2021.11

1.1 Release Notes: Coreform Cubit 2020.2

1.1.1 Graphical User Interface
1.1.2 Meshing
1.1.3 Geometry
1.1.4 Sculpt
1.1.5 Graphics, Utilities, etc
1.1.6 Other fixes and enhancements
1.1.7 Graphical User Interface
1.1.7.1 New Geometry Power Tool Diagnostics and Solutions

/home/slaughter/trelis/help/Trelis_User_Help/contents/assets/images/new_in_2020_2/geom_power_tool1.png

Figure 1:

/home/slaughter/trelis/help/Trelis_User_Help/contents/assets/images/new_in_2020_2/geom_power_tool2.png

Figure 2:

The Geometry power tool includes interactive diagnostics and solutions for defeaturing and repairing CAD models. New diagnostic tests have been added along with rapid solutions for repair. Updated and expanded diagnostics categories include Traits and Assembly Checks.

1.1.7.1.1 New Command Panel Navigation Method

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Figure 3:

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Figure 4:

A new, optional, method for navigating the command panels has been added. This new option can be toggled on and off under Tools > Options > Command Panels. The obvious benefit of using this “breadcrumb” navigation method is gaining additional vertical space for command panels which will eliminate the need for scrolling in many cases.

1.1.7.1.2 Support for Dark Mode

Support for Dark Mode has been added to Cubit 2020.2.

1.1.7.1.3 Display Volume Overlaps and Neighbors from Context Menu

/home/slaughter/trelis/help/Trelis_User_Help/contents/assets/images/new_in_2020_2/overlaps.png

Figure 5:

Two new options are available in the graphics window when volumes are selected:

1.1.7.1.4 Tetmesh and Trimesh GUI Command Panels

A new command panel for setting options for the tetmesh scheme is now available supporting all new local and global options for tetrahedral meshing. This panel now includes two separate tabs for setting options for surface meshing and volume mesh options. The trimesh panel has also been updated in a similar manner for setting options for the trimesh scheme.

1.1.7.1.5 Reduce Bolts Command Panel

/home/slaughter/trelis/help/Trelis_User_Help/contents/assets/images/new_in_2020_2/reduce_panel.png

Figure 6:

The new reduce command (described below) uses a new command panel to rapidly set up parameters to simplify and assign boundary conditions to bolt connectors. Access the Reduce options in the command panels by clicking on Mode/Geometry > Entity/Volume > Action/Modify and using the dropdown to select Reduce.

1.1.7.2 Meshing
1.1.7.2.1 New Meshing Collapse Commands

The following commands are good for collapsing low quality tets and triangles. The user specifies a mesh entity to collapse and optionally a metric. The operation attempts to collapse the mesh entity, ensuring that the quality of surviving neighbor mesh entities does not degrade lower than the mesh entity getting collapsed. The specified metric is used to determine quality. If not specified, "Scaled Jacobian" is used.

If the collapse can not be done without degrading quality, no collapse is performed. To collapse triangles, use the first two commands.

Only triangle and tets can be collapsed, not faces and hexes.

collapse edge <id> [scaled jacobian|aspect ratio|shape|shape and size] collapse tri <id> [scaled jacobian|aspect ratio|shape|shape and size] collapse tet <id> [altitude|aspect ratio|aspect ratio gam|distortion|inradius|jacobian|normalized inradius|node distance|scaled jacobian|shape|shape and size|timestep]

/home/slaughter/trelis/help/Trelis_User_Help/contents/assets/images/new_in_2020_2/collapse.png

Figure 7:

1.1.7.2.2 Enhancements to Meshedit Command

The [keep node<id>] option indicates which node to collapse the edge to. The [compress_ids] option was also added to preserve the previous behavior of compressing the mesh id space after the collapse.

meshedit collapse edge <id> [keep node <id>] [compress_ids]

1.1.7.2.3 Mesh Intersection Group Naming

A new option was added to the find mesh intersection command to allow naming the group created containing the intersecting mesh. If no group name is specified, the group is named mesh_intersect for 3D elements and surf_intersect for 2D elements.

find mesh intersection {block|body|surface|volume} <id_list>> [with {block|body|surface|volume} <id_list>] [low <value=0.0001>] [high <value=0.0001>] [exhaustive] [worst <num_worst>] [draw] [log] [group <’name’>]

