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CUBIT Toolkit

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CUBIT 14.0 Release Notes

CUBIT 14.0 Logo
 

Product Description

New Features CUBIT 14.0

CUBIT 14.0 Documentation

Product Highlights

Limitations CUBIT 14.0

CUBIT 14.0 Contents of Release

Contact Information

Defects Fixed CUBIT 14.0

Platforms Supported

 

Known Defects CUBIT 14.0



 

Product Description

CUBIT is a full-featured software toolkit for robust generation of two- and three-dimensional finite element meshes (grids) and geometry preparation. Its main goal is to reduce the time to generate meshes, particularly large hex meshes of complicated, interlocking assemblies.

 

Product Highlights

Meshing: CUBIT is a solid-modeler based preprocessor that meshes volumes and surfaces for finite element analysis. Mesh generation algorithms include quadrilateral and triangular paving, 2D and 3D mapping, hex sweeping and multi-sweeping, tet meshing, and various special purpose primitives. CUBIT contains many algorithms for controlling and automating much of the meshing process, such as automatic scheme selection, interval matching, sweep grouping and sweep verification, and also includes state-of-the-art smoothing algorithms.


Geometry Preparation: One of CUBIT's strengths is its ability to import and mesh geometry from a variety of CAD packages. CUBIT currently integrates the ACIS and Catia geometry kernels directly within its code base, allowing direct manipulation of the native CAD geometry format within CUBIT. This reduces the errors and anomalies so often associated with geometry translation. CGM (Common Geometry Module) also boasts a facet-based geometry kernel developed at Sandia that can be used for remeshing or editing old mesh files or models defined by triangle facets. In addition, CUBIT has developed a comprehensive virtual geometry capability that permits local composites and partitions to geometry without modifying the underlying native geometry representation. The user can choose to ignore, clean-up or add features to the model allowing greater flexibility to meshing algorithms to generate better quality elements.


CUBIT Environment: CUBIT has developed both a convenient command line interface with an extensive command language as well as a polished graphical user interface environment. The GUI is based upon the cross-platform standard QT, which allows the same look and feel on all supported platforms. Also included is a graphical environment based upon the VTK graphics standard which has been optimized for display and manipulation of finite element data and geometry. Fast, interactive manipulation of the model is a tremendous advantage for models with thousands of parts or millions of elements.


For more information on CUBIT, including licensing arrangements and terms see the CUBIT website http://cubit.sandia.gov

 

New Features in CUBIT 14.0

Index of New Features

Meshing



Geometry



Import/Export



Graphics, Utilities, etc.



Misc





Meshing



Global Element and Node Ids


New to CUBIT 14.0 is full support for the Element and Node Id Maps in the Exodus file format. This means that for the first time CUBIT users will be able to track nodes and elements through the entire analysis process using a single consistent set of Ids.


In version 14.0 when either an element or an element's owning geometry is placed into an element block, the element is assigned an additional id called the Global Element Id. Global Element Ids are exported to the Genesis/Exodus file as the Exodus Global Element Id. A new set of commands: "draw element <id>", "locate element <id>", "list element <id>", etc., has been added to allow the user to to identify an element by its Global Id. Global Element Ids are also visible in the Properties Page in the GUI. As in previous CUBIT versions, when an element is created it is still given a hex id, tet id, face id, tri id, etc.


CUBIT node ids are also exported as Global Node Ids in the Exodus file, so nodes can be located in CUBIT using the Global Node Id in commands such as "locate node <id>", etc.



Paver improvements to reduce small edges


The Paving algorithm has been improved to remove small edges in cases where two 3-valent nodes are close together in the mesh. This can be especially helpful when having small edges in the mesh would drive up analysis run-times. An example of the improvements is shown in the following figures.


Before Changes After Changes

Version 13.2 mesh

Improved version 14.0 mesh



Fix for random dense mesh in Skeleton Sizing


When using Skeleton Sizing, sometimes the resulting mesh may exhibit locally dense regions. This tends to occur on complex models with regions of high curvature. To avoid this problem, a new option, facet_extract_ang, has been added to the skeleton sizing command. This option gives control of the accuracy of a faceted approximation of the model used to compute the adaptive sizing. The default value for this option is 10 degrees. For models with high curvature regions, decreasing the tolerance will give a better approximation of the geometry and avoid the creation of random dense meshes. Note that increasing this angle too much can generate invalid facets over curved regions, while decreasing the angle too much can cause significant slowdowns in sizing calculations.


