CUBIT™ 16.10 Release Notes

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.

New Features in CUBIT™ 16.10

Index of New Features

Meshing

Geometry

Graphical User Interface

Miscellaneous

Meshing

Robustness and speed improvements to node equivalencing

Equivalencing nodes now avoids potentially collapsing elements if 2 nodes within an element are within tolerance. Additionally, performance of equivalencing nodes is greatly improved for larger meshes.

Element area and length metrics now correct for all higher-order elements

The element area and length quality metrics for 2D and 1D elements respectively did not previously consider the higher order nodes in the computation, as if the elements were linear. This has been corrected so that they are now considered.

New expanded Sculpt command

The Sculpt command line in Cubit has been significantly enhanced to further support Sculpt’s extensive capabilities. Sculpt is a powerful external application for generating all-hex meshes in parallel, and can be run either standalone from a terminal window or through Cubit, taking advantage of Cubit’s powerful geometry tools and visualization capabilities.

The expanded Sculpt command line now supports the same syntax used in the sculpt input file. The command is still backwards compatible, but the expansion enhances its capability to support a wider range of options in Sculpt.

The new sculpt command is fully supported in the Cubit command panels providing full interactive support for most options in Sculpt, making it easier for users to set up and execute Sculpt commands within the Cubit environment.

For more information see: Sculpt Command Reference

Scaling options in Sculpt

Sculpt has added a new feature to allow scaling of geometry in different directions. The old scale option has been deprecated and replaced with xscale, yscale and zscale options. The ability to specify different scale factors in x, y, and z directions is now available. If you wish to use the previous constant scale behavior, set xscale, yscale and zscale to the same value.

For more information see: Sculpt Mesh Transformations

Compressing material IDs from SPN files in Sculpt

A new feature has been added to Sculpt, which changes the default behavior of material IDs in the resulting mesh file. Instead of compressing the material IDs found in the spn file, the actual material IDs will now be used for block IDs in the resulting mesh file. If the previous behavior is desired, the user can include the option "compress_spn_ids=true".

For more information see: Sculpt Input

Improved handling of Stitch format in Sculpt

The input_stitch option in Sculpt now automatically extracts the intervals from the stitch file when reading it. The previously required specification of the global Cartesian intervals is no longer necessary and will be ignored if provided with the input_stitch option. This change streamlines the input process and eliminates the need for manual specification of the intervals.

For more information see: Sculpt Input

Default processors in Sculpt command line

The default for the number of processors option in the Sculpt command has been changed. The new default is now set to the number of available processors, up to a maximum of 16, if the user does not specify a number. The previous default was set to 4 processors.

For more information see: Sculpt Process Control

Geometry

New reduce surface slot command

The reduce surface slot command is used to decompose slot surfaces in Electromagnetic (EM) modeling for easier application of boundary conditions. It also provides for additional options for preparing input for the external NGS Morph mesher.

reduce surface slot [hardware volume ] [radius ] [group ] [group_edges ][group_inner_edges ] [group_outer_edges ] [name ][name_edges ] [name_inner_edges ][name_outer_edges ] [make_free_curves] [preview]

The reduce surface slot command is enhanced with the addition of the geometry power tool’s slot surfaces diagnostic, which allows for identification of slot surfaces and fastener hardware through machine learning. The new reduce slot surface panel provides a convenient way to set up the command and visually preview the decomposition of slot surfaces using graphical representation.

For more information see: Reduce Slot

New blunt tangency command

A new blunt tangency command uses tweaking to increase a surface’s radius, increasing small angles at geometric tangencies. It is also equipped with a tolerance parameter parameter to prevent creation of sliver geometry.

blunt tangency tweak vertex [angle] [tolerance] [preview]

For more information see: Reduce Thin Volumes, Blunt Tangency

Image of blunt_tangency_tweak
Example of before and after blunt tangency tweak

Additional SGM support in Cubit

Support for the SGM geometry library in Cubit has been expanded:

  • Names can now be assigned, removed, and renamed for SGM geometry entities.
  • SGM geometry can be exported as either an SGM file or a STEP file.
  • The “Measure Between” command now supports measuring with SGM geometry entities.