1.1.7.2.4 Normalized Inradius Metric for tet10 Elements

A new quality metric normalized inradius is now included as a standard option for all quality commands that affect tets and tris. It is intended to measure quality of TETRA10 and TRI6 elements, but can also measure linear (TETRA4, TRI3) elements. While most tet metrics, such as the default Shape, only take into account the 4 corner nodes of the tet, the normalized inradius uses the ten nodes of the tet. This is especially useful when measuring quality for a coarse tet mesh at curved surfaces where mid-edge-nodes can be projected to geometry distorting the elements. An example of using the new metric in a command to display the mesh quality is as follows:

quality volume all normalized inradius draw mesh

1.1.7.2.5 New Node Constraint Options

When tet meshing with TETRA10 elements or setting a block element type to TETRA10, the mid-edge nodes on the surfaces can be projected to follow the geometry. In some cases, those projections can form an invalid or poor quality element when the linear version of the elements would otherwise be acceptable. Previously, Cubit provided the set node constraint command to control mid-edge node projections. The smart option allows for projections only if element quality does not degrade below a quality threshold. This version provides a new tet quality parameter and threshold parameter.

set node constraint [on|off|smart][tet quality [distortion|normalized inradius]] [threshold <value=0.15>]

With the introduction of the normalized inradius metric in this release, the tet quality setting can use this new metric as criteria for projecting mid-edge nodes. The new threshold value permits setting of a value at which mid-edge nodes will be straightened if the quality falls below. The node constraint options can also be set in the Options or Preferences dialog under Mesh Defaults and can be saved between Cubit runs.

1.1.7.2.6 Parallel Tetrahedral Meshing

With this release, users have access to MeshGem’s parallel tet mesher, TetraHPC. Parallel tet meshing is an option in the Tet Mesh Command panel mentioned above. Parallel tet meshing is threaded and will support up to 8 concurrent threads.

1.1.7.3 Geometry
1.1.7.3.1 Reduce Command

The reduce command prepares a bolt for analysis by quickly breaking down its geometry into its simplest form and applying boundary conditions. The different options allow the bolt to be simplified, decomposed into its component parts, overlap removed and fitted to surrounding geometry, imprinted and merged with surrounding geometry, meshed with a qtri scheme on the plug volume, and more. The full command syntax for the command is:

reduce {volume<ids>} [fit_volume] [webcut [{head|shank|both}]] [imprint] [merge][qtri] [increment_block_ids] [summary] [diameter <value>] [group_id{<value>|default}] [group_name {<string>|default}] [head_block_id{<value>|default}] [head_block_name {<string>|default}] [shank_block_id{<value>|default}][shank_block_name {|default}] [plug_block_id{<value>|default}] [plug_block_name {<string>|default}] [bolt_block_id{<value>|default}] [bolt_block_name {<string>|default}]

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Figure 8:

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Figure 9:

1.1.7.3.2 Groups Persist across Webcut

When a volume or body of a group is split in a webcut operation, the resultant pieces of the webcut will also be in the group.

1.1.7.4 Sculpt
1.1.7.4.1 HTET Unstructured Option

Sculpt now provides an option for splitting hexes into tets using an unstructured method where each hex is subdivided into six tets. Previously only the structured approach was available which split each hex into 24 tets.

1.1.7.4.2 Thicken Void

A new option for ensuring physical separation between elements of different material blocks is now provided. The new thicken_void option will insert elements designated as the void block material where non-void blocks would otherwise be in contact.

1.1.7.4.3 Better Fitting STL

Using the capture=5 option in Sculpt, mesh is fitted to the input STL. Sculpt now associates the grid edges of the reference mesh to the STL curve geometry. This is an extra level of association, in addition to the grid faces associated to the STL surface geometry. The result is better conforming of the mesh to the STL.

1.1.7.4.4 Color Smoothing Improvement

Color smoothing (spot optimization) in sculpt now extends smoothing out one additional layer of nodes after the first smoothing iteration, ensuring better quality.

1.1.7.5 Graphics, Utilities, etc.
1.1.7.5.1 Enhancements to Free Entity Selection

The ability to select free surfaces (sheet bodies) has been added to the command:

select free [surface <id_list>] [curve <id_list>] [vertex <id_list>] [add|remove]

1.1.7.5.2 No More Highlight Color Collisions

The automatic colors that Cubit assigns to entities have been slightly changed to avoid colors that are too close to the highlight color, which previously made it difficult to see what was highlighted.

