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CAD Import Module

Import CAD Files into COMSOL Multiphysics® and Prepare Them for Analysis

The CAD Import Module add-on to the COMSOL Multiphysics® simulation software assists your modeling workflow in two ways. First, you can import third-party CAD software geometries of a variety of file formats, including the Parasolid® and ACIS® formats, standard formats like STEP and IGES, and native file formats of various CAD systems. Second, it helps you ensure that the imported geometry is ready for analysis with tools for repairing geometry that inherits errors upon transfer, defeaturing geometry that is overly detailed, and removing geometric entities that cause unnecessarily fine meshes.

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The gray CAD geometry of a gas turbine model.

Importing CAD Files

Most CAD software supports the export of Parasolid®, ACIS®, STEP, and IGES file formats, which can then be readily imported into COMSOL Multiphysics® with the CAD Import Module. In addition, you can import the native file formats of a number of CAD systems, such as SOLIDWORKS®, Inventor®, PTC Creo Parametric™, NX™, and AutoCAD®. The separate product File Import for CATIA® V5 provides support for importing the native file format for this system. When you have installed the CAD Import Module, all CAD models and files are automatically converted to a Parasolid® geometry using the Parasolid® geometry engine that is included with the module.

These geometries can subsequently be changed using COMSOL Multiphysics® and the CAD Import Module. In addition to fixing errors, you may want to make other changes to your geometry, such as creating a model domain around a CAD design for use in CFD, acoustics, or electromagnetics analysis. Most CAD models are geometries of the objects to be manufactured, and simulation may be used to model the phenomena around this object, such as the flow of air. When these changes have been made, the CAD Import Module can export them in the IGES, STEP, Parasolid®, or ACIS® file formats for import into other tools.

The 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.

A close up view of the Import node Settings window and a manifold exhaust CAD model.

Supported Formats for File Import and Export

Note that not all file formats are supported on all operating systems; for details, see the system requirements. The STL, PLY, 3MF surface mesh formats are supported by COMSOL Multiphysics® without add-on products.

File Format Extension Version Import Export
ACIS® .sat, .sab, .asat, .asab up to 2022 1.0 (import),
R4, R7, 2016 1.0 (export)
AutoCAD® .dwg 2.5–2023
AutoCAD® DXF™ .dxf 2.5–2023
IGES .igs, .iges up to 5.3
Inventor® assemblies .iam 11, 2008–2023
Inventor® parts .ipt 6–11, 2008–2023
NX™ .prt up to 2206
Parasolid® .x_t, .xmt_txt, .x_b, .xmt_bin up to 34.0
PTC Creo Parametric™ .prt, .asm 1.0–9.0
PTC Pro/ENGINEER® .prt, .asm 16 to Wildfire® 5.0
SOLIDWORKS® .sldprt, .sldasm 98–2022
STEP .step AP203, AP214, AP242 (import),
AP203 (export)
 

Repair a Geometry on Import

The goal of building the CAD model is to obtain a digital representation of the real product. This digital version contains the 3D geometry of the product together with the information needed for manufacturing it. While a 3D CAD geometry is usually true to the real object it represents, small and hardly noticeable anomalies can occur throughout the geometry. This may be due to numerical limitations in the computer's ability to represent complex shapes, limitations of some older CAD file format, human errors, or translation of the data between file formats. These small anomalies may result in, for example, faces that do not meet exactly at the edges or inconsistent face normals and edge directions. In turn, this may lead to problems with forming valid, watertight geometric objects when generating a mesh within COMSOL Multiphysics®. Therefore, geometry repair is always performed by default during the import process to get you started with your simulations.

In addition to the automatic repair that occurs on import, the CAD Import Module provides features that allow you to manually repair your CAD models after import. You can, for example, manually select faces and knit them together to form a solid using a specified tolerance to close gaps. Alternatively, you can automatically locate the edges of gaps and use these edges as input to generate a new face that covers the gap and forms a solid.

Defeature a Geometry for Analysis

Once the CAD model has been properly repaired, it may still be difficult to use in a simulation due to the complexities of the geometry and the number of small geometric features in the model. Unless they are removed from the geometry before meshing, these features may lead to an overly inflated number of mesh elements, and thereby require more computational resources than necessary.

While some features, such as fillets, grooves, threads, and holes, are required for an eventual manufacture, they may not be relevant to a particular type of simulation. The CAD Import Module has the tools to remove them and simplify the geometry. You can delete fillets and chamfers; fill holes; and delete groups of faces, replacing them with a uniform surface through filling or patching.

Other unwanted features may have resulted from the CAD modeling and import process itself, like small faces, sliver faces, spikes, and short edges, for instance. For these unintentional features, you can select their type in an interface and specify a tolerance value to identify and remove all occurrences of this geometric feature. Defeaturing can also be performed automatically as part of the import process, utilizing the same tolerances specified for repairing.

Closeup of a sliver in a CAD geometry repaired and the mesh is improved.
Closeup of a CAD geometry shown in a side-by-side comparison of with and without a groove and hole.
Closeup of a CAD geometry shown in a side-by-side comparison with and without fillets.
Close up of a CAD geometry shown in a side-by-side comparison with and without capped faces.
 

Perform Virtual Geometry Operations to Simplify Mesh

Performing virtual geometry operations is similar to the defeaturing process, except that the imported geometry remains unchanged. Instead of changing the geometry, the virtual geometry operations instruct the mesher to ignore certain features that either do not influence the simulation greatly or are not particularly relevant to the desired simulation. The meshing subsequently takes place on a virtual geometry. Such operations involve ignoring vertices, edges, and faces; forming composite edges and faces; collapsing edges and faces; and more.

There are two ways to employ virtual geometry operations. The faces, edges, and vertices to be ignored can be manually selected, but there is also an automatic Remove Details operation that recognizes and removes small features by using a sequence of virtual operations (which can then be edited as necessary).

These operations are included in the COMSOL Multiphysics® platform and are a great complement to the defeaturing tools of the CAD Import Module. This functionality is particularly useful when the features of the geometry cannot be easily removed through defeaturing or repair, or when the simulation requires you to keep the curvature of the geometry intact.

Interfacing Directly with CAD Software

If you are a CAE engineer who also uses CAD software, COMSOL provides several add-on products that connect COMSOL Multiphysics® to each of the major CAD software packages, using specialized LiveLink™ technology. The synchronization feature in the LiveLink™ products automatically updates the geometry in one program when changes are made in the other. With the LiveLink™ products, you avoid the import/export and reimporting of the entire CAD geometry when you want to make changes for further analysis.

The following products contain this functionality:

The SOLIDWORKS UI is shown in the background with a gray bracket model geometry and the COMSOL Multiphysics UI is shown in the foreground with the optimized bracket model in the Graphics window and the stress visualized in rainbow.

Every business and every simulation need is different.

In order to fully evaluate whether or not the COMSOL Multiphysics® software will meet your requirements, you need to contact us. By talking to one of our sales representatives, you will get personalized recommendations and fully documented examples to help you get the most out of your evaluation and guide you to choose the best license option to suit your needs.

Just click on the "Contact COMSOL" button, fill in your contact details and any specific comments or questions, and submit. You will receive a response from a sales representative within one business day.

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