This limited support enables a couple of useful workflows.

  1. Importing with SGM provides powerful geometry healing, after which the healed geometry can be exported to a STEP or SGM file for subsequent use in Cubit, Morph, or other programs. Names can optionally be assigned to SGM entities, and the names will be written to the STEP or SGM file.
  2. SGM geometry can be imported along with free mesh for visualization and to measure distances between mesh and geometry.

Fix for STEP import of multi-surface sheet bodies

Multi-surface sheet bodies are now imported from a STEP file as such, instead of each surface created as a single-surface sheet body.

Classification of surfaces using machine learning

The classify command has been updated to support both volumes and surfaces. To classify a surface, use a command such as classify surface '<surface_category>', which will generate training data and store it on disk with label ‘<surface_category>’. To predict the categorization, you would use classify surface <id>. The resulting classification prediction will be displayed in the output window, along with the confidence values for each category. The classify command also supports the with keyword when used with extended parsing, enabling the identification of surfaces with a specified category using a command such as draw surface all with category 'surface_category'

For more information see: ML Part Classification

Reinforcement learning for thin volume reduction

Cubit now introduces a new feature, Reduce Thin Volumes with Reinforcement Learning. The RL option simplifies a 3D thin volume into connected sheet bodies, similar to the Reduce Thin Volumes Auto. However, instead of relying on a set of pre-defined rules, the RL option uses machine learning techniques to make predictions based on a persistent knowledge base. With each iteration, the method builds training data and improves its choices for reduce operations.

The RL option generates a sequence of Cubit commands that can be exported to a journal file for the user to validate, edit and archive. The resulting sheet bodies are automatically associated with the original 3D geometry and have attributes necessary for shell finite element analysis.

The RL tool operates in two modes: Predict Mode and Learning Mode. In Predict Mode, the method predicts the reduction operations based on established training data. In Learning Mode, the method gathers information about the state space of the assembly to establish training data. The method will stop based on a stopping criteria, reaching the maximum number of iterations, finding no additional unique solutions, or user abort. The user can also influence the learning process by adding their own training data through the Thin Volumes diagnostic in the Cubit Geometry Power Tool.

For more information see: Reduce Thin Volumes with Reinforcement Learning

Graphical User Interface

Webcut solutions in meshing power tool

Introducing a new addition to the Meshing Power Tool – a solutions window that displays potential webcuts for the selected volume. With a similar layout to the Geometry Power Tool, you can preview the webcut, and with a right-click on the displayed solutions, access a menu option that brings up the relevant webcut command panel, pre-populated with the necessary parameters. To activate the solutions window, simply check the “Show Webcut Solutions” checkbox at the top of the Meshing Power Tool.

Image of meshing_power_tool
Meshing power tool shown with new solutions window

For more information see: Meshing Tools

New shell model management with the geometry power tool

Cubit’s Geometry Power Tool has been enhanced with the new Beam and Shell diagnostic, making it easier to simplify thin volume assemblies. This diagnostic streamlines the reduction of volumes to connected sheet bodies, which can then be meshed with triangles or quadrilaterals. When run with machine learning models loaded, the Analyze button produces two lists: Thin Volumes and Sheets. The Thin Volumes list offers custom reduction options, while the Sheets list displays defined sheet bodies with editable thickness, loft, and block attributes. The diagnostic also provides access to custom solutions for further customization and the option to export sheet data for analysis input deck setup. Additionally, quick access to automatic thin volume reduction tools, including reinforcement learning, is also available.