1.1.7.5.3 Case Insensitive Names

When naming entities in Cubit, names are now case insensitive.

1.1.7.5.4 New HDF5 file type supported

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Figure 10:

A new file type for saving the state of the Cubit model has been introduced in Cubit 2020.2. The new file type is .cub5.

The contents and structure of the new type is exactly the same as a .trelis file, but the extension name has been changed.

Beginning with Cubit 2020.2, users will be able to read in .trelis files, .cub5 files, and .cub files.

Users will be able to export .cub files and .cub5 files, but will not be able to export .trelis files. Over time, Coreform Cubit will deprecate support for .trelis files in favor of supporting only .cub and .cub5 files.

What are the motivations for this change?

1.1.7.6 Defects Fixed in Coreform Cubit 2020.2

Ref #

   

Description

2859

   

Draw curve all produces error on composited surface

3103

   

Extended selection *.py files not showing up on Mac

3485

   

Spurious warning on cub import

3710

   

Cubit slow to select with a long command string

3791

   

Draw command outputs commands when nothing to draw

4045

   

Dark mode on mac - model tree font matches the background color

4065

   

Model tree needs refresh event after import

4116

   

Crash - on merge all

4117

   

Draw vol not is_meshed produces ERROR if everything is meshed

4158

   

Nastran Export Issue

4310

   

Selecting free vertex, curves and surfaces with is_free

4440

   

Crash in RelWithDebInfo mode on Windows

4504

   

SAW client has flashing graphics on Windows

4519

   

Case sensitivity not respected in new parser help strings

4609

   

MGT Function

4615

   

Unique_genesis_ids not working with import ’filename.cub’

4632

   

Change to fire ray output

4646

   

Have an explicit option to name a new group

4648

   

Bug with list geometry after volume regularization

4691

   

Old attributes remain when importing cub file

4694

   

Update get_total_bound_box documentation

4695

   

Node moving (smoothing) bug in Cubit 15.6

4697

   

Bug with selecting entities in Cubit 15.6

4701

   

group_names_ids() missing from documentation

4703

   

Crash - get_sub_elements

4737

   

Nastran exporter broken since 15.4

4740

   

Segfault in Cubit python module when importing an exodus database

4743

   

Extraneous Command Output for volume copying

4747

   

Add query for material types for all blocks in a Cubit session

4755

   

Update netcdf

4768

   

Selection not recognised in batch mode

4772

   

Python 3.7 with Cubit-alpha - error loading shared object

4774

   

Draw command outputs commands when nothing to draw

4786

   

Equivolume and equiangle unrecognized

4787

   

Documentation update - Mesh Refinement

4835

   

Bug in splitting surface using close_to

4864

   

Typo when trying to export quality metric from a lite mesh

4866

   

Crash - tetmeshing with MeshGems 2.11

4959

   

Performance issue with recent merge of parser changes

4974

   

Misplacement of higher-order mid-face nodes during smoothing

 

   

Avoid generation of a new volume in surface removal on multiple shell volume

 

   

simplify command respects vertices now. Not respected previously

 

   

Hardlines can now be parsed with num_parents=1

1.1.7.7 Other Enhancements to Coreform Cubit 2020.2

Ref #

   

Description

205

   

Cannot have return carriages within for loops in a Cubit python script

380

   

Keep volume in group after a webcut and reflections

618

   

Exodus-based surface mesh sizing by function

660

   

Select surface based on angle

3528

   

Sierra mesh_scale to use more updated version of Cubit

3535

   

Update Cubit component snap shot in Sierra repository

4627

   

Create standalone Sculpt CMake for Alegra

 

   

STL import performance improvement

 

   

Import Mesh-basd geometry performance improvement on models with large sidesets

 

   

Enhanced meshing of composites. Better underlying faceting from ACIS

 

   

Improved robustness in blunt tangency command

 

   

topology check coincident node works off absolute distance instead of distance between bounding boxes

 

   

Fix for inability to create group in quality command using node distance metric

 

   

Allowing blocks to persist through unite operation with include_mesh option

 

   

Support Dark Mode

 

   

Add a command panel navigation method that minimizes wasted vertical space

1.1.7.8 Limitations Introduced in Coreform Cubit 2020.2

Ref #

   

Description

3433

   

Superelement export not supported

 

   

Cubit is not supported on RHEL6 machines