CUBIT 10.1 Release Notes

Product Description

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 geometry kernel directly within its code base, allowing direct manipulation of the ACIS native CAD geometry format within CUBIT. This reduces the errors and anomalies so often associated with geometry translation. CGM 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 CUBIT 10.1

CUBIT 10.1, released March 2006, incorporates the following new features:

	Meshing		Geometry		GUI		Properties and Support
Create Nodes/Elements Delete Nodes/Elements Node Equivalence Node/Element Renumbering Smart Laplacian Smoothing Mesh Sizing for Assemblies Mesquite Upgrade Tetmesh Respect		Tolerant Imprint Simplify Tool Collapse Curve Collapse Surface Midsurface Tool Tweak Operations Multi-volume attributes Remove Individual Surfaces		Interactive Node Movement F1 Context Help Advancing Pickwidgets New GUI Panels Vertex Type Editor Create Beam Panel Geometry Power Tool Enhancements Property Panel Enhancements Tree Window Enhancements History Window Journal File Editor Enhancements Options Enhancenments New Graphics Window Features Others		Metadata Enhancements Consistent Node IDs on Import Patran Mesh and BC Export Dyna3D Mesh Export Abaqus High Order Elements Sleep Command Comment Command Documentation Enhancements 64 Bit Linux Support

Meshing

Create Nodes/Elements: Cubit's mode of operation until now has always been geometry-centric. That is, all nodes and elements must have a geometry "owner". For example, a node must be owned by a vertex, curve, surface or volume, based upon where it is located in the mesh. Cubit could not create nodes that were independent of geometry. With version 10.1, Cubit introduces a new element-centric paradigm, where nodes and elements can be created and deleted independent of geometry. The new create node and element commands are basic utility operations that provide bottom-up creation capabilities for mesh entities. They are especially useful for making small edits to an existing mesh that has already been created using traditional Cubit meshing schemes.

Triangle elements were deleted from mesh and new elements created using new tools in Cubit 10.1

Delete Nodes/Elements: As a complement to the new element-centric capability described above, Version 10.1 introduces the ability to delete individual nodes and elements from a mesh independent of geometry. This includes the ability to delete elements from a mesh that has been built using geometry-centric meshing schemes. This capability is also useful for making small edits to an existng mesh.

Node Equivalence: Previous versions of Cubit provided capability to merge meshes on coincident curves or surfaces that have topologically identical meshes. This capability relied on the geometry and mesh being identical prior to merging. Cubit 10.1 introduces an element-centric form of the merge operation, where individual nodes may be merged independent of their geometry ownership. This operation permiits the user to select two arbitrary nodes in the mesh to be merged or "equivalenced". It is intended as a basic utility operation that could be used in conjunction with the more powerful geometry-centric merging tools.

Node and Element Renumbering: Cubit 10.1 introduces the ability to renumber sets of nodes and elements based upon a starting node or element ID. For example, an arbitrary set of nodes may be selected in the mesh and a starting node number applied. Cubit will renumber the nodes, provided no ID collisions occur. Nodes and elements can also be renumbered based on geometry ownership. For example, all elements in a given volume may be renumbered starting with a specific user defined element ID.

Smart Laplacian Smoothing Scheme: The Smart Laplacian Smoothing scheme has been added to Cubit in Version 10.1. This is a fast method for improving node placement that guarantees that element quality will not get worse when applied. The traditional Laplacian smoothing scheme in the vast majority of cases will improve element quality, however in some isolated cases the element quality may degrade. The Smart Laplacian smoothing scheme addresses this deficiency while maintaining the same performance.

Auto Mesh Sizing for Assemblies: Introduced in Cubit 10.0, the automatic geometry-based mesh sizing provides the ability to generate an automatically graded tetrahedral mesh based upon the characteristics of the geometry. In 10.1 this capability is extended for use with assemblies, where nearby geometric features are taken into account even if they are not part of the same volume.

Mesquite Upgrade : The Mesquite component library is used by Cubit for smoothing and mesh quality improvement. It is an open source library independently developed at Sandia. The latest Mesquite library has been incorporated into Cubit in an effort to maintain current in this important technology.

Tetmesh Respect: When using tetrahedra, it is sometimes useful to define specific locations on the interior of the volume where nodes will be located. Although this feature has been supported in the past, this command has been expanded in this release to permit input of a file, where multiple node location may be specified.

