1 New In Coreform Cubit
1.1.4.4 Enhanced ability to obtain mesh in blocks, sidesets, and nodesets |
1.1 Release Notes: Coreform Cubit 2022.11
Coreform Cubit 2022.11 features a number of enhancements to core workflows, including meshing, geometry modification, and import/export. Additionally, numerous customer-reported bugs were fixed. Coreform Cubit 2022.11 is compatible with Sandia Cubit 16.06.
1.1.1 Support for Python 2 has been deprecated
Python 2 was sunset on Jan 1, 2020 and does not even receive security bug-fixes. While Python 2 scripts will still work in Coreform Cubit 2022.11, they are no longer officially supported.
Please note: Support for Python 2 will be completely removed from Coreform Cubit by no later than January 2023. Users still using Python 2 are encouraged to update to Python 3 as soon as possible.
1.1.2 Updates to the build uspline command
The build uspline command no longer supports building mutiple U-splines of different dimensions in the same command. For example,
build uspline surface 1 volume 1 as 1 2
is no longer supported, and users should instead run
build uspline surface 1 as 1
build uspline volume 1 as 2
1.1.3 Graphical User Interface
1.1.3.1 Model tree performance
The GUI model tree has been refactored to improve performance. The new tree is two times faster than the old tree for most change events. It is ten times faster for block, sideset, and nodeset id changes.
1.1.3.2 Increased control of Command panel layout
When using the standard navigation mode in the command panel, the number of buttons per row can now be changed from an Options/Preferences setting. Increasing the number of buttons per row can allow more space for complex command panels where limited vertical space is available.
1.1.4 Meshing
1.1.4.1 Superelement support
Coreform Cubit now allows importing element blocks of type ‘superelement’ from an exodus file. Visualization, picking, and listing of superelement blocks is supported. When visualizing superelements, they appear as a collection of nodes. Coreform Cubit GUI also supports them as shown in the image below. Coreform Cubit can also export superelement blocks, writing the data just as it was imported.
1.1.4.2 Improvements to Exodus sizing
Exodus sizing now has higher accuracy when computing a size from a location. It also has better performance by using an element based search tree.
1.1.4.3 Select blocks by element type
Element blocks can now be specified by element type using the command below. The type needs to be in quotes. Using ‘hex’ will get higher order hex types: ‘hex8’, ‘hex20’, etc.
Block with type <element_type>
1.1.4.4 Enhanced ability to obtain mesh in blocks, sidesets, and nodesets
Mesh in blocks can be specified directly now, instead of needing to identify the geometry in the block. For example, if a block contains a volume, to get the hexes it used to be necessary to type hex in volume in block 1. Now Coreform Cubit can get the hexes with hex in block 1.
Node|Edge|Element|Face|Tri|Hex|Tet|Wedge|Pyramid in Block|Sideset|Nodeset <ids>
1.1.4.5 New option in collapse tet command
The collapse tet command has a new option [Interior]. It forces the collapse to happen on the interior of the volume, instead of on the exterior tets. It prevents the collapse command from modifying surface triangles.
1.1.4.6 Syntax changes for set node constraint command
The syntax for the set node constraint command has been slightly modified to prevent user error. The options quality and threshold, which are only relevant to the smart option can now only be set when specify the smart option.
Set Node Constraint [on|off|smart [tet quality NORMALIZED INRADIUS|distortion] [threshold <threshold=0.3>]]
1.1.4.7 Tetmesh Default
MeshGems MG-Tetra_hpc (high performance computing) is now the default tetmesher in Coreform Cubit. (Instead of the serial MG-Tetra) Meshgems has been putting the bulk of their resources, development, and enhancements into this product rather than the serial version. With hpc, users can expect to generate higher quality tet meshes and better adherence to prescribed sizes. The command to change tetmesher back to the serial version would be to turn hpc off:
[set] tetmesher hpc ON|off [threads <value=4>]
1.1.4.8 Triangle remeshing
The ability to remesh a group of triangles has been added with the command:
remesh tri <id_range> | [quality <tri_metric> [less than|greater than] <value> ...] [inflate <value>][preview]
Remesh commands are a convenient tool to bypass the mesh deletion process and can replace a localized set of deformed elements after analysis. Similar to the remesh tet command, the new remesh tri command generates a new triangle mesh after deleting the existing mesh described by the input list of triangles.
1.1.4.9 Composite surface meshing
The trimesh scheme has been modified to better handle composite surfaces. If a composite surface has underlying geometric surface definitions, the actual surface definitions will be used by MeshGems hyperpatch meshing capability, allowing hidden curves of the composite to be ignored by the mesh.