Skeleton sizing on surfaces:

Surface <surface_id_range> Sizing Function Skeleton
{[scale <1 to 10 = 7>] [time_accuracy_level <1 to 3 = 2>]
[min_depth <3 to 8 = 5>] [max_depth <4 to 9 = 7>] [facet_extract_ang <1 to 30 = 10>]
[min_num_layers_2d < 1 to N = 1>] [min_num_layers_1d < 1 to N = 1>]
[max_span_ang_surf <5.0 to 75.0 = 45.0 degrees>]
[max_span_ang_curve <5.0 to 75.0 = 45.0 degrees>]
[min_size <float>] [max_size <float>] [max_gradient <float=1.5>]}


Skeleton sizing on volumes:

Volume <range> Sizing Function Skeleton
{[scale <1 to 10 = 7>] [time_accuracy_level <1 to 3 = 2>]
[min_depth <3 to 8 = 5>] [max_depth <4 to 9 = 7>] [facet_extract_ang <1 to 30 = 10>]
[min_num_layers_3d < 1 to N = 1>] [min_num_layers_2d < 1 to N = 1>]
[min_num_layers_1d < 1 to N = 1>]
[max_span_ang_surf <5.0 to 75.0 = 45.0 degrees>]
[max_span_ang_curve <5.0 to 75.0 = 45.0 degrees>]
[min_size <float>] [max_size <float>] [max_gradient <float=1.5>]}



Refine Parallel Enhancements


The Refine parallel command can now refine mesh to geometry in cases where the mesh and geometry were created outside of CUBIT. This includes cases where the mesh represents a simplified geometry and does not match the model geometry one-to-one. Where possible, an association between the mesh and the model geometry is calculated. This association allows mesh refinement to accurately "follow" the geometry as the mesh is refined.


To display the calculated association between mesh entities and geometric entities, the Refine Parallel command creates three types of groups for each mesh entity type (edge, tri, and quad). The first group contains mesh entities where a unique 1:1 map exists between the mesh entity and geometric entity. The second group contains mesh entities that are associated with multiple geometric entities. The third group contains mesh entities not associated with any geometric entity.


Refine Parallel [Fileroot <'root filename'>] [Overwrite] [No_geom] [No_execute] [Processors <int>] [Numsplit <int>] [Version <'Sierra version'>]



Regular Triangle Refinement Setting


The default behavior of triangle refinement attempts to maximize element quality using the basic one-to-four template. This can sometimes result in an irregular refinement pattern, where one or more edges are swapped. To enforce regularity of the triangle refinement pattern, regardless of quality, the following setting may be used. The default value for the setting is "OFF".


Set Triangle Refine Regular {on|OFF}



New Skinning Options


Two options were added to the skinning command (command syntax shown below). The Individual keyword tells CUBIT to skin Blocks or Volumes one by one independently of each other, even if they share merged surfaces. The Nomake keyword tells CUBIT to not create any kind of grouping of the mesh faces resulting from the skinning operation.


Skin {Block|Volume} <range> [Individual] [Nomake]

Skin {Hex|Tet|Block|Volume} <range> [Nomake]




Geometry



ACIS Version 22.2


CUBIT 14.0 contains an upgraded version of ACIS: version R22 SP2. This new version of ACIS contains various improvements and bug fixes. As with any upgrade to the ACIS solid modeling kernel there is the potential for minor geometry id changes in CUBIT.



Uniting Meshed Volumes


CUBIT 14.0 contains a new capability for uniting meshed volumes. This allows the user to decompose the geometry for meshing purposes and then reunite it after it is meshed. One of the big benefits of doing this is that the user can then smooth the mesh without worrying about the artificial boundaries that were introduced when decomposing the volume for meshing. The example below shows how this was done and the significant improvement in mesh quality resulting from being able to smooth the mesh on a single united volume.