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(Left) Thin Volumes diagnostic showing volume with possible reduction solutions. (Right) Sheets diagnostic showing reduced volumes along with possible solutions for connecting adjacent sheets.
Image of shell_modeling
Example thin volume (left) and preview of two possible reduction solutions (right)

For more information see: Beams and Shells

Geometry power tool new classify surfaces diagnostic

A new diagnostic for surface classification has been added to the Geometry Power Tool. This diagnostic allows for classification of surfaces into custom categories, similar to the existing part classification feature. The classification is performed using machine learning models that can be loaded through the “Load ML Models” button in the Options panel. Upon analysis, each surface in the model will be assigned a predicted category.

For more information see: Machine Learning with Geometry Power Tool

Geometry power tool new slot surfaces diagnostic

The Slot Surfaces diagnostic is a new addition to the geometry power tool for preparing slot surfaces in Electromagnetic (EM) modeling. A slot surface is used to identify potential pathways where EM radiation can potentially exit. This diagnostic will help manage slot surfaces and prepare them for the application of boundary conditions and analysis. The diagnostic utilizes Machine Learning (ML) to predict the most likely slot surfaces. It also provides interactive tools for easily previewing and preparing slot surfaces for meshing using the external NGS Morph tool.

Image of slot_gui
(Left) Example slot surface showing preview of decomposition. (Center) Geometry Power Tool with Slot Surface Diagnostic showing slot surfaces identified with ML. (Right) Reduce Surface Slot command panel.

For more information see: Slot Surface Preparation, Reduce Slot Surface

New reduce thin volumes with reinforcement learning command panel

The new “Reduce Volume Thin RL” command panel is a valuable addition to the suite of reduce operations that utilizes the latest in machine learning technology. This panel offers full access to the training and prediction of thin volume models using the new command line option for reducing thin volumes. When used in conjunction with the “Beams and Shells” diagnostic from the geometry power tool, the relevant volumes are automatically populated in the command panel, making it easily accessible from a context menu.

Image of RL-command-panel
New Reinforcement Learning command panel

For more information see: Reduce Thin Volumes

New reduce surface slot command panel

The reduce surface slot command panel is a new addition to the suite of reduce operations that utilizes machine learning capabilities. When used in conjunction with the geometry power tool slot surfaces diagnostic, the slot decomposition process is made easier with the help of the new reduce surface slot panel. The panel provides options to input the hardware and radius information, automatically populating the necessary fields based on the slot geometry. Additionally, users have the ability to specify grouping and naming options for the decomposed slot surfaces.

For more information see: Reduce Slot Surface

New Sculpt command panels

Cubit introduces new command panels for setting up Sculpt input, providing better support for the full range of Sculpt capabilities. The panels are organized based on the structure of the Sculpt input options and provide a comprehensive set of options that were previously only available when running Sculpt external to Cubit.

The new panels can be accessed from the Meshing->Volume->Sculpt menu and cover the following categories:

  • Process Control: includes specifications for the number of processors, file names, and run options.
  • Overlay Grid: allows you to set up either a Cartesian overlay grid or specify an Exodus mesh as the overlay grid. It also supports Pamgen overlay grids.
  • Input Geometry: defines the geometry that will be used, with the default being the current geometry in Cubit. Alternative sources for geometry include external STL files, diatom files, volume fraction files, microstructure files, SPN files, or stitch files.
  • Mesh Options: control the type of mesh including stair-step, mesh void, hex dominant, periodic and degenerate hexes.
  • Smoothing Options: control options for smoothing curves and surfaces.
  • Mesh Improvement Options: includes options for pillowing, defeaturing, geometry capture, thickening, and removing bad quality elements.
  • Adaptivity Options: specify adaptive criteria, including the recent addition of adaptation based on material ID.
  • Boundary Conditions: choose from several methods for generating sidesets, defining material and sideset names, and adding new boundary conditions.
  • Output Options: set the output Exodus file name and define options for transformations, exporting various file types, and log output.

In addition, the Sculpt panel now includes a new Preview button that displays the contents of the Sculpt input file in the Cubit output window. This allows you to check the current structure of the commands and to copy and paste to a text file for running externally.

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New Sculpt command panels showing the nine different categories of options.