1.1.4.10 Duplicate corner triangles
The triadvance meshing scheme has been enhanced to prohibit the creation of coplanar and nearly coplanar triangle creation at sharp, knife-edge corners of surfaces. If a vertex contains two triangles sharing three nodes, or two triangles that are nearly coplanar, a simple check is done at the end of meshing to see if swapping an edge of one of the triangles will eliminate this condition, creating volume at the tip.
1.1.4.11 Minimum edge length
A new command was added to set the minimum edge length for tet-meshing. Setting the minimum edge length prevents other sizing parameters, such as curvature, from producing mesh edges that are too small. However, smaller mesh edges will still be produced if there are any geometry edges smaller than the given size.
[set] tetmesher HPC minimum edge length [<value>]
1.1.4.12 Sizing on discrete curves
Mesh sizing on curves of a discrete surface are now respected during triangle meshing.
1.1.4.13 Clean discrete mesh command
An option was added to clean the discrete geometry prior to tri-meshing. This step remeshes the underlying triangles of the discrete geometry surface to improve the representation prior to meshing with user defined sizes. This is useful if the underlying facets representing the discrete surface are not an optimal representation of the surface.
[set] trimesher clean discrete mesh on|OFF
1.1.4.14 Sculpt enhancements
Two new adapt_type options have been added: resample and material. With the resample option, the input volume fraction data from microstructure file formats (input_micro, input_cart_exo and input_spn) is down sampled, averaging volume fraction data across multiple cells according to the adapt_levels set. With the material option, refinement is done in cells where the predominant volume fraction is a user specified material ID. To specify that material ID, use the new "adapt_material" option. Multiple materials can be used along with an expasion distance where the material adaptivity will occur.
A new "geometry_and_blocks" option has been added to "input_mesh_material". with this option, the block IDs in the final mesh come from the input genesis blocks and materials from the diatom/STL file.
Two new options have been added to use with the free_surface_sideset option. The first is the new sheet wear method. This option wears a swept input mesh in layers. The second is the crack_min_element_thickness, which is used with the sheet wear method. It defines the minimum allowed thickness of the elements resolving the side of a crack.
The new input_stitch file format allows Sculpt to read a stitch file. Stitch is a new I/O system that has been added to Sandia’s SPPARKS (Stochastic Parallel PARticle Kinetic Simulator) tool. See dump stitch and set stitch for more details. See also options stitch_timestep, stitch_timestep_id, stitch_field, and stitch_info that support the new input_stitch capability.
1.1.4.15 Paving with small features
The paving scheme is more robust in cases where mesh size approaches feature size, especially at holes. Improvements have corrected the algorithm from meshing over small holes. Increased element quality is also another benefit.
1.1.5 Geometry
1.1.5.1 Webcut with offset surfaces
A new webcut operation has been added that allows a volume to be cut with surfaces offset from its bounding surfaces. This new feature can be used to separate the mesh of the volume boundary.
1.1.5.2 Specify surfaces by normal
Surfaces can now be specified by a normal at the surface’s center point with the command below. The tolerance is the maximum distance between the tips of the two normalized vectors: user input vector and actual surface’s normal.
Surface with normal <x> <y> <z> [tolerance <value>]
1.1.5.3 Specify surfaces by location with tolerance
A tolerance option has been added to specifying surfaces at a location. Surfaces with a centroid within tolerance to the input location will be selected.
Surface at <x> <y> <z> [tolerance <value>]
1.1.5.4 STEP export now writes out names
If users have assigned names to geometry entities in Coreform Cubit, those names will be written into a STEP file upon export. Similarly, upon STEP import those names will be assigned to the entities.
1.1.5.5 Restricted stitch command
A ‘restricted’ parameter has been added to the stitch command. It allows stitching to operate in ‘restricted’ mode, where only the boundary edges of the sheet bodies or volumes participate in the stitch operation. This improves performance for large models.
stitch body|volume <ids> [tolerance <value>] [no_simplify] [no_tighten_gaps] [restricted]
1.1.5.6 Regularize command keep option
The regularize command now has a keep option that allows the specified curves and vertices to survive the operation.
regularize body|group|volume|surface|curve|vertex <ids> [keep curve|vertex <ids>]
1.1.5.7 Imprint with tolerance
A new optional tolerance parameter has been added to the volume/vertex imprint command.
imprint volume|body <range> [with] vertex <range> [keep] [tolerance <value>]
1.1.5.8 Include parsing
New options can now be used with the include parsing keyword: similar, cavity, hole, blend_chain, chamfer_chain, continuous, and nearby. The parser compares the specified entities and includes additional entities that match the criteria. For example:
draw volume 1 include nearby select surface 10 include hole remove surface 20 include blend_chain
1.1.6 Miscellaneous
1.1.6.1 Draw remove command
Coreform Cubit has had the ability to draw a portion of the model with the draw command. Geometric entities could be added to the portion that was drawn. Now geometric entities can be removed from the partially drawn model. This simplifies the commands when displaying only a portion of the model. The new draw remove command will not hide a part of the model in normal display mode. It only works when drawing a portion of the model.
