CAD Import Tab

Activate the command: Application Menu Options CAD Import tab, or Tools Options Application Options CAD Import tab.

The Loaded CAD and file translation plugins section will display all the available modules for loading CAD solid model geometry. If you select a plugin, you can press the About button for version information.

When some plugins are selected, the Options button will become available. Click the Options button to set the default values used when importing or opening the CAD file. Many of the options are shared by various plugins. The options are as follows:

• Import invisible surfaces: This option for IGES files will allow you to include surfaces that were hidden during the IGES file creation by activating this check box.
• Split surface on import: This option behaves identically to the Import options: Split surface on import described below.
• Length units: STEP files are often saved in a particular set of units which may be different than the model units shown in the CAD software. When a STEP file is opened in Autodesk Simulation, the CAD geometry will be scaled from the units of length stored in the STEP file to the units of length chosen in this drop-down. The option Automatically detect length units will determine what units of length are used in the STEP file and use those for the model. (Also see the page Opening Models: Opening CAD Files: Importing CAD Solid Models with CAD Application.)
• Override model tolerance: When selected, the user-specified tolerance will be used to determine if feature lines are coincident or separate items. If the tolerance is too small and features that should be coincident are detected as being separate feature, then unmatched feature warnings may occur. If the tolerance is too large and features that should be separate are detected as being coincident, then multimatched feature warnings may occur.
• Prompt for length units during import: STEP files are often saved in a particular set of units which may be different than the model units shown in the CAD software. Therefore, activating this option prompts to select what units should be used for the length whenever a STEP file is opened. If this option is not activated, the STEP file will automatically be converted to the units specified for the Length units input (see above).
• Seam processing tolerance: The user-specified tolerance will be used for CoCreate, IronCAD, Inovate, and SpaceClaim files to determine if feature lines are coincident or separate items. If the tolerance is too small and features that should be coincident are detected as being separate features, then unmatched feature warnings may occur. If the tolerance is too large and features that should be separate are detected as being coincident, then multimatched feature warnings may occur.
• Show select output folder dialog on export from Alibre Design: When an Alibre model is transferred to Autodesk Simulation, the folder where the analysis files are stored needs to be specified. When this option is activated, choose the destination folder each time. When not activated, the model will be automatically placed in the Working directory for exports folder.
• Use ____ model tolerance: When selected, use the tolerance embedded within the file for determining if features and endpoints are coincident or separate items. (The ____ is replaced with the type of file, such as ACIS or STEP.) See also Override model tolerance above.
• Use Shading color and Use Rendering color: Rhinoceros has the ability to color the model based on the shading color or the rendering color. When the model is transferred to Autodesk Simulation, the color used will be based on which of these options is selected.
• Import Work Points? Set the option to Yes or No, to include or exclude work points from your model import, respectively. You can also set the option to Ask each time you import a model.

The Initial CAD rendering options section will allow you to set defaults for rendering a CAD solid model. (The surface of a CAD model is approximated with a series of triangular elements. The more elements used, the more accurate the shading.) Having the option Faster rendering activated is acceptable for most models since it gives a good surface rendering with a minimum of computations.

The Global CAD Import Options button will allow you to specify what options are used when working with a CAD solid model.

• The Split surface on import: radio buttons controls when the surface splitting procedure is performed on CAD solid models. If splitting is performed, Autodesk Simulation reviews the geometry and attempts to match the areas where parts meet. This procedure benefits analyses involving contact and will also enable you to generate additional parts based on the existing CAD geometry. Choose between Yes to always split the surfaces, or No to never split the surfaces, or Ask each time to decide whether to split or not for each instance. If you do not initially split the model, but subsequently want it split, you need to re-import the model. See the page Opening Models: Opening CAD Files: Surface Splitting for details.
• The option If FEA material data is found in the CAD model, it will replace existing material data on those parts in the design scenario pertains to the associativity between the Autodesk Simulation model and the CAD model. Imagine that a CAD model with steel properties is transferred to Autodesk Simulation for a thermal analysis. If the CAD modeler does not have the thermal properties (and usually, the CAD modelers are interested in just the mechanical properties), then the material will be modified in Autodesk Simulation to add the thermal properties. Hence, the interface will show the material as Customer Defined. Now the question is this: what happens if the CAD model is revised and transferred to Autodesk Simulation? Should the customer defined material be overwritten with the material properties from the CAD model? Or should the Autodesk Simulation material properties be retained? The answer to these questions is determined by the options set here.
  • The option for newly imported CAD models will be used whenever a new Autodesk Simulation model is created by opening or transferring a CAD model.
  • The option for the current model will be used only with the model currently in Autodesk Simulation.
  • The three options for each of the above options are Yes, No and Ask each time. Yes will automatically replace the material properties in Autodesk Simulation with the properties from the CAD model. No will not replace the material properties in Autodesk Simulation. Ask each time prompts whether to replace the properties or not when the CAD model is opened or transferred to Autodesk Simulation. Existing models will always ask whether to replace the material properties the first time the model is updated if you do not set it ahead of time.
• The Automatically generate contact pairs option will control whether or not a list of all contacting surfaces in the CAD model (for example, Part A Surface X contacts Part B Surface Y) is generated when the model is opened. If a large number of surfaces need a contact type other than the default contact type, then activating this option may be beneficial in order to generate the list of contacting surfaces when the model is opened. You will then need to locate each contact pair in the list and change the contact type. For example, if one third of the surfaces will require bonded contact, another third will require free contact, and the remaining third will require surface contact, you could activate the automatic option before importing the model, set the default contact type as bonded, and redefine the other sets as free and surface contact, respectively. If a small number of contacting surfaces in your model require a different type of contact, then it may be advantageous to deactivate this option and generate the contact pairs manually. The advantages are saving time when opening the CAD model and having a shorter list of contacting surfaces to manage. See the page Meshing Overview:Creating Contact Pairs for details.

Tip: Many of the above options can also be accessed while opening a model using OpenOption within Autodesk Simulation.

Parent topic: Options Dialog Box