Before uniting:

Pipe 1 before uniting

Pipe 1 before uniting


After uniting:

Pipe 1 before uniting

Pipe 1 before uniting

To use the new capability use the "include_mesh" option in the Unite command:


Unite [Volume|BODY] <id_range> [With [Volume|BODY] <id_range>] [include_mesh]



Webcutting with Cones


A new command has been added to perform webcuts with conical surfaces. The conical surface is defined by two radii at two locations, where the locations also define the axis fo the cone. The command syntax is:


Webcut {Volume|Body|Group} <ids> [With] cone radius <val> <val> location {options} [Imprint] [Merge] [group_results] [preview]




Import/Export



Tie Constraints


A Tie Constraint can be used to tie the elements of one sideset to the elements of another. Currently, only the Abaqus Exporter supports this type of constraint. The commands to create and modify Tie Constraints are:


Create Constraint Tie [name "<name>"] master sideset <id> slave sideset <id>
Modify Constraint <id> [master sideset <id>] [slave sideset <id>]
Delete Constraint <id>




Misc



Renumber Command now handles Global Element Ids


The Renumber command has been updated to support renumbering global element ids. Any valid global element id range specification can be used to specify the source ids. There is no requirement that the ids being renumbered are consecutive. The new id numbers will be consecutive beginning at the specified start id.


Renumber {Element} <id_range> Start_id <id>



Number of allowed Block Attributes increased


CUBIT now allows up to 20 attributes to be assigned per block. Each block has a default number of attributes, depending on the element type assigned to the block. The number of attributes that can be assigned to a block can be increased up to 20 attributes with the command:


Block <id_range> Attribute Count <1-20>


Once the number of block attributes has been set, individual attribute values may be set using the following command:


Block <id_range> Attribute <value>



New APREPRO Functions


Two new APREPRO functions have been added to support looping through entities in a CUBIT group.


NumTypeInGroup("group_name", "entity_type")


This function returns the number of entities of type "entity_type" in group "group_name". Acceptable entity types include: "body", "volume", "surface", "curve", "vertex", "node", "edge", "quad", "face", "tri", "hex", "tet", "wedge", or "pyramid".


GroupMemberId("group_name", "entity_type", index)


This function returns the ID of the entity of type "entity_type" in the group with name "group_name" at the specified index. If the group contains multiple entity types the index will only be relevant for the entity type specified and will behave as if the group only contained that entity type. Acceptable entity types include: "body", "volume", "surface", "curve", "vertex", "node", "edge", "quad", "face", "tri", "hex", "tet", "wedge", or "pyramid".


An example of how these two functions would be used together to loop through all of the surfaces in a group is shown below.


#{_num_surfs = NumTypeInGroup("some_group", "surface")}
#{_cntr=0}
#{Loop(_num_surfs)}

#{_surf_id = GroupMemberId("some_group", "surface", _cntr)}
draw surface {_surf_id}
#{_cntr++}

#{EndLoop}




Graphics, Utilities, etc.



Visualizing Shell Thickness


New options have been added to the 'draw block' command, allowing users to visualize element block thickness on SHELL and TRISHELL type element blocks. The user can visualize thickness by color, where each block is drawn in a specific color according to thickness, with a corresponding color bar. Or blocks can be drawn with their specified thickness, so they visually have a thickness. This thickness can also be scaled in the draw command. Additionally these SHELL and TRISHELL element blocks can draw with their normals, allowing orientation to be verified.


Draw Block <block_id_range> [thickness [offset [scale <val>]|include_normal]] [Color <color_spec>] [add]



Draw Locations, Lines, and Polygons


In some cases it may be useful to simply draw a location, line or polygon to the screen to help visualize some aspect of the model. Locations, lines and polygons are not geometry or mesh entities and are only visible until a refresh or display command is issued. Multiple draw commands can be buffered using the no_flush option on each draw command in the series, followed by a graphics flush command.


Draw Location {options}... [color <color_name>][no_flush]
Draw Line Location {options} Location {options} ... [color <color_name>][no_flush]
Draw Polygon Location {options} Location {options} Location {options} ... [color <color_name>][no_flush]



Limitations in CUBIT 14.0


No known limitations.  


Fixed Defects in CUBIT 14.0


The following items are the user-reported bugs fixed since last release of CUBIT. For more information contact Byron Hanks (bwhanks@sandia.gov).


Ref #

Resolved Defect*

9292

When a user starts an installed version of CUBIT by double clicking an icon the start up directory is potentially set to an area that the user does not have write access permission. The new behavior now opens the journal file in the users home directory if it is unable to open the file in the start-up directory.

9463

When two surfaces in a volume share two adjacent curves you would sometimes get extra quad faces exported in a sideset.

9430

During "football" cleanup in the paver there would sometimes be a crash.

9428

CUBIT crashes in webcut when collinear points are input to specify a plane.

9421

Hex refinement crash.