1.1.6.2 Pyramid element support
The Abaqus exporter will now export pyramid elements. The Nastran importer will now read in pyramid elements.
1.1.6.3 OpenFOAM boundary patches
The output of boundary patches for OpenFOAM export has been fixed. It will now write out the patches with the user assigned names. The wall boundary condition type is now used by the OpenFOAM exporter as well.
1.1.6.4 Lite mode improvements
When importing a mesh in lite mode, parsing now supports finding elements attached to nodes. For example, the following now works.
draw hex in node X
1.1.6.5 New GDF exporter
A new export command has been added to support the GDF (Geographic Data Files) format. The command syntax is:
export gdf <filename> <entity_list>|block <range> [ulen <value=1.0>] [gravity <value=9.80665>] [isx <value=0> ] [isy <value=0>] [overwrite]
1.1.6.6 New OBJ importer
Coreform Cubit is now able to import OBJ files that contain tessellation of polygonal faces.
import obj <filename> [feature_angle <value>] [surface_feature_angle <value>] [make_elements]
1.1.6.7 Importing with block names
The import mesh and import mesh geometry commands have a new block_name option. This option allows the user to import only the mesh from the named blocks.
1.1.7 New CubitInterface functions
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1.1.8 Defects Fixed in Coreform Cubit 2022.11
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1.2 Release Notes: Coreform Cubit 2022.4
1.2.1 U-splines
Coreform Cubit now supports U-spline construction on volumes meshed with the following mesh schemes:
Map
SubMap
Sweep
Sphere
Polyhedron
TetPrimitive
1.2.2 Graphical User Interface
1.2.2.1 Selection by entity name in graphics window
The right click menu now provides an option to select entities that share the same name. It will select entities that have the same prefix up to the "@" character.
1.2.2.2 Select Chamfer Chain
When selecting a chamfer surface, the ‘select chamfer chain’ option is available in the right-click context menu.
1.2.3 Meshing
1.2.3.1 New Mass Increase Ratio metric added to Cubit
The Mass Increase Ratio metric is based on the timestep metric and can be used as a guide to determine how much an element’s mass can be scaled during analysis, to typically increase timestep. Users specify a minimum ‘target timestep’ and then use this metric to see how much an element’s mass will be scaled by to meet the specified timestep. Available for use on tets and hexes.
1.2.3.2 Geometry-Aware Spider Blocks
When creating spider blocks with the command:
Block <id> Joint [Vertex <id> | Node <id>] Spider {Surface|Curve|Vertex|Face|Tri|Node} <range> [preview][Element Type{ bar | bar2 | bar3 | BEAM | beam2 | beam3 | truss | truss2 | truss3 }]
and geometry (surface|curve|vertex) is referenced, the spider block is linked to that geometry, allowing the spider to update/regenerate the BAR elements if the mesh on the geometry is delete, remeshed, or translated.
1.2.4 Geometry
1.2.4.1 ACIS kernel updated to Version 2021.1.0.1
The ACIS geometry kernel has been updated to Version 2021.1.0.1.
use idless journal files, or
use the Python API to create idless Python scripts.
1.2.5 Sculpt
1.2.5.1 New Sculpt options
stitch_parallel option combines parallel files when no Nemesis data is included
match_sidesets_nodeset to more precisely define boundary between sides when using ‘match_sidesets’ option.
material_name, sideset_name, and nodeset_name added to define names on materials, sidesets, and nodesets respectively.
sideset and nodeset to allow for user-defined sidesets and nodesets based on xyz bounding box boundaries.
large_exodus to generate output Exodus file(s) to allow IDs greater than 2^31 (2.14 Billion).
input_mesh option under the gen_sidesets option. Used with the input_mesh option where an exodus file is used as the base grid. Only sidesets and nodesets defined in the input exodus mesh are transferred to the output mesh.
1.2.6 Graphics, Utilities, etc.
1.2.6.1 Enhancements to Free Entity Selection
The ability to select free surfaces (sheet bodies) has been added to the command:
Select Free [surface <id_list>] [curve <id_list>] [vertex <id_list>] [add|remove]
1.2.6.2 Added support for Corvid Velodyne files
Cubit now supports exporting files for use in Corvid Velodyne, via the command:
export velodyne ’<filename>’ [overwrite]
1.2.6.3 New CubitInterface functions
CubitInterface is Cubit’s python module that provides extensive capability for querying and modifying data in Cubit. The following functions were added to CubitInterface for version 2022.4.
