CUBIT 11.0 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 11.0

CUBIT 11.0, released November 2007, is a major advancement in geometry preparation and mesh generation technology. Although many new capabilities have been introduced, the new Immersive Topology Environment for Meshing (ITEM) is the highlight and focus of this release.

The Immersive Topology Environment for Meshing (ITEM)

ITEM introduces a dramatic new paradigm for preparing models for analysis. Aimed at simplifying and streamlining the model preparation for intermittent users of CUBIT, it provides a familiar wizard-like environment that works in harmony with existing CUBIT functionality. Stepping the user through the model preparation workflow, it can diagnose problems and present solutions to the user in a systematic fashion, starting with CAD import and model setup, through CAD cleanup, simplification, geometry decomposition and mesh quality assessment and export.

The user enters the ITEM environment by selecting the wizard hat icon on the power tools panel .The figure above illustrates a typical scenario where diagnostics can be performed and potential problems listed. For each problem, a set of solutions is presented, which can be selected, previewed and easily executed. Many new automated commands and tools have been introduced in CUBIT with ITEM. Complete documentation on How to use ITEM along with detailed technical documentation is included with this release.

Other new capabilities include the following:

Meshing	Geometry	Properties and Support
Improved Many-to-Many Sweeping Improved Auto-scheme Improved Hex Refinement pCAMAL: Parallel Meshing Support Improved Rebar Command New Focus Smoothing Options Mesh Quality Error Thresholds Mesh Error Management Meshed Volume Output Progress Bar and Interrupt for Mapped Meshing	Undo Capability for Geometry Operations Interoperable Virtual Geometry Remove Topology Command Geometry Preparation Diagnostics Automatic Geometry Cleanup Automated Geometry Decomposition Volume Overlap Visualization Tweak Commands on Sheet Bodies Additional Body Creation Options Additional Surface Creation Options Collapse Curve Improvements Additional Split Surface Options Additional Imprint Command Measurement Between Entities New Fire Ray Option Enhanced Granite (Pro/E) commands ACIS Upgrade (V17)	Metadata Export to Excel Format Property Editor Metadata Enhancements Go To Metadata Part New Metadata Tree Views Variable Distribution Factors for Sidesets Cohesive Elements Support for Abaqus Import and Fluent Export Additional Exodus Export Option Cubit Configuration File Geometry Decomposition Tutorials

Meshing

Improved Many-to-Many Sweeping

Improved Auto-scheme

The autoscheme algorithm is a unique capability in CUBIT that automatically analyzes geometry and determines an appropriate meshing scheme based on characteristics of the model. This capability has been improved in version 11.0 by expanding the number of volumes it can recognize as "sweepable". This release includes significant efforts in improving automatic detection of sweepable and nearly sweepable volumes. For volumes that fall into the "nearly sweepable" category, as part of the ITEM wizard, it can now provide a list of possible source/target surface suggestions to help guide the decomposition process.

Improved Hex Refinement

pCAMAL: Parallel Meshing Support

CUBIT 11.0 introduces a new application, pCAMAL, that is designed to run on parallel computing platforms. This new application incorporates the CUBIT sweeping kernel and can generate large hex meshes that could not otherwise fit on traditional serial processors. The standard CUBIT application can be used to prepare a set of many-to-one sweepable volumes. A new parallel sweeping option in CUBIT will generate only the boundary mesh. CUBIT can then export the boundary mesh to an Exodus format file that can be read by pCAMAL. pCAMAL can then utilize its parallel meshing capability to generate a full 3D hexahedral mesh. The introduction of pCAMAL is the first step in addressing the need to generate huge meshes of 100s of millions of elements.

Hexahedral mesh of a nuclear reactor core generated using the new parallel pCAMAL application

Improved Rebar Command

The rebar command is used to automatically add edges to an element block. This command now also accepts a list of nodes as inputs in addition to the other forms of the command.

