*AutoCAD DXF/DWG files containing solids, regions or surfaces can be imported into Autodesk Simulation as CAD data when the option to Import as: 3-D Surface/Solid is selected from the Options button in the Open dialog. DXF/DWG files consisting primarily of lines should be imported with the Wireframe option.
The disadvantage of opening a model without having the CAD application installed on the same computer is that the CAD model and the FEA files do not remain associative. The loads, boundary conditions, material properties, and other setup parameters will need to be re-entered if the CAD model is changed and re-opened with Autodesk Simulation. (See for details on Associativity.)
Opening Autodesk Inventor and Autodesk Mechanical Desktop files in Autodesk Simulation when those applications are not installed on the same computer may update the original files to a newer version. For example, when an Inventor 2009 part is opened with Autodesk Simulation 2011, the original Inventor file is updated to Inventor 2011 standards. This may prevent the part from opening in the original CAD application. Likewise, Autodesk Simulation will not open an Inventor model created in a newer version of Inventor than the version of Autodesk Simulation. If Inventor is installed on the same computer, open the model with Inventor and transfer it to Autodesk Simulation.
Drag-and-drop technology is also supported, so you can simply drag the file onto the Autodesk Simulation icon on the Windows Desktop, or into an open Autodesk Simulation window, and the software will take care of the rest.
STEP files might be saved in a different unit of length than shown by the CAD software. (This functionality varies from CAD package to package.) Use the OpenOptions command to control whether the STEP file is converted to a different unit of length when the file is opened with Autodesk Simulation. (The Open Options command also includes an option about whether to prompt you for the units each time a STEP file is opened.) For example, the CAD model may be saved in units of centimeters from the CAD software even though the units in use were inches. If the model is not converted when opened with Autodesk Simulation, the units of length will be centimeters, and this would require all input that uses a length unit to use centimeters, such as moments (force*cm), modulus of elasticity (force/cm2), thermal conductivity (energy/(cm*time*degree)), and so on.
Scaling the STEP file from the original units to a new unit also scales any inaccuracies in the file. If the model is scaled by a large amount, such as from centimeters to microns (a factor of 1E4) or from meters to microns (a factor of 1E6), then problems may occur with feature matching and other tolerances which could prevent the model from meshing.