Knowledgebase : Autodesk > Inventor

Inventor keeps loading after starting the application

By Karl Hosking - Support - A2K Technologies

We've seen a few cases recently where Inventor fails to load after start up, and the mouse cursor is blinking and loading non-stop.

The cause appears to be due to the installed Anti-virus software, which will need to be investigated by the System Administrator as the first step of troubleshooting.

More information on this problem here;


Once the AV has been checked, configured, disabled or uninstalled, and if the problem still persists, please reach out and we'll double check the system and find out what's going wrong.

HOW TO - Nastran in CAD

Based on reoccurring questions in Kayako: How to setup a fatigue analysis and where to get the material data from?


Static vs. Dynamic Fatigue

  • Static fatigue analysis explores the accumulation of damage in a part or assembly based on a single or sequence of stress states with a defined number of cycles for each. This can be accomplished outside of FEA for simple load scenarios
  • Finite Element based static fatigue in Autodesk Nastran In-CAD can factor in multi-axial effects of complex
  • However, when the load input is a PSD curve, static cases don’t exist, and a different approach is
  • Random Vibration Fatigue in Autodesk Nastran In-CAD can provide insight on this type of

Setup the Vibration Fatigue Analysis

20h vibration against gravity.

  1. Right click Analysis 1 and choose Edit
  2. Select the Vibration Fatigue analysis type
  3. Make sure Acceleration and Stress are turned on
  4. Click OK
  5. Double click Fatigue Setup 1 in the Model Tree
  6. Make sure the Stress Life approach and Maximum principal method are selected
  7. Enter 20 for the Event Duration
  8. Enter 3600 for the Time Conversion Factor (=3600 sec per hour)
  9. Click OK

Define the Fatigue Properties

  1. Right click Steel, Alloy in the Model Tree and select Edit
  2. Click the Fatigue button
  3. On the S-N tab, enter the following properties:
  4. B = 0.1
  5. Su = 72200
  6. No = 1000
  7. KF = 1
  8. Be = 0.001
  9. Se = 29000
  10. Click OK on both dialogs

For other material data, please refer to: for example. A pro-user member ship might be required. Another website is:

Define the Dynamic Setup for Example

  1. Right click Dynamic Setup 1 in the Model Tree and choose Edit
  2. Select the Vertical PSD curve
  3. Turn on the Frequency Range check box
  4. Specify 60 Hz as the Lowest Frequency and 1000 Hz as the Highest Frequency
  5. Enter 20 for the Number of Points in the Range
  6. Turn on the Spread around Modes check box and again specify a range from 60 to 1000 Hz spread over 10 points in the range
  7. Enter 5 for the Percentage Spread
  8. Click OK


Replace any existing Load with Gravity

  1. Add a standard gravity load in the Y direction (9.81 m/sec2 or 386.4 in/sec2)
  2. Click Run from the Ribbon to start the analysis


Review Fatigue Results

  1. Right click the Results in Model Tree and choose Edit
  2. Select RMS Output from the subcase list
  3. Select Fatigue and Shell Max Damage Bottom/Top from the Result Data menu

The Nastran results do not line up with the results from Inventor Professional. Is this a common issue or is this a Nastran bug?

Inventor Professional

Nastran in CAD


110.3 MPa

78.64 MPa



The reason is that the meshes have not bee converged. The initial meshes need to be converged manually by reducing the start size. The solving process converges the results automated relative to the mesh input. Once the change of the refined mesh results is less than 5%, the mesh can be assumed as converged.

Please refine the meshes through these menus:

Inventor Professional

Nastran in CAD

Mesh size in % of longest edge.

Mesh size in ‘mm’.

 The mesh is then refined by the solver based on the settings:

Inventor Professional

Nastran in CAD

Final Results Nastran in CAD: