appears. Change the PID from 1 to 100 and press OK.

This is to free up the PID numbers 1 to 5 so that they are assigned to the Faces that define the sub-volumes 1 to 5 that will be created, for correspondence purposes.

Activate the FACEs>SET PID function and select with the left

mouse button the Faces that form volume1. The selected Faces become highlighted. De-select with the right mouse button if necessary. Close selection with the middle mouse button. The Properties window appears. Press NEW to create a new PID with ID=1 and name

"shells of volume1". A new Shell Property window opens. Type in the name and ID as shown.

To specify the PID color press the ColorEdit button.

PR.LST

SET PID



The Material Editor window appears. Type the letter y (for yellow) in the Filter field. Select one of the available yellow colors. Press OK to confirm and exit. Returning to the Shell Property window press again OK to close.

Back in the main Properties window, the newly created PID is highlighted in black. Double click on it to select it. The selected Faces now belong to this PID.

To view this, switch to PID and SHADOW display mode.

To proceed with the remaining part remove from the display PID 1 by performing a NOT operation in PID mode.

Return to ENT display mode.

Press LOCK in the FOCUS Group of commands to lock the

currently visible entities.

Note in the following steps the SHADOW mode is active for clarity. You can however proceed without it, if you prefer so.

ENT ..

LOCK



You will now treat the fillet region. This fillet must be split in half and shared between volumes 2 and 3.

This will be performed using the FACEs>DACH [DIVIDE FACE] function. Before doing so, you must isolate one edge of the fillet so that you

can select it. Perform a NOT operation in ENT mode as shown.

Activate the FACEs>DACH [DIVIDE FACE] function and select with the left

mouse button the edge of the fillet as shown.

ANSA identifies the whole string of Faces forming the fillet and highlights them. It also provides a preview of the fillet splitting. The Divide Parameters window opens. Activate the Join Macros flag and press OK to proceed.

Press ALL from the FOCUS Group to bring back all the

entities that were visible when the LOCK flag was activated.

The fillet was split in two and the initial boundaries of the fillet were joined to form wider Macro Areas in the MESH menu, and are therefore colored in a brown color.

DIVIDE FACE

DACH

ALL



Rotate the part to the other side. You will cut the two Faces at the locations shown.

Activate the FACEs>CUT function and select with the left mouse

button the Hot Points shown.

Perform NOT operations to remove all Faces except those

forming part of volume3. You should leave visible only the Faces shown below.


mouse button the Faces that form part of volume3. Close selection with the middle mouse button. Press NEW in the Properties window that appears and create a new PID with ID=3 and

name "shells of volume3". From ColorEdit select a red color for this PID. Double click on the highlighted new PID to select it. The selected Faces now have a PID=3.

Press ALL to bring all the locked entities back.

Switch to PID display mode.


Note that these were not all the Faces that form volume3. In a later step, it will be easier to add the remaining Faces to this PID.

CUT

NOT

SET PID

ALL

PID ..

1

2

1

2




De-activate the LOCK flag in the FOCUS Group to clear the old

selection.

Press again the LOCK flag to lock the new current entities.

Now you will form volume4.

Perform an OR operation in ENT mode to isolate the Faces of

interest.

The aim now is to cut the Face (shown in gray color here) not by a simple straight line between the two Hot Points using the CUT function, but along a curved line, similar to that of the CONS of the opposite Face.

(Note that you cannot achieve the desired result with the CONS>PROJECT function as the CONS does not have the exact length for the cut).

To achieve this you will use the help of the 3D Curves.

Activate the CURVEs visibility flag.

Activate the CURVEs>TRANSF. function and select with the left

mouse button the CONS shown. De-select with the right mouse button if required.

LOCK

ENT ..

LOCK

OR

CURVEs

TRANSF.




An arrow appears indicating the start of the selected segment.

Now pick with the left mouse button two positions corresponding to the start and end of the selected segment, according to the direction of the preview arrow.

A new 3D Curve is created by a transformation between initial and target start and end positions from the original segment.

You will now cut the Face using this new 3D Curve.

Activate the CONS>PROJECT [NORMAL] function and select with the left mouse

button the 3D Curve.

Confirm with the middle mouse button.

1

2

NORMAL

PROJECT



Now select the Face on which the 3D Curve will be projected.

Confirm with middle mouse button

The Face is now cut in the desired shape.

Perform a NOT operation in ENT mode to remove the lower part of

the Face from the view.

Now you must separate the small bit at the front. This will be performed by simple Project-Cut operations.

Activate the FACEs>PRJ-CUT function and select the Hot Point

(1) and then the CONS (2) on which the projection will take place.

PRJ-CUT

1

2

NOT



The Hot Point is projected and a Cut is made between the two positions.

Note that the new Hot Point remains selected.

Press middle mouse button to be able to select a different Hot Point without exiting from the function.

Rotate to the other side, and select the other Hot Point (1) and then the opposite CONS (2).

Similarly a new cut is made.

Press ESC to exit the function.

Perform NOT operations in ENT mode to remove the small Faces

that do not belong to volume4.

NOT

1

2




mouse button the Faces that form volume4. Close selection with the middle mouse button. Press NEW in the Properties window that appears and create a new PID with ID=4 and

name "shells of volume4". From ColorEdit select a magenta color for this PID. Double click on the highlighted new PID to select it. The selected Faces now have a PID=4.





selection.


Performing the appropriate NOT operations in ENT mode, leave

the four Faces shown that form volume5.

SET PID

LOCK

ENT ..

LOCK

NOT




mouse button the Faces that form volume5. Close selection with the middle mouse button. Press NEW in the Properties window that appears and create a new PID with ID=5 and

name "shells of volume5". From ColorEdit select a blue color for this PID.

Double click on the highlighted new PID to select it. The selected Faces now have a PID=5.

Press ALL to bring all locked entities.

Switch to PID and SHADOW display mode to check that the correct PID has been assigned.

To proceed with the remaining part perform an OR operation in PID mode.



selection.


The remaining part must be split in two, half of it will be merged to PID3 and the other will form volume2 with PID=2.


(1) and then the CONS (2) on which the projection will take place.

SET PID

LOCK

ENT ..

LOCK

PRJ-CUT

1

2

ALL



The Face is cut and the new Hot Point remains selected.


Activate the FACEs>CUT function and cut the Face between the two

selected Hot Points.

The Face is split.

Move to the opposite side, and cut between the two selected Hot Points.

Still in the same function select the Hot Points.

The Face is split.

CUT

CUT



Viewing the part from below, you will now cut the upper side along a curve similar to the shape of this bottom curve.

To prepare the lower CONS project the Hot Point from the upper side on it, so that it has the appropriate length.

Activate the HOT POINTs> PROJECT function and select the

Hot Point (1) and then the CONS (2).

A new Hot Point is created at the projection of the selected one.

Activate the CURVEs>TRANSF. function and select with the left

mouse button the two CONS shown.


An arrow appears indicating the start of the selected segment of CONS.

PROJECT

TRANSF.

1

2



Rotate to the upper side.

Now pick with the left mouse button two positions corresponding to the start and end of the selected segment, according to the direction of the preview arrow.

Two new 3D Curves are created by a transformation from the original segment.

Now you will cut the Faces using these two 3D Curves.

Activate the CONS> PROJECT [NORMAL] function and select with the left mouse button the two 3D

Curves.

Confirm selections with middle mouse button.

Select the two Faces on which the 3D Curves will be projected. Select the Faces from their common CONS. De-select with right mouse button if necessary.


1

2

NORMAL

PROJECT



The two Faces are cut in a similar shape as that of the bottom side.

De-activate 3D Curves visibility flag, as you no longer need

them.

Perform appropriate NOT operations in ENT mode to keep

only the Faces that will be merged to PID3 as they also belong to volume3.


mouse button the Faces. Close selection with the middle mouse button. In this case double click on the existing PID3 in the Properties window to select it.

The selected Faces acquire PID=3. To view this, switch to PID and SHADOW display mode.

To proceed with the remaining part perform an OR operation in

PID mode.

NOT

SET PID

CURVEs

OR



The Faces that now remain visible form volume2.


mouse button the Faces. Close selection with the middle mouse button.

Press NEW in the Properties window that appears and create a new PID with ID=2 and

name "shells of volume2". From ColorEdit select an aqua color for this PID. Double click on the highlighted new PID to select it. The selected Faces now have a PID=2.


De-activate the LOCK flag in the FOCUS.

Press ALL to bring all the Faces back and view the whole

component with its sub-volumes.

The task is completed.

Save the file from FILE>SAVE.

SET PID

ALL

LOCK



3.10. Create the interior Faces of the sub-volumes

To mesh each sub-volume you must create interior Faces in order to close them. Begin with volume1.

Perform an OR operation in PID mode to isolate it.

Activate the SURFs>COONS function and select sequentially

the four CONS that form the Face to be created in order to close the volume. De-select with right mouse button if necessary. (Ignore the COONS Options window that appears).

Confirm selection with middle mouse button.

A wire frame preview of the Surface to be generated is given and the Accept Surface window appears. Press OK to proceed with the creation of the Face.

The Face is created and the sub-volume is now closed. As this Face will be the common boundary of the two adjacent sub-volumes, it is helpful to put it in a different PID. You can use PID 100 which is unused for all the interior Faces that you will create.

Activate crosshatch visibility flag button so that you can select

Faces from their crosshatch.

OR

COONS

CROSH

1

2

3

4




mouse button the new Face from its crosshatch. Close selection with the middle mouse button.

The Properties window opens. Double click on PID=100 to place the Face in this unused PID.

The Face is now colored in gray, the color of PID 100.

Press the INVERT function of the FOCUS Group. Visibility of

entities in inverted.

Perform an OR operation in PID, to isolate volume3.

Rotate the sub-volume to view its opening.


the CONS that form the Face to be created in order to close the volume. Begin selection from a CONS that belongs to a corner of the Face to be created. Zoom closer so that you do not miss any small CONS.

De-select with right mouse button if necessary. Confirm with middle mouse button.

SET PID

INVERT

OR

COONS1

2

3




Note that ANSA created two Faces instead of one, so that the underlying Surfaces are of better quality.


mouse button the new Faces from their crosshatch. Close selection with the middle mouse button.

The Properties window opens. Double click on PID=100 to place the Face in this PID.

The Faces are now colored in gray, the color of PID 100.

SET PID



Press the INVERT function of the FOCUS Group. Visibility of

entities in inverted.

Perform an OR operation in PID, to isolate volume4.

Rotate the sub-volume to view its opening.


the three CONS shown. Confirm with middle mouse button.

A wire frame preview of the Surface to be generated is given and the Accept Surface window appears. Note that in this case, as you have not specified all the boundaries of the Face to be created you have two options. The first one shown here closes the Surface with a straight line.

Press Alt. to preview the second option.

The second option closes the Surfaces with a curve that has the same curvature as that of the opposite boundary. Press OK to accept this Surface.

INVERT

OR

COONS

1

2

3



The Face is created. Now there is this small opening that must be closed.


the four CONS shown. Confirm with middle mouse button.


The Face is created and the gap is closed. Now you can assign the two new Faces to PID=100.

COONS

1

2 3

4




mouse button the new Faces from their crosshatch. Close selection with the middle mouse button.

The Properties window opens. Double click on PID=100 to place the Face in this PID.

The Faces are now colored in gray, the color of PID 100.

Press ALL to bring all the Faces back.

Perform NOT operations in PID mode so that you are left with

volume5 and the Faces of PID=100.

You should view the Faces shown.

Perform NOT operations in ENT mode as shown to isolate the

Faces of volume5. Keep also the interior Face of PID=100 that you created earlier, as it also belongs to this volume too.

SET PID

ALL

NOT

NOT



Rotate the view so that the small opening becomes visible.


the four CONS shown. Confirm with middle mouse button.

Press OK to accept the previewed Surface

The Properties window opens. Double click on PID=100 to place the Face in this PID. Volume5 is now closed.


Switch to ENT display mode, de-activate SHADOW and Crosshatch visibility flags.

There should not be any red CONS visible which would indicate lack of connectivity of the Faces. Cyan CONS are visible at boundaries of the created interior Faces.


COONS

ALL

1

2 3

4



3.11. Generate the Quad Surface mesh

Switch to the MESH menu to begin the surface mesh. The task

now is to produce a purely quad map mesh on all the Macro Areas. This will require that you shape the Macros in such a way that map mesh is possible. To achieve this you will join specific Perimeter Segments and cut new ones.

You will switch to the TOPO menu occasionally, for some special cuts.

Using appropriate OR and NOT operations in ENT and PID modes isolate the Macros of volume1. Include also the interior Macro that belongs to PID100 in order to have the complete closed sub-volume description.

Activate the LOCK flag from the FOCUS group to lock the current

visible entities. You will focus initially on the region near the hole which is more complicated for a map mesh.

First define the locations where you will cut the Macros to separate the region around the hole.

Activate the HOT POINTs> PARAM. function, and select with

the left mouse button the Perimeter Segment shown. Select it by picking near the left end so that it is recognized as start of segment.

An arrow appears indicating the direction from start to end of the Segment. The Input window opens. Type in the ~ symbol and the value 11, in order to insert a Hot Point at an absolute distance of 11 mm along the selected Perimeter Segment.

Press enter to proceed.

PARAM.

LOCK

MESH >

Macro with PID 100



The Hot Point is inserted as shown.

Still in the function select with the right mouse button the other Segment, to re-apply the last command.

Another Hot Point is inserted at a distance of 11 mm along that Segment.

Now select with the left mouse button the Segment shown so that you insert a Hot point at a different distance than the previous.

An arrow appears to indicate the start to end direction, and the Input window opens. This time specify an absolute distance of 12 mm. (The distance here is larger to follow the conical shape of the hole).

Press enter to proceed.

A Hot Point is inserted at a distance of 12 mm along the Segment.

Still in the function select with the right mouse button the other Segment, to re-apply the last command.



Another Hot Point is inserted at a distance of 12 mm along the Segment.

(Note that you could have inserted the Hot Points using the simple HOT POINTs>INSERT and PROJECT commands at appropriate locations. However to ensure that you accurately reproduce the example here, the Hot Points were inserted at the exact locations as specified with the help of the PARAM. function).

Activate the MACROs>CUT [Cut] function and select with the left mouse button the Hot Points shown, in order to cut

the Macro Area in two.

Still in the function select Hot Points in pairs to cut the other three Macros as shown.

Switch to TOPO menu to create zone cuts around the holes, so

that you can mesh a row of quad elements around them.

Switch to SHADOW mode and activate the visibility of CROSSHATCHES to facilitate selections.

TOPO >

CROSH

SHADOW

Cut

CUT



Activate the FACEs>ZONECUT function. Select sequentially the

four CONS of the hole.

De-select with right mouse button if required and confirm with middle mouse button.

Next select with the left mouse button from its crosshatch, the Face on which the zonecut will be made.


The Input window appears.

Type in the offset distance for the zonecut and press enter.

The selected CONS have been offset and a cut has been made at the specified distance.

Turn to the other side of the hole and perform the same to make a similar zonecut at 3mm.

1

2

3

4

ZONECUT



Having created the zones you will cut the Faces along the line shown. The Project Cut function will be used for this.


at the top (1).

Next select the CONS (2) on which the projection will be made.

The Hot Point is projected and the cut is made.

The new Hot Point remains selected so proceed with the selection of the next CONS (3) to continue the cut.


Turn to the other side of the hole and perform the same.

De-activate SHADOW mode.

PRJ-CUT

1

2

3



Switch back to MESH menu. The part should appear as shown.

Activate the MACROs>JOIN function and select with the left

mouse button the Segments shown, four of them inside the hole and two on the outside.