Back to New Features

Geometry

Tolerant Imprint: The tolerant imprint command adds a new option for imprinting volumes. The standard imprint command can often introduce small surfaces (slivers) or other unintended features into the model. This can be troublesome when trying to mesh, requiring additional geometry cleanup operations. The tolerant imprint operation uses a new tolerant operation to ensure most of these problems are never introduced. The tolerant imprint operation is a new command and does not repace the old imprint operation. The existing imprint operation continues to support indivual vertex, curve, surface and volume imprinting operations, while the tolerant imprint operation supports only volumes.

 
Tolerant imprinting used to avoid creation of sliver surfaces.
Resulting mesh shown after tolerant imprint.

Simplify Tool : The new simplify tool provides an automated way to quickly composite surfaces in a model that may not be important to the analysis model. This new tool will examine the angle between all surfaces in the given volumes or surfaces and look for surfaces that can be composited. A feature angle can be defined to control which curves will be eliminated. Additional control is provided so that individual user-defined curves and surfaces that don't meet the angle criteria, may also be preserved.

Collapse Curve: This new virtual operation can remove very small curves from the model that can effect the quality of the mesh. This is accomplished by collapsing the two vertices of a curve into a single location. The geometry of attached curves remains unchanged with the exception of the relocated end vertex. This functionality is especially useful when used with the Geometry Power Tool. Small curves can be located and the collapse curve operation can be performed by right-clicking on the curve and using the colapse curve operation in the menu.

  
A small curve is eliminated using the collapse curve operation

Collapse Surface: The new collapse surface command is a virtual operation that combines a partition and composite operation into a single operation. This is useful for modifying surfaces such as fillets by partitioning them along their axis and combining the resulting two surfaces with their neighbor. This operation can also be accessed from the Geometry Power Tool through the context menu when selecting surfaces.

  
Before and after using the collapse surface operation

Midsurface Tool: A new tool for generating surfaces midway between two existing surfaces has been added. This tool permits the user to select pairs of surfaces between which a new surface will be generated. The surface will be clipped by the enclosing body. This comand will work for planar surfaces and for anaylitic surfaces such as cylinders and spheres that have concetric axis.

Tweak Operations: Several new tweak operations have been added for vertices and curves. These operations are particularly useful when dealing with sheet bodies, such as those produced from the midsurface tool. The tweak curve extend option has been added for sheet bodies to permit a surface to be extended to meet another surface. The remove curve option will allow the user to remove a curve from the interior of a surface much the same way the remove surface command will work in 3D. A chamfer option has also been added to the tweak vertex command, allowing a chamfer to be introduced on 2D and 3D models at a specified vertex.

Multi-volume Attributes: when list geometry (for example: list volume 1 2 3), Cubit will now provide the centroid and total volume of all volumes in the command.

Remove Individual Surfaces: The remove surface comand now has the option to perform operations on one surface at a time rather than on all surfaces simultaneously that are listed in the command. This permits the user to perform the command on a whole range of surfaces even though some may not be successful. Those that are possible, it will perform the operation. Error messages will be issued for those where it did not succeed.

Back to New Features

GUI

Interactive Node Movement: The move node panel now supports the option to interactively move one or more nodes by dragging the cursor. Nodes can be selected and moved anywhere in the screen parallel to the viewing plane, or may be constrained to lie on the owning geometry. A special option for displaying mesh quality will also paint neighboring elements based on current local element quality metrics and will update as the node is moved.

F1 Context Help: The F1 key will now bring up the user documentation. based on the current cursor location, the documentation will open to the applicable page.

Advancing Pickwidgets: In command panels that contain multiple fields where entity IDs may be entered, a middle mouse button click in the graphics window will advance the focus to the next field. This reduces the need to move the cursor back to the command panel to click on a new field.

New GUI Panels: New Panels support the new features for 10.1 have been added. This includes support for the simplify tool, collapse curve and surface commands, tolerant imprint, tweak curve and vertex options, create and delete nodes and elements, node and element renumbering and node merging.

Vertex Type Editor : The surface mapping and submapping meshing schemes utilize vertex types to define the overall topology of the mesh. Vertex types include end, side, corner and reversal. Although Cubit's automatic algorithms generally select vertex types that provide the optimal mesh topology, it may be sometimes necessary to select an alternate mapping or submapping mesh topology. This new widget, located in the mapping and submapping scheme advanced options, provides an interactive interface for defining vertex types.

