Inventor Frame Analysis or Stress Analysis! – Some Pro’s and Con’s

With the release of Autodesk Inventor Simulation 2011 comes frame analysis in addition to stress analysis. So the question, for some maybe, is which one to use.  Well if a component or indeed an assembly comprises of a uniform cross-section along its entire length and the ratio of  length/cross-section is greater than 10 then use Frame Analysis. As this will produce similar stress, and deflection, results a lot faster when compared to Stress Analysis.

Here I will use a simple I-Beam to outline the Pro’s and Con’s of using either Frame and Stress Analysis. The I-Beam will be fixed at one end and a load of  1000 Newton applied at the other (Like a cantilever).

Stress Analysis - Below are the Stress and Displacement results obtained from Stress Analysis

Pro’s -

  1. Can use non-content centre components
  2. Beams do not have to be modelled using Frame-Generator

Con’s -

  1. Number of Elements required can be very excessive to get reasonable results
  2. Stress Singularities in the component
  3. Longer Analysis times – related to point 1 (Con’s)
  4. Impractical (or impossible) to analyze assemblies with large number of beams – unless you have access to Super computers.

Frame Analysis - Below are the Stress and Displacement results obtained from Frame Analysis for the same beam

Pro’s -

  1. No Stress Singularities in the component
  2. A lot quicker to analyze than using solid elements
  3. Now possible to analyze large structures, consisting of uniform cross-section structures/frames

Con’s -

  1. Frames/Structures have to be modelled using content centre components or
  2. Frames/Structures have to be generated using Frame-Generator
  3. Cannot analyze localized connections (Bolts/Welds etc but can be achieved using both Frame & Stress Analysis)

RESULTS:

The displacement results from both analyzes are almost identical within 2% margin – well below th 10% default setting. Again the stress results in this case are within 8% although acceptable for comparison purposes-the main difference here is due to stress singularities, in the stress analysis, resulting from applying boundary conditions.

Hope you found this useful. There are more tips and guidance on Stress and Frame Analysis-including solving actual design problems in my new Inventor 2011 Simulation book.

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  1. #1 by Dan on May 12, 2011 - 6:26 pm

    It is good to see the “Frame analysis” included in Inventor.

    Is it possible to do “Truss analysis” with the “Frame analysis”? (Pin-joints 2-force members)

    I tried using “Beam Release”, but still getting some “Bending stress” on frame members.

    Thank you.

    • #2 by Wasim on June 11, 2011 - 9:33 pm

      Yes use pin connections on either end of beam

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