(Rotate the part and zoom in accordingly to make a clear selection. You can retrieve an unintentionally joined Segment using the MACROs>RELEASE function. You cannot however retrieve cuts that you made, you must recreate them from the start)

Activate the HOT POINTs> DELETE function and select with

box selection the unused Hot Points. Select individually Hot Points that were not removed by box selection.

You should leave the part as shown. If some Hot Points were not deleted by the box selection, delete them by picking them with the left mouse button.

Switch to the TOPO menu to make a cut inside the hole (Note

that in TOPO the cut operation is not view dependant, as it is in the MESH menu, and so in this case it is more appropriate to make a straight line cut).

Activate the FACEs>CUT function and make a cut inside the hole

between the two Hot Points shown.

JOIN

DELETE

CUT

MESH >

TOPO >



Switch back to the MESH menu.

Activate the PERIMETERs> NUMBER function and select the

Perimeter Segment shown. The Input window appears. Type the value 12 and press enter.

Twelve Perimeter nodes were assigned to the Segment which is now colored in red.

Still in the same function select with the right mouse button the other Segment to apply the same nodal number to it, too.

Similarly for the two Segments at the bottom.

Still in the NUMBER function select with the left mouse button the Segment shown and assign 6 Perimeter nodes to it.

NUMBER

MESH >

12

12

12

6



Use the right mouse button to assign the same number to the Segments shown.

In a similar manner assign also 1 node on the Segment shown.

Activate the MACROs>CUT [Cut] function and perform the four cuts shown. Be careful to select exactly the Perimeter

Nodes that are shown to perform the cuts.

Activate the MACROs>CUT [Prj-Cut] function (Project-Cut) and select the Perimeter Node shown and then the

Perimeter Segment.

1

2

6

6

6

6

6

1

Cut

CUT

Prj-Cut

CUT



With the new Hot Point selected pick on the other Perimeter Segment to continue the cut.

The cut is made. The last Hot Point remains selected.

Press middle mouse button to be able to select a different Hot Point to make the same cut on the other side.

Select with the left mouse button the Perimeter Node shown.

Select the two Perimeter Segments to make the cut as before.


3



Activate the MACROs>CUT [Cut] function and make the two cuts shown between the selected Hot Points and

Perimeter Nodes shown.

Activate the PERIMETERs> NUMBER function and assign

one node on these Segments.

Still in the number function select the Segment shown with the left mouse button. As the Input window appears displaying the current nodal number of 4, select with the cursor (which now has a ? symbol) another Segment to copy its number to the window.

Press enter to apply the new nodal number.

Use the right mouse button to assign the same number on the other three Segments.

NUMBER

?

1

1

2

2

2

Cut

CUT



Assign 6 nodes to the two remaining vertical Segments.

The Macros are now ready to be meshed with the Map algorithm.

Activate the SHELL MESH> MAP [Select] function and select with left mouse button the Macro Areas to be

meshed. De-select with right mouse button if necessary.

Press middle mouse button to confirm selection.

All selected Macros are meshed as reported in the Text Window.

(In the case where some Macros were not meshed, this is due to improper nodal number of some Perimeters, and as a result the map algorithm cannot be applied. Identify these Segments and assign them correct nodal number).

Activate SHADOW display mode to view the mesh better. Note

that in the legend only quad elements are reported. No triangles should be listed there, which would indicate improper nodal number and the generation of tria elements.

Select

MAP

SHADOW

6

6



To view the mesh even clearer, activate the GRAPHICS function

from the main pull down menu. The Benchmark Settings window appears. De-activate the

SHADOW UNMESH flag

at the bottom of the window and press OK.

Now only the meshed Macros appear shaded, and can be easily distinguished from the unmeshed ones.

Use MACROs>JOIN to join this Segment and delete the leftover

Hot Point with HOT POINTs>DELETE.

Note that this Segment is not joined as it is an important feature line that must be retained even if it stretches the resulting map mesh that will be generated.

To minimize this stretching you can place two Hot Points on the opposite side so as to spread it on the side Macros, too.