For more information see: Sculpt Commands

Miscellaneous

Python 3.6 through Python 3.11 now supported

Easier integration with user’s workflows, tools, and scripts is now enabled by supporting more than just Python 2.7 and 3.7. Cubit’s python modules can now be imported into any python environment of version 3.6 and newer. This is enabled by Cubit’s use of the Python Stable Application Binary Interface.

Element_count extended parsing now supports exodus entities

When using "element_count" in extended parsing, exodus entities are now supported. For example, the following command now works.
"list block with element_count > 2400"

Tet meshing errors now correct

The node ids generated when tetmeshing generated errors were previously incorrect. This has been corrected, allowing users to quickly locate areas in the triangle mesh that are preventing tetmeshing from succeeding.

CUBIT™’s Python Interface Enhancements

  • gaps_between_volumes – Returns a list of VolumeGap objects defining the gaps
  • is_surface_meshable – Returns whether a surface is meshable with the current scheme
  • get_entity_names – Returns all names of an entity

Defects Fixed in CUBIT™ 16.10

Ref#Description
MESH-817Re-enable testing with graphics on the linux build machine.
MESH-4173keep_lower_geometry not recognized – remove option from GUI.
MESH-5135Refine in Sculpt based on geometry id.
MESH-6669Python 3.9+ compatibility.
MESH-6670Running sculpt 16.04 on a mac.
MESH-6680Open Command Panel if closed and power tool links hit.
MESH-6682SGM STEP import/export in CUBIT.
MESH-6695Incorrect  journaled command.
MESH-6742Support multiple versions of python.
MESH-6749Investigate mesa issue on persistent DaaS machines.
MESH-6852Wrong node ids in tetmeshing error messages.
MESH-6877Rework genSlotModel with SGM and CUBIT.
MESH-6878Meshed surface area of tri6 incorrect.
MESH-6900Better handling of reversals in sweeping and interval matching.  Using mesh angle for vertex type.
MESH-6909Long delays after Cubit unloads.
MESH-6911Parse_cubit_list error.
MESH-6948Column width option.
MESH-6951Undocumented command – Remove Sliver Curve.
MESH-6962Cubit 16.08 bug in gui model tree.
MESH-6972Tetmesh issue during training.
MESH-6975Sculpt version in cmake list.
MESH-7097Sculpt parallel command when hitting preview input.
MESH-7105Bug projecting then imprinting curves onto composite surface.
MESH-7107Super vs. Superelement_topology.
MESH-7118Support for element_count to use element blocks, sidesets and nodesets.
MESH-7119Simple volume should be automatically sweepable.
MESH-7121Fix recent regression in create curve polyline with locations.
MESH-7134Improvements in sweeping quality.

Documentation Updates

The CUBIT™ 16.10 online documentation may be found here. A PDF version is 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™ 16.10 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.

Platforms Supported

CUBIT™ 16.10 supports the following Platforms:

  • Linux RedHat Enterprise 7 and 8
  • Windows 10
  • macOS 10.14+

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™ 16.10 may be downloaded from the CUBIT™ download page.

Sandia Personnel Only

CUBIT™ 16.10 may be downloaded from the CUBIT™ download page.

Windows

Download a Windows installation file and double-click to install.

MAC OS X

Download a Mac OS X disk image file. After the disk image is opened, click and drag the CUBIT™ folder to /Applications.

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>
cubitThe latest released version (16.10) of CUBIT™ deployed to the LAN.
cubit -noguiThe latest released version (16.10) with just the Command Line and graphics window
cubit -nogui -nographicsThe latest released version (16.10) with just the Command Line
cubit-16.10Version 16.10 with GUI
cubit-betaThe 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

Email: asc-approvals@sandia.gov

CUBIT™ Support Lead

Trevor Hensley
Phone: 505-284-7756
Email: cubit-help@sandia.gov

CUBIT™ Project Lead

Roshan Quadros
Sandia National Laboratories
Computational Simulation Infrastructure (org. 1543)
Phone: 505-220-9458
Email: wrquadr@sandia.gov