Create Beam Panel: In some cases it is useful to define beam elements between existing nodes in a mesh. The new Create Beam Panel provides the option to interactively select nodes to create beam elements. No underlying geometry is required. The existing spider command in cubit is used to create the beams, therefore it also provides options for quickly defining sets of beam elements between a node and surface and a node and element face.

Geometry Power Tool (GPT) Enhancements: The geometry power tool provides extensive capability for diagnosing potential problems and repairing geometry. Cubit 10.1 introduces several new capabilities:

Curve and Surface Collapse: The new collapse curve and surface operations are now supported in the GPT. The context menu when selecting curves or surfaces now provides the option to use these commands.

Mergable Diagnostics: A new diagnostic test that examines each entity to see if it can be merged with another entity has been added. When executed, a list of pairs of mergable curves and surfaces will be displayed. Each pair can be graphically interogated and the new merge pair context menu applied to merge the entities.

Merge All: All mergable entities can now be merged directly from the GPT using the merge button or context menu when selecting mergable pairs.

Persistent Diagnostic Tests: Diagnostic tests to be performed can be selected in the GPT. The selected set of tests will now be saved between runs of Cubit.

Highlight All: When selecting the parent node of any group of entities in the GPT tree window, the highlight all context menu item is available. This provides the option to quickly highlight all entities with the same characteristic. For example, it could be used to highlight all blending surfaces in the model or all mergable entities.

Remove All: The remove all button provides the option to perform the remove surface command on all surfaces in the small surface category.

Mulitple Locate: The locate context menu option can now be performed when multiple entities are simultaneously selected.

Property Panel Enhancements: The property panel, introduced in Cubit 10.0, lets the user view all attributes of a selected entity and edit them directly in one location. Several new capabilities have been added to the property panel for Cubit 10.1:

Multiple Entity Support: The property panel has been enhanced to effectively handle multiple entity selections. This allows for faster editing of mutiple entities that may have similar attributes. Attributes that may be unique for a given entity, such as the name, are not editable when multiple entities are selected, however attributes such as color, mesh size and meshing scheme may be set, changing all selected entities simultaneously.

Assembly Support: Selecting entities in the new assembly tree will cause the property panel to be populated with applicable attributes. DART Metadata can now be viewed and edited directly in the property panel.

Boundary Conditions - Shell Use: The shell use property has been added to the property page when selecting a sideset.

Tree Window: The Tree window displays the hierarchical representation of the model currently in Cubit. It also shows a graphical representation of groups and boundary conditions currently defined. Cubit 10.1 introduces the foloowing new features in the tree window:

Interactive Boundary Condition Editing: Nodesets, sidesets and blocks may be displayed and edited in the tree window. Cubit 10.1 adds the capability to graphically select entities to be added to an existing boundary condition. By first selecting the common entities to be added, and then right clicking on the boundary condition in the tree and selecting the add selected to.. option, boundary conditions may be quickly populated.

Assembly Tree: A new assembly tree hierarchy has been added to the tree window. Assemblies may be quickly built and edited using context menus and drag-and-drop techniques.
The assembly tree represents the hierarchical assembly definition provided by a DART metadata file and will be populated automatically when a metadata file is read.

Boundary Condition Names: Names can now be applied to nodesets, sidesets and blocks. The specified names will be included as an attribute in the standard metadata file. (Note that the standard Exodus format does not support BC names, therfore this information will not be saved if the exodus format is used)

Locate and Fly-in: The locate and animated fly-in options have been added to the context menu when geometric entities are selected in the tree window.

Visibility Feedback: The tree window normally displays icons for all geometric entities in the current model. In Cubit 10.1 when an entity is made invisible, the icon next to the name of the entity will also be made invisible.

Picked Group: A permanent group called "picked" is now present under the Groups. This special group is reserved for adding entities directly from the graphics window using the right-click context menu. It can be used like a temporary buffer to hold collections of entities that are actively being worked on.

History Window: A new window located in the same place as the command line window, displays an ongoing history of all commands executed in the current session.
The tabs at the bottom of the command line window provide the mechanism for switching between these windows. Individual commands can also be executed directly from the history window.

Journal File Editor: The journal file editor provides a convenient way for creating and editing Cubit journal files. Several new enhancements have been added for Cubit 10.1:

Multiple files: The journal file editor now permits editing of mutiple journal files in separate window panes.