Activate the HOT POINTs> PARAM. function and insert a Hot

Point on the Segments at the locations shown.

Activate the MACROs>CUT [Cut] function and cut the Macros between the Hot Point locations.

Now you must assign proper nodal numbers to the Perimeter Segments to mesh them with the Map algorithm.

GRAPHICS

JOIN

PARAM.

38

19

Cut

CUT



Activate the PERIMETERs> NUMBER function and assign the

nodal numbers shown.

Activate the SHELL MESH> MAP [Visible] function to mesh all the visible unmeshed Macro Areas with the Map

algorithm.

All the Macros are meshed as reported in the Text window. The surface mesh of volume1 is complete.

Save the file from FILE>SAVE. De-activate the LOCK flag.

Press ALL to bring all the entities back in view.

You will proceed with the mesh of volume4 which has similar characteristics.

Switch to TOPO menu and isolate the Faces that form volume4.

Include also the interior Faces that belong to PID=100.

Activate the LOCK flag button.

6

6

6

5

6

6

6

6

5

5

6

5

6

6

NUMBER

Visible

MAP

ALL

LOCK

LOCK

6

TOPO >



Activate the FACEs>ZONECUT. Select sequentially the four

CONS of the hole. De-select with right mouse button if required and confirm with middle mouse button.

Select with the left mouse button the Face shown from its crosshatch. Confirm with middle mouse button. The Input window appears.

Type in an offset distance of 3mm and press enter.

A zonecut is made at the specified distance.

Switch to MESH menu.

Activate the MACROs>JOIN function and select the Perimeter

Segment inside the hole so that they are removed.

JOIN

ZONECUT



The part should look like this.

Activate the HOT POINTs> DELETE function and delete the

unused Hot Points.

Perform an OR operation to keep only one side of the part.

View the Macros head on.

Assign 8 nodes using the PERIMETERs>NUMBER function

to the Segment shown.

Project the Perimeter Nodes shown to create Hot Points on the

two circular Segments using the HOT POINTs>PROJECT function.

Delete the two original Hot Points.

DELETE

OR

NUMBER

PROJECT

DELETE

8



Assign 13 nodes to the two circular Segments.

Cut the Macro at the six locations shown using the MACROs>CUT [Cut] function.

Assign one node to the three Segments as shown.

Assign two nodes for two Segments.


algorithm.

NUMBER

NUMBER

NUMBER

Visible

MAP

13

13

1 1

1

2 2

Cut

CUT



Press ALL to bring all locked entities back.

Activate SHADOW mode.

Rotate the part.

Activate the MACROs>RELEASE function. A preview of all joined

Perimeter Segment is given in light brown color. Select with the left mouse button the string of two Segments inside the top of the hole.

The two selected Perimeter Segments are released.

Delete the two unused Hot Points.

Project the two Hot Points from the meshed side of the hole to the

unmeshed one.

RELEASE

DELETE

PROJECT

ALL

SHADOW



The part should look like this.

Assign 6 nodes to the two Perimeters shown.

Assign the nodal numbers shown to the remaining Perimeters.


algorithm. All Macros are meshed except one as reported in the Text Window. This Macro was not shaped properly for Map quad mesh on purpose, so that it can be demonstrated later that it can be meshed automatically during Volume meshing.

3

8 3 4

4

4

4 4

4

2

2

NUMBER

NUMBER

Visible

MAP

6

6



De-activate the LOCK flag.

Performing appropriate OR and NOT operations leave only the Faces of volume5 visible.

Assign 8 nodes to the Perimeter shown.

Activate the SHELL MESH> MAP [Visible] function to mesh all the visible unmeshed Macro Areas with

the Map algorithm. All Macros are meshed with quad elements.


Visible

MAP

NUMBER

ALL

LOCK

8



Perform appropriate OR and NOT operations to leave only volumes 2 and 3 visible.

For display purposes, the SHADOW UNMESH flag is here

activated again in the Benchmark Settings window under the GRAPHICS function.

It may however be better to leave it inactive so that selection of Segments is clearer.