9413

There used to be a fallback scheme such that scheme trimesh tried tridel, triadv, then tripave. That fallback is not working correctly anymore. Thus users have models that have some surfaces that fail to mesh. However, if they manually set the surface to triadv and try again it meshes correctly.

9403

Cub file save failure with graphics off.

9398

CUBIT crashes when saving a cub file of a simple geometry.

9348

Copy reflect group_results crashes.

9337

Sideset WRT Vol del crashes CUBIT.

9326

CUBIT hangs opening .cub file if the power tools window is on.

9325

File imports w/ warnings, then crashes when setting sweep scheme.

*The defects listed above are only those user-reported issues deemed "critical" or "blocker". For information on other resolved defects contact Byron Hanks.

 

Known Defects in CUBIT 14.0


The following items are bugs or limitations that may be encountered in the current release of CUBIT. For more information on these defects or to report additional defects contact Byron Hanks (bwhanks@sandia.gov).


Ref #

Known Defects in CUBIT 14.0*

Description

Suggested Work-around

N/A N/A N/A N/A

*The defects listed above are only those user-reported issues deemed "critical" or "blocker". For information on other known defects contact Byron Hanks.

 

Documentation Updates


The CUBIT 14.0 online documentation may be found here. Both a PDF version and a Microsoft Word version are also available for download. The CUBIT GUI installation also includes the full user documentation included with the program. The user's manual may be accessed from the Help menu.

CUBIT 14.0 Contents of Release


CUBIT Program
: The installation package includes executables and libraries, packaged in tar.gz files for Linux machines. For Windows, the package is in a self-installing executable, and for Mac OS X a .dmg file is provided. Both a command line and GUI version of CUBIT are included with the installation package for all platforms.


Documentation: Linux, Windows and Mac versions include full online documentation. Windows also includes .chm (Windows Help File), of the complete documentation that can be run separately from CUBIT.


 

Platforms Supported


CUBIT 14.0 supports the following Platforms:


  • Linux RedHat Enterprise 5, 32- and 64-bit

  • Windows 7, XP, Vista, 32- and 64-bit

  • Mac OS X Intel based (10.4-7)


Non-Sandia Users

CUBIT is freely available for United States government use. For more information on licensing CUBIT, including academic, commercial, and all other use, go to our licensing page. For current CUBIT users, CUBIT 14.0 may be downloaded from the CUBIT download page.

Sandia Personnel Only

Windows
In the dropzone directory \\dropzone\public\cubit\Win32 or \\dropzone\public\cubit\Win64 you may download a Windows installation file. Either copy the file for the version you require to your hard drive then double-click to install, or simply double-click on the file in the dropzone.
MAC OS X
Download a Mac OS X disk image file from the dropzone. Go to the following directory \\dropzone\public\cubit\Mac32. Copy the file Cubit-14.0-Mac32.dmg.gz to your Mac harddrive. Use gunzip to unpack the disk image file.
LINUX LANS
Check with your local LAN administrator for instructions on how to access CUBIT on your local LAN. In most cases typing one of the following commands at the UNIX prompt should allow you to execute CUBIT.  In some cases, the full path will need to be specified:
/projects/cubit/<cubit_command>

cubit

64-bit Version 14.0 with GUI. The latest released version of CUBIT deployed to the LAN

cubit32

32-bit Version 14.0 with GUI. The latest released version of CUBIT deployed to the LAN

cubit -nogui

64-bit Version 14.0 Command Line only with graphics window

cubit -nogui -nographics

64-bit Version 14.0 Command Line only without graphics window

cubit-14.0

64-bit Version 14.0 with GUI

cubit32-14.0

32-bit Version 14.0 with GUI

cubit-beta

Version 14.1 beta. The latest beta version still in development

 

Contact Information


CUBIT Help

For general technical questions including download, installation and CUBIT technical assistance.
cubit-help@sandia.gov

CUBIT Licensing and Passwords

Charis Church
Cubit Licensing
Phone: 505-284-6464
Email: cchurch@sandia.gov

CUBIT Support Lead

Bob Kerr
Cubit Support Lead
Phone: 505-844-8606
Email: cubit-support@sandia.gov

CUBIT Project Lead

Byron Hanks
Sandia National Laboratories
Computational Simulation Infrastructure (org. 1543)
Phone: 505-845-0500
Email: bwhanks@sandia.gov

Web site contact: Cubit Support