Expand the CAD Functionality and Import CAD Files into COMSOL Multiphysics® with the Design Module

When running a simulation, you want to use the best geometric model for your particular analysis. The Design Module expands the CAD functionality of COMSOL Multiphysics® with additional tools for importing and revising existing CAD models, as well as sketching and building geometries from the ground up.

Whether you are removing irrelevant details from an existing geometry, recreating certain features of an imported CAD model, or constructing parametric geometries, the Design Module has features and functionality tailored for preparing a model for analysis.

Constraints and Dimensions

The Design Module includes a set of sketching tools used for adding constraints and dimensions to planar drawings for 2D models, 3D work planes, and in geometry parts. The constraint options include parallel, perpendicular, and tangent constraints. For example, to make two polygon segments meet at 90 degrees, you click on the two edges and use a perpendicular constraint. The options for dimensions include length dimension, radius, and angle. You can, for example, simply click and drag an edge to interactively set a length dimension. To aid in creating consistent drawings, the Design Module gives you immediate feedback, whether a sketch is underdefined, overdefined, or well defined.

Parametric Designs

All of the dimensions detailed above can be made parametric using the general parametric framework in COMSOL Multiphysics®. This enables you to run parametric sweeps across one, or multiple, dimensions. Additionally, when combined with the Optimization Module, you can run parametric optimizations, taking full advantage of the parametric functionality.

Fillet, Chamfer, Loft, Thicken, Midsurface, and Advanced Boolean Operations

The Design Module gives you access to standard CAD operations, such as fillet, chamfer, loft, thicken, and midsurface, as well as more advanced Boolean operations.

Fillet

Fillets are created by simply clicking on an edge and specifying a radius. This will create rounded corners on the selected set of edges and is used, for example, in structural mechanics to avoid stress concentrations and in electromagnetics to avoid electric breakdown.

Chamfer

Chamfers are created by simply clicking on an edge and specifying a distance. This will create beveled corners at the selected edges.

Loft

The Loft operation lets you specify a set of profile curves. The output of this operation is a loft surface, which consists of one or several faces that interpolate the profiles. This operation is used to create smooth geometric transitions between profile curves of different shapes.

Thicken

The Thicken operation is used to convert a surface object to a solid object by giving it a thickness, usually in the normal direction.

Midsurface

The Midsurface operation removes the thickness of a solid object having constant thickness, resulting in a surface object. Such surface objects are typically used with a Shell interface where the thickness is represented as a physics property instead of a geometric feature.

The Design Module provides more advanced Boolean operations that are expected to yield better results for more complex geometry models, for example, when computing the union of objects having touching faces that do not match exactly.

A sketch with parametric constraints and dimensions using the tools in the Design Module.
A fully parametric 3D model created using fillets and the constraints and dimensions tools.
Parametric optimization of fluid flow in a microvalve using parameters for the dimensions, available in the Design Module.

The Design Module supports the import of a wide range of common file formats, including the Parasolid® software, ACIS® software, STEP, and IGES formats. Moreover, you can import the native file formats of a number of CAD tools, such as the SOLIDWORKS® software, Inventor® software, AutoCAD® software, PTC® Creo® Parametric™ software, NX™ software, and CATIA® V5 software (requires a separate add-on product).

Imported CAD files are automatically converted to the format of the Parasolid® 3D geometric modeling engine within the Design Module. You can then modify and manipulate them using the Fillet, Chamfer, Loft, Thicken, and Midsurface operations, for example. Additionally, you can encapsulate geometries to model phenomena in the surrounding domains. After changes to a geometry have been made, you can export them in the Parasolid®, ACIS®, STEP, IGES, or STL file formats for import into other tools.

Repairing the Geometry Manually or Automatically

You can always perform geometry repair when importing a CAD design into the Design Module — even by default.

Geometry repair ensures the validity of the imported geometric information to avoid problems with meshing the geometry. Several types of problems are checked for and fixed during import, including tolerance issues that would prevent a perfect connection of geometric entities, self-intersecting entities, and very small edges and sliver faces.

The Design Module also contains tools to detect problems and repair selected CAD models to a specified tolerance. This way, you can adjust the tolerance to knit imported surfaces in order to generate a solid, or to remove small geometric entities, without the need to reimport the CAD file.

Defeaturing Models to Augment Better Meshing and Simulations

A sound geometry can still contain geometric features that make it difficult to mesh or perform an efficient simulation. In particular, small features may concentrate large numbers of mesh elements in regions where changes in the simulation results are negligible and can thus be ignored.

The Design Module contains tools for defeaturing by identifying and removing certain features, such as spikes, holes, slivers, short edges, and small faces, for example. Other defeaturing tools allow you to fill in grooves, cap faces, and remove fillets.

Using the Design Module, you can reintroduce deleted features, such as fillets and holes, and run a parametric sweep to study their influence on the simulation.

Virtual Operations Concentrate Simulations to Regions that Matter

Virtual geometry operations are a useful tool within COMSOL Multiphysics® that provides better meshing analysis solutions. This is done through instructing your meshing tool to ignore selected entities and features, thereby avoiding concentrating meshing in these regions — the meshing is taking place on a virtual geometry.

The ignored regions would typically be part of the geometry where your simulation results are uniform or irrelevant to your particular situation. You can use virtual geometry operations to ignore edges, vertices, and faces; subsequently form composite objects; or collapse the entities.

The automatic Remove Details operation analyzes the geometry and applies a sequence of virtual geometry operations in order to ignore undesirable features in the model.

These operations are included in COMSOL Multiphysics®, and complement the geometry manipulation capabilities of the Design Module, particularly when certain features are difficult or undesirable to remove through the Design Module repair and defeaturing tools.

The Design Module import functionality supports associative geometry import to retain physics and other settings on the geometry. Once a file has been imported, the software reads information in the CAD files to identify the geometric entities in the file. If and when the file is reimported due to a design change, all of the selections in COMSOL Multiphysics® will be updated and retained according to associativity rules, eliminating duplicate work. This information is usually available when importing CAD files saved in the native format of the software where it was created.

Supported Formats for File Import/Export

The following table lists the file formats included with the Design Module; for all supported file formats, see the file formats page. Note that not all file formats are supported on all operating systems; for details, see the system requirements.

File Format Extension Version Import Export
ACIS® .sat, .sab, .asat, .asab up to 2020 1.0 (import), R4, R7, 2016 1.0 (export) Yes Yes
AutoCAD® DXF™ .dxf 2.5-2021 Yes No
IGES .igs, .iges up to 5.3 Yes Yes
Inventor® assemblies .iam 11, 2008-2021 Yes No
Inventor® parts .ipt 6-11, 2008-2021 Yes No
NX™ .prt up to 1899 Yes No
Parasolid®

.xt, .xmttxt, .xb, .xmtbin

up to V33.0 Yes Yes
PTC® Creo® Parametric™ .prt, .asm 1.0-7.0 Yes No
PTC® Pro/ENGINEER® .prt, .asm 16 to Wildfire® 5.0 Yes No
SOLIDWORKS® .sldprt, .sldasm 98-2020 Yes No
STEP .step AP203, AP214 (import), AP203 (export) Yes Yes

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An electric motor assembly imported from a CAD file.
The Delete Holes defeaturing operation is used to find cylindrical holes.
The geometry resulting from using the Delete Holes operation.
The model geometry after all cylindrical holes have been removed via the Delete Holes operation.