Import Options: The journal file editor provides several options for importing commands. In addition to the standard import from files, the editor can import the current contents of the history or command windows. It can also import the contents of the python script window.

Python/Cubit Preference: The journal file editor provides the option to edit commands using the python scripting language or with Cubit commands. The Options dialog provides the capability to remember the preferred mode for command editing

Options Dialog: The Options dialog has been updated to support most of Cubit's graphics options. This includes line color, faceting tolerance, silhoutte options, element shrink, lighting options and display of the triad. Default entity labeling options are now also supported.

Graphics Window Enhancements: The following new capabilities are now available in the Cubit Graphics Window:

ID numbers with preselection: The preselection feature displays a highlight over entities that can be selected as the cursor moves over them. The entity ID number is now displayed along with the highlight.

Rubber-band Selection Options: Dragging the cursor with the control key held down provides a quick way to select multiple entities. Cubit 10.1 adds the options for rubber-band selection to choose between selecting only entities completely included in the box or polygon, or including any entity that the box or polygon touches. A new option to choose between selecting all entites in the path of the viewing cone, or just those entities that are visible in the current view is also provided.

Multi-selection with rubber-band tool: The rubber band selection tool can be used with the combined control and shift keys if current selections are to be maintained. Any new selections will be added to the current selections.

Rotate About: The graphics window context menu option to rotate about the selected entity has been added. This option provides the ability to set the center of rotation at the centroid of the selected entity.

New Viewing Options: In addition to the standard Top, Front and Side Views, Cubit 10.1 additonally provides options for viewing Bottom, Back and Left Side Views.

Mesh Quality Scale: When displaying element mesh quality, a color legend now appears in the graphics window.

Mouse Wheel Zooming: The wheel on a standard wheel mouse can now be used for zooming transformations in the graphics window.

Add to Picked Group: A new context menu option in the graphics window has been added that adds the selected entity to the picked group. The entity will be appear in the picked group displayed in the tree window.

Reentrant Curve Refinement: When refining a mesh, the option has been provided in the refine curve panel to locate all curves meeting a defined angle criteria. This permits the user to preview curves in the model that could potentially generate poor analysis results due to a reentrant corner condition. The list of curves selected may be edited and used as input to the refinement commands.

Split Surface: The Split surface command provides the option to break up a surface based on several different criteria. One criteria is based upon a location. The split command panel now provides the option to graphically select a split location.

Back to New Features

Properties and Support

Assembly Tree: The standard Cubit Geometry Tree Window now incorporates an assembly tree view representing the hierarchy of the current assembly. The assembly tree will automatically be populated when reading any metadata file. The tree can also be interactively constructed by adding sub-assemblies and parts. Volumes can also be dragged and dropped from other parts of the tree to populate parts in the assembly hierarchy. Graphically selecting volumes in the graphics window and right clicking on a part will also provide the option to add to the part.

Metadata Property Page: Selecting an entity in the new assembly tree will also populate the Property Window. All metadata attributes of the selected assembly entity will appear and can be directly edited in this window.

DART 3.0 Specification: Cubit now supports the new standard metadata specification as defined by Sandia's DART Team.

Metadata Clean: The capability to delete parts that have been imported through metdata that do not have any associated geometry has been added. On export of metadata, the option to only export parts that have associated geometry is also provided.

Boundary Condition Names: Names can now be applied to nodesets, sidesets and blocks. The specified names will be included as an attribute in the standard metadata file.

Instance Numbers: Any metadata command that takes a part or asssembly name is now able to incorporate an instance number into its path string

Consistent IDs on Import: On import from Exodus format files, the node and element IDs will be maintained. Because of the unique nature of Cubit's infrastructure, previous versions of Cubit would not guarantee that the IDs defined in the Exodus file would be used in Cubit. Cubit 10.1 resolves this behavior and will report the IDs as they are ordered in the Exodus file. This is especially useful for interrogating a mesh where a specific node or element ID may have been reported in an analysis run.

Patran Mesh and BC Export: This release of Cubit now supports direct export of Patran format files along with basic boundary conditions. Where previously the utility "exopat" could be used for converting an Exodus mesh to a Patran mesh, the functionality of this basic utility has now been incorporated into Cubit.

Dyna3D Mesh Export: The finite element mesh may now be exported using the Dyna3D format. This release incorporates basic mesh entities including linear hex, tet, tri, quad, trishell, beams and bars.