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1.2.7 Defects Fixed in Coreform Cubit 2022.4
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1.2.8 Enhancements in Coreform Cubit 2022.4
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1.3 Release Notes: Coreform Cubit 2021.11
1.3.1 Usplines
U-splines are a revolutionary new spline technology, developed by Coreform, and can be thought of as a generalization of B-splines, NURBS, and T-splines. A U-spline is created by first generating a linear mesh to define the spline’s topology, then prescribing the polynomial degrees of the elements and degree of smoothness with their neighboring elements, and then computing the resulting U-spline in Coreform Cubit. The generated U-spline can then be used as a watertight CAD geometry definition or as an accurate and computationally efficient mesh for a simulation, a technique known as Isogeometric Analysis (IGA).
1.3.2 Usplines: Initial support in ANSYS LS-Dyna
Bézier Extraction is an IGA/spline technology that transforms a spline into a traditional "element point of view" format that can be more readily implemented in traditional finite element codes. ANSYS LS-Dyna supports Bézier extraction via DYNA’s *IGA_INCLUDE_BEZIER keyword and the "BEXT" files that Coreform Cubit can export from a U-spline.
1.3.3 Geometry Compliant Lattice Structures
Geometry Compliant Lattice Structures (GCLS) is a novel lattice construction technology that enables the efficient design of lattices that conform to a CAD model’s shape and size. GCLS structures are built using a background U-spline mesh, which the user generates on a CAD volume of the lattice region. Several default lattice unit cells are provided, as is a workflow for designing custom unit cells. This new feature is available as a separate license, Coreform Lattice GC™ . Contact sales@coreform.com for a free trial or other inquiries.
1.3.4 Updates to Coreform Cubit Learn licensing
We at Coreform are committed to ensuring that students, hobbyists, and open-source simulation developers have access to the world-class mesh generation capabilities in Coreform Cubit. In the 2020.2 release we accomplished this by releasing the Learn license for Coreform Cubit. Beginning with Coreform Cubit 2021.11, we have streamlined the licensing process for Coreform Cubit Learn. Going forward, all Cubit Learn licenses will require internet access and an account at www.coreform.com to be activated. All legacy Coreform Cubit Learn licenses that used the RLM server will expire 60 days following the release of Coreform Cubit 2021.11 (approximately January 2022).
- Get the new Coreform Cubit Learn license
Login to your Coreform account
Go to “Request Free Coreform Cubit Learn License” page
Click “Get Coreform Cubit Learn” button
- Download the latest version of Coreform Cubit
Go to Coreform Cubit Downloads page
Download the most recent release of Coreform Cubit for your platform
- Activate new Coreform Cubit Learn license
Launch latest version of Coreform Cubit
In the activation window that appears, select “Educational” and enter the email and password associated with your Coreform account
1.3.5 Changing tool for generating documentation
For many years Cubit’s help has been generated using RoboHelp. We’re transferring to using Scribble as our documentation tool, which is based on the Racket programming language. This transfer of documentation tooling, while still in its infancy, is now "live" and this manual is rendered using this new tooling. We expect there to be some rough edges, so if you find any issues with the documentation please send us a bug report at support@coreform.com!
1.3.6 Geometry tools: Taper surfaces
Exposed ACIS "taper" operation that tapers an array of faces about an array of corresponding edges and a supplied draft direction by a given draft angle.
1.3.7 Geometry tools: Create tangent curve
Added a new curve construction method that creates a spline curve that connects two points with prescribed tangent direction at each point. This can be particularly useful for smoothly connecting two discontinuous curves.
1.3.8 Mesh export: ’mesh-only’ export for ANSYS LS-Dyna
A new option has been added to the LS-DYNA .k mesh export utility to enable only writing the mesh data, which can then be *INCLUDE-d into another LS-DYNA .k file. Previously, this exporter would output a minimum working input file that included "dummy" keywords for items such as materials, steps, etc.
1.3.9 User experience: Improved performance importing complex assemblies
Improvements to file-reading algorithms have resulted in dramatically (>10x) faster performance when importing certain STEP files. For example the wall time required to read a large test file has been reduced from ~720 seconds to ~20 seconds, matching the performance of another, industry-leading, CAD software. The specific change is a refactor of the algorithm that checks for clashing entity names, turning an algorithm into an algorithm. This is not a breaking change.
1.3.10 New features in Coreform Cubit 2021.11
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1.3.11 Defects FIXED in Coreform Cubit 2021.11
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