New Focus Smoothing Options

Cubit previously only allowed ranges of hexes or tris to be smoothed. This capability has been expanded to allow focus smoothing on ranges of faces, edges, or triangles.

Mesh Quality Error Thresholds

Cubit prints error and warning messages to the screen when the default quality metrics produce elements beneath a certain threshold. It is now possible to change the quality threshold at which these error and warning messages get printed.

Mesh Error Management

Meshed Volume Output

The list volume mesh command will now also list the meshed volume of an entity. The meshed volume is also displayed in the property editor.

Progress Bar and Interrupt for Mapped Meshing

The progress bar at the bottom of the CUBIT Window has a red 'X' which allows you to halt stalled processes in the middle of execution. This capability has been extended to include mapping and submapping processes.

Back to New Features

Geometry

Undo Capability for Geometry Operations

The Undo capability has been improved in this release of Cubit. In previous versions of CUBIT, the undo operation was limited to saving and restoring a full database file to roll back to a previous operation. With CUBIT 11.0, a full undo capability has been implemented with most geometry operations supporting any number of undo commands. The Undo feature is also incorporated into the new ITEM environment. Clicking on the Undo button in ITEM after an operation will attempt to undo all executed commands from the previous button press (some of which may include several CUBIT commands). If a command is not able to be undone it will be reported in the command line interface.

Interoperable Virtual Geometry

CUBIT has a powerful virtual geometry engine that enables the user to change the topology of a CAD model by compositing, partitioning or collapsing entities without changing the underlying solid model. In Cubit 11.0, the restrictions on the order of operations for virtual and real commands were reduced to allow webcutting and imprint operations to be interoperable. This release of Cubit 11.0 further extends the interoperability of virtual and real operations. Cubit's virtual geometry capabilities are now even more flexible. The following operations are now compatibile with virtual geometry.

Remove Topology Command

Geometry Preparation Diagnostics

Introduced as part of the new ITEM environment, Cubit 11.0 includes significant new efforts in topology recognition and evaluation for the purpose of creating meshable volumes. Running the diagnostics provided in the Prepare Geometry Panel, shown at right, will give instant feedback on how close the model is to being ready for meshing along with what needs to be addressed before meshing. Using a browser-like interface, the user can step through the potential problems and deal with them in a systematic fashion. The main geometry issues that are dealt with in this environment include the following. Fix Invalid Topology - Geometry is analyzed for validity and automatic healing options are provided. Remove Small Features - Cubit can search for small features using a user-defined small edge length. Small features are listed with potential solutions for each option. Clicking on a solution will preview it in the graphics window Connect Volumes - Cubit 11.0 improves the ability for the user to manage imprint and merge tasks, increasing the ability to merge entities which failed in previous versions of Cubit. Build a Meshable Topology - Cubit 11.0 has many tools to help guide the user through the task of preparing a geometry for meshing by modifying blend surfaces, decomposing a volume, suggesting source and target pairs, and forcing a sweepable topology

Automatic Geometry Cleanup

Based upon the built-in geometric reasoning and logic the new ITEM environment has the ability to let CUBIT automatically make the decisions on what should be done to clean up the geometry. While ITEM has the capability to present a series of solutions for a given problem allowing the user to select an appropriate solution, for many cases it can automatically select a solution without any user intervention. In many of the ITEM panels, an auto button is included allowing a fast and efficient way to resolve problems in the model. The auto-clean features are also available from the CUBIT command-line. The new Automatic Clean commands allow you use real and virtual operations to automatically remove small curves and surfaces, split narrow regions, or force a sweepable topology on a volume.

Automated Geometry Decomposition

Those familiar with the pave and sweep approach to meshing understand the difficulty in recognizing sweep paths and performing appropriate webcuts to make the geometry sweepable. One of the most valuable additions to CUBIT, introduced as part of ITEM, is the ability to identify and display potential webcuts on a volume. Using sophisticated algorithms, Cubit will identify potential decomposition options for a given volume, and present these to the user in a selection list, with a graphical preview for each option. This tool will help guide users through the decomposition process, while the user still maintains great control over the outcome.