Abaqus High Order Element Support: Cubit 10.0 introduced export of Cubit mesh and boundary conditions in Abaqus format. This release the format was extended to support tet10 and hex20 element types in Abaqus format.

Sleep Command: This command will pause the execution of a journal file for a given number of seconds.

Enhanced Comment Command: The Comment command is often used in journal files to documentary comments. This command has been enhanced so that aprepro variables and expressions will be evaluated and displayed. It also useful for previewing the significant figures of a numeric value as it will be written to the journal file.

"Quote" Aprepro Function: a new "quote" aprepro function has been added. It serves the purpose of putting quotes around a string in an aprepro expression. For example, it is useful for any Cubit command that requires quotation marks around a string such as file names and naming of entities when used in aprepro expressions.

Documentation Enhancements: The look and feel of the online Cubit documentation has been updated to improve efficiency, as well as several changes to the overall structure of the document. The full Cubit documentation is also now available as a pdf file that can be downloaded and printed.

64 bit Linux Support: Cubit now supports the 64 bit linux platform in its standard distribution.

Back to New Features

Limitations CUBIT 10.1

• Release 10.1 will be the last version that supports the HP-UX 11.x platform.
• The Granite Geometry Kernel is currently not supported on Linux or Mac OS. PTC will be releasing a Linux version and it should be available in subsequent releases. As of this release, PTC has not announced plans to support a Mac OS version of Granite.
• The Granite Kernel supports most of the commands and options used with the standard ACIS implementation in CUBIT. See the Granite documentation in the users manual for a description of differences between the CUBIT's supported options between Granite and ACIS.
• The Mac OS X version does not support the changing mouse cursors on pre-selection
• The Mac OS X version is still experiencing speed issues. 
• It is recommended that a 3-button mouse be used for the Mac OS X version since interactive transformation utilize all three buttons.
• As of Cubit 10.1 the following options have been reduced to beta features. They may still be available, but a special command may be required to access them. These features are still lunder development, but still may be useful for some Cubit users if used with caution.
  • Multi-sweep: The many-to-many sweeping option must now be enabled by using the following command: set multisweep {on|OFF}.
  • Mesh based geometry Create/Modify commands: Operations such as imprint, webcut, intersect, unite as well as primitive creation operations for mesh based geometry are still considered beta. Use set facet_modify {on|OFF} to turn these features on and off
  • Triangle Coarsening: The ability to coarsen a surface mesh containing triangle elements has now been moved to alpha.

Defects Fixed in CUBIT 10.1

The following items are the user-reported bugs fixed since last release of CUBIT (May 2005). For more information contact Kevin Pendley(kpendle@sandia.gov)

Known Defects CUBIT 10.1

The following items are bugs or limitations that may be encountered in the current release of CUBIT. For more information on these defects contact Kevin Pendley(kpendle@sandia.gov)

Documentation Updates

CUBIT 10.1 How To

CUBIT 10.1 Contents of Release

Includes executables and libraries, packaged in tar.gz files for unix machines. For Windows, package is in a self-installing executable. UNIX, Windows, and Mac versions include full online documentation.

Platforms Supported

CUBIT 10.0 supports the following Platforms

• Linux (Compiled on RedHat Enterprise 4) 32- and 64-bit
• SGI Irix 6.5 32- and 64-bit
• Sun Solaris 8
• HP-UX 11.x
• Windows 2000, XP
• Mac OS X

CUBIT may be downloaded directly from the following URL: http://cubit.sandia.gov/release/. Contact Lydia Koch (lkkoch@sandia.gov) for a password to download the release.

Sandia Personnel: 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:

Contact Information

CUBIT Help

For general technical questions including download, installation and CUBIT technical assistance.

cubit-help@sandia.gov

CUBIT Licensing and Passwords

Aaron Carillo CUBIT Licensing Phone: 505-284-4118 Email: aacarri@sandia.gov

Lydia Koch Cubit Licensing Phone: 505-284-1783 Email: lkkoch@sandia.gov

CUBIT Support Lead

Kevin Pendley,
CUBIT Support Manager
Phone: 505-284-1957
Email: rakerr@sandia.gov

CUBIT Project Lead

Steven J. Owen
Sandia National Laboratories
Computational Modeling Sciences Department (org. 1421)
Phone: 505-284-6599
Email: sjowen@sandia.gov