Zoom at the top as shown and join the Segments shown. Pay

attention not to select other Segments by mistake.

The Segments are removed.

GRAPHICS

JOIN



Turn to the bottom side and join the other Segments.

Delete all unused Hot Points from both sides.

Note that this Hot Point cannot be deleted as there is a Perimeter Segment connected there. This would be visible if the SHADOW UNMESHED flag was inactive.

Perform a NOT operation in PID form to remove the Macros of volume3. View volume2 from the top as shown. Now you must perform some cuts that will result in near square Macro Areas suitable for map mesh.

DELETE



Make a Cut between the Perimeter Nodes shown.

(Note the yellow numbers indicate the perimeter nodes, to help you identify from which perimeter node you should make the cut.)

Make another cut as shown.

Assign 8 nodes to the Segment shown.

Activate the MACROs>CUT [Prj-Cut] function and perform the two cuts shown starting from the red Segment.

3

3

3

3

4

NUMBER

8

Cut

CUT

Prj-Cut

CUT



De-activate SHADOW display mode.

Project the three Hot Points to the bottom Segments as shown, and

two more to the opposite one.

Perform the four corresponding cuts shown at the bottom side.

Assign the nodal numbers shown to the Perimeter Segments.

Proceed with the other Segments.

2

2

5

5

5

5

5

2

2

2

5

2 2

PROJECT

NUMBER

NUMBER

Cut

CUT



Perform the three vertical cuts shown.

Assign 6 nodes to all vertical Segments.

Assign the nodal numbers shown.

View from bottom. Again SHADOW mode is activated here for clarity. You can continue with WIRE so that selections are easier.

6

6

6

6

6

6

6

NUMBER

NUMBER

3 4

4

3

4

3

5

5

5

Cut

CUT



Perform the two cuts shown.


Check that all Perimeters have aligned nodal numbers for mapped mesh.



NUMBER

8

5

8

5

5

2

Visible

MAP

Cut

CUT



Press ALL to bring all Macros back.

Isolate the Macros of volume3. You will project this Hot Point to all the Perimeters below.

Activate the HOT POINTs> MULT.PR function and select the

Hot Point with the left mouse button. Confirm with middle mouse button.

Select with the left mouse button the Perimeter Segment and confirm with middle mouse button. A new Hot point is created at the projection location. Still in the function proceed with selecting the next Segment and confirming with middle mouse button.

Assign 12 nodes to these Segments so that they are

aligned with the nodes of the already meshed Macro of PID 100.

ALL

MULT.PR

NUMBER

12

12 12

12

12



Assign 9 nodes to these Segments and 8 to the top one.


Finally assign 6 nodes to all vertical Segments.

Check that all Perimeters have aligned nodal numbers for mapped mesh. The Macros are ready for map mesh.



NUMBER

3

3 3

3

3

4 4

3

6

6 6

6 6 6

6

6

Visible

MAP

9

9 9

9

NUMBER

NUMBER

8



Bring all Macros back.

The legend on the left should show 2502 quad elements. There should not be any trias. If there are some, or the number of quads is not 2502 then this means that the nodal assignment was not performed as it should on some Perimeters. This will lead to problems in the hexa volume meshing.

Press the UNMESHED [MACROS] button of the FOCUS group to check if there are any unmeshed Macro Areas. There should only be one unmeshed Macro, left like that intentionally as described in page 2-67. If it is not a problem of other unmeshed Macros, examine the part to identify the Perimeters with the wrong nodal number and correct them. The surface mesh is complete. Save the file from FILE>SAVE.

ALL



3.12. Generate the Hexa Volume Mesh

Isolate the meshed Macros of volume1. Ensure that you also include the Macro with PID=100 that closes the sub-volume. You will use the Volume Map algorithm to generate the hexa mesh. You will select in three steps the master, then the slave and finally the guiding sets of Macros.

To facilitate selection of sets stay in SHADOW mode.

Activate the VOLUMEs>MAP function.

Activate the flag in the Feature Angle selection tool window that appears.