New Automated Geometry Decomposition Feature

Volume Overlap Visualization

Overlapping surfaces can be visualized using the new "Draw Overlap" command from the command line. Given two surfaces, the curves of each surface are drawn in wireframe, and the overlapping portion is shown in solid red. An optional "Add" keyword allows the user to visualize the overlap on top of the current display. This command was implemented primarily for use in the ITEM connect volumes panels but is also useful as a separate command-line tool when diagnosing problems with the imprint and merge operations.

Tweak Commands on Sheet Bodies

The following tweak commands are now available for sheet bodies. These options can be useful when working with models composed only of surfaces that will be meshed with shells.

• Tweak Surface Remove
• Tweak Curve Chamfer
• Tweak Curve Fillet

Additional Body Creation Options

A useful tool for creating a volume in CUBIT is the command Create Body from Surfaces, which takes a set of surfaces and forms a body from them. In CUBIT 11.0 the default for this command will now expect a closed or watertight set of surfaces. This provides additional error checking for the user since most 3D meshing tools in CUBIT require a watertight volume where there are no gaps between the surfaces. In order to create a body that does not represent a closed volume, such as those needed for shell modeling, the new sheet option should be used with this command.

Additional Surface Creation Options

Cubit 11.0 has added an option to create a surface by sweeping a curve to a target plane using the extended plane parsing syntax.

Collapse Curve Improvements

Cubit 11.0 provides an option to the collapse curve command to designate using a "real" split surface operation during the collapse curve command rather than using a virtual partition. A new optional keyword "real_split" has been added to the command syntax to distinguish between the two forms of the command. The "real_split" option has also been added to the GUI.

Additional Split Surface Options

The new Split Surface Extend command allows you to create a split surface by extending a linear hardline until it reaches a surface boundary.

Additional Imprint Commands

The capabilities of the imprinting and merging commands have been enhanced in this release of Cubit. The new Imprint with position command allows you to imprint a body or volume with coordinate positions.The last release of Cubit 10.2 introduced tolerant imprinting, which extended the capabilities of imprinting for models on which normal imprinting failed. Cubit 11.0 extends this capability to allow tolerant imprinting of surfaces with curves.

Measurement Between Entities

A new measurement command allows users to measure between all different geometry and mesh entity types. The minimum distance between any two points on the entities will be returned.

New Fire Ray Option

The New Fire Ray option is useful for finding a location or set of locations on entities by extending a ray from a starting point towards an object. The user selects a starting location and a vector direction, and enters a list of bodies to intersect. The intersections between the ray and the entities will be returned.

Enhanced Granite (Pro/E) commands

Limited forms of sweep webcutting are now permitted on Granite (Pro/E) models.

ACIS Upgrade (V17)

ACIS is the third party geometry kernel that serves as the basis for all geometric operations in CUBIT. CUBIT 11.0 includes an upgraded version of ACIS to version 17.2. This may have some effect on the resulting entity IDs that are generated as a result of geometric operations between version 10.2 and 11.0 of CUBIT. Although the ID changes are minimal, if old journal files fail to run because of ID changes, we recommend using the ID-Less journal file capability to upgrade your old journal files to be compatible with version 11.0.

Back to New Features

Properties and Support

Metadata Export to Excel Format

Geometry assembly and metadata information can now be exported in a format that can be opened in a spreadsheet application such as Microsoft Excel. The metadata is exported using the Export Part_List "<filename>" [OverWrite] command. This will export an XML file that can be imported into Microsoft Excel as an "XML List". When it is in spreadsheet format, the data can be sorted and filtered using part properties.

New Metadata Tree Views New metadata tree views include a flat list of parts sorted by name or description. To access this tree view, right click in the geometry tree, select Part Name List or Part Description List

Variable distribution factors for sidesets

Equation-controlled distribution factors were introduced for nodesets in CUBIT 10.2. CUBIT 11.0 now provides the capability to define distribution factors for sidesets.