Left click on an element of the Master Set. All the Macros within the specified feature angle limit are selected automatically. You can de-select with right mouse button if required. Confirm selection with middle mouse button. The message Master area OK appears in the Text Window.

Proceed with the selection of the slave set. Perform a similar left mouse button selection as shown. Confirm selection of slave set with middle mouse button. The message Slave area OK appears in the Text Window.

MAP



Without exiting the MAP function and before proceeding with the

guiding set selection de-activate the SHADOW mode. Verify the correctness of the Master and Slave set selections.

Now perform a box selection as shown to select the guiding set of Macros. Note that the master and slave sets will not be included in the guiding set selection although inside your box selection. Confirm selection of guiding set with middle mouse button.

The message compatible master/slave areas appears in the Text Window and the generated hexa elements are previewed.

The Accept Elements window appears. Press OK to proceed with the hexa elements.

(The Smooth option is not important here, as the geometries are simple, see section 10.3.2.2. of the Users Guide).

The Properties window appears to assign a PID to the generated hexas. As no solid PID exists in the database, press the NEW button to create a new one.

A new Solid Property card appears. Type in the

name "solids" in the top field.

Press OK to close the card.

SHADOW



Back in the main Properties window the newly created PID is highlighted.

Double click on it to select it.

The Part Manager opens so that you assign the new Volume entity and its hexa elements to a Part. Press NEW>PART to create a new EMPTY Part.

Specify the name "volume" in the Part Edit window that opens and press OK. Left click on the EMPTY part thumbnail to assign the created entities to this new Part.

Activate SHADOW display mode to view the mesh.

Ensure that VOLUME visibility flag is active so that you can see

and select the volume mesh. Notice that you can see both yellow and gray shells and facets on the same surfaces.

De-activate MACROs visibility to view the solid mesh only.


SHADOW

VOLUME

MACROs



Proceed in a similar manner with the hexa meshing of volumes 2, 3 and 5. Each time a new Volume entity is created the Property list window will appear and the Part Manager will open so that you assign Property and Module IDs. Assign to all Volumes the same PID=6 and

Part "volume". ! Note the extrusion directions and corresponding master and slave sets as shown in page 2-26. You should reach the result shown.

Finally isolate the Macros of volume4.

Activate the VOLUMEs>MAP function and select for master set the meshed Macros shown and for slave set the single unmeshed Macro Area. Finally, select the guiding set.

Upon confirmation of the guiding set the message Incompatible mesh, the slave will be replaced by an image of the master appears in the Text Window. The unmeshed slave macros is meshed automatically by an image of the master set mesh and the hexas are generated and previewed. Assign them to the same PID and Part as all the previous.

master set

slave set



Activate SHADOW display mode to view the meshed Macro Area.

Press ALL to bring all Macros and Volumes back. There should be 2555 quad shells and 3669 hexas.

The volume meshing is completed. Save the file from FILE>SAVE.



3.13. Examine and improve the quality of the Volume Mesh

You will examine the quality of the hexa elements with respect to IDEAS warp. Press the F11 key to activate the Presentation Parameters window. Activate the warping flag and keep the default threshold value of 10 degrees.

Press OK to close the window.

Switch to HIDDEN display mode. 93 hexas are reported as warped

in the legend and are colored in light blue.

Press the EXTREME button to isolate the violating elements.

These elements will be corrected by the Improve Quality function. This function automatically moves the nodes of the violating elements so as to improve their quality. In this example you will use this function only for the hexa elements and not for the surface mesh.

Press ALL to bring everything back.

Activate the MACROs> FREEZE.function and select all

the Macro Areas with box selection. Confirm with middle mouse button.

The Macro Areas are now colored in blue (in ENT mode) indicating that they are frozen and that no action can be performed on them. So the Improve Quality function will not move any nodes of the surface mesh.

Activate the ELEMENTs>REDUCE [Improve Quality] function. The Improve

Quality window opens. Activate the Warping flag and press OK.

Press OK two or three times more until all hexas (apart from the four connected to the surface) are improved. The task is completed. Sav

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3 Solid Mesh