Cohesive Elements

Cohesive elements are zero-volume quad elements that are defined as element blocks composed of edges in the Exodus export. These elements are useful in modeling conditions such as adhesives which binds two materials together. During the analysis process, these elements may increase in area (e.g. when the glue begins to pull away.) The new Flatquad element type is used to indicate the existence of a cohesive region when the element block has been defined. Currently only the 2D case is supported in Cubit. Future releases will incorporate a full 3D capability.

Support for Abaqus Import and Fluent Export

Cubit supports a wide variety of import and export formats from other solid modeling, mesh generation, or analysis engines. Cubit 11.0 expands these capabilities for the following software.

• Abaqus mesh import
• Fluent mesh export

Additional Exodus Export Options

Cubit now supports the export of block, nodeset, and sideset names in the Exodus output file.

Cubit Configuration File

In previous versions of Cubit, certain settings were saved to the computer's registry on Window's platforms. These settings are now saved to a Cubit configuration file instead. The configuration file will save personal settings and formats between each run of cubit. This avoids the computer security issues which may arise as a result of requiring editing of the system registry settings.

Geometry Decomposition Tutorials A new set of step-by-step tutorials is introduced in this release of CUBIT. The new tutorials focus on webcutting strategies for creating sweepable volumes. This includes tips on recognizing sweepable configurations, determining sweep paths, using virtual geometry, dealing with small angles and narrow regions, and various webcutting syntaxes.

Back to New Features

Limitations CUBIT 11.0

• As of CUBIT 11.0, the Sun Solaris and Silicon Graphics platforms will no longer be supported. Previous versions of Cubit for Sun and SGI will still be maintained and available for download on the CUBIT website.
• IGES and STEP import functionality is not currently available for the Linux 64-bit platform.
• The Granite Geometry Kernel is currently not supported on Mac OS. 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 document in the users manual for a description of differences between the CUBIT's supported options between Granite and ACIS.
• The Mac OS X port does not support the changing mouse cursors on pre-selection
  It is recommended that a 3-button mouse be used for the Mac OS X version since interactive transformation utilize all three buttons.

Defects Fixed in CUBIT 11.0

The following items are the user-reported bugs fixed since last release of CUBIT (October 2006). For more information contact Kevin Pendley (kpendle@sandia.gov)

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

Known Defects CUBIT 11.0

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 Kevin Pendley (kpendle@sandia.gov).

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

Documentation Updates

CUBIT 11.0 How To

CUBIT 11.0 Contents of Release

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

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

Platforms Supported

CUBIT 11.0 supports the following Platforms

• Linux RedHat 9.0 32- and 64-bit
• Windows 2000, XP
• Mac OS X

Non-Sandia Users

CUBIT is available to for government and academic use. For information on licensing CUBIT go to the follow URL: http://cubit.sandia.gov/licensing.html. For current CUBIT users, CUBIT 11.0 may be downloaded from the website at the following URL: http://cubit.sandia.gov/downloads.html. If you obtained a password since the release of CUBIT 10, your password should work for 11.0 also.

Sandia Personnel Only

Windows

Download a Windows installation file from the dropzone. Go to the following directory \\dropzone\public\cubit\Windows. Copy the file Cubit.WindowsGUI.11.0.exe to your windows hard drive. Double click on the file and follow the installation instructions.

MAC OSX

Download a Mac OSX disk image file from the dropzone. Go to the following directory \\dropzone\public\cubit\MAC_OS_X. Copy the file Cubit_GUI_11.0.dmg.gz to your mac harddrive. Use gunzip to unpack the disk image file.

UNIX/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:

Contact Information

CUBIT Help

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

cubit-help@sandia.gov

CUBIT Licensing and Passwords

Kristina McGlotten
Cubit Licensing
Phone: 505-284-9152
Email: ksmcglo@sandia.gov

CUBIT Support Lead

Kevin Pendley
CUBIT Support Lead
Phone: 505-284-1957
Email: kpendle@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