General Mechanical

General Mechanical

Fatigue tool – results display error

    • CPete

      Hi all, 

      I'm having some issues with the fatigue tool in Workbench/Mechanical. My S-N data covers a range up to 1e8 cycles, and in the Mechanical Options I have defined a design life of 1e8 cycles, and yet my Life results in the Fatigue Tool show a max of 1e32 cycles. 

      This is really unhelpful as the results graphic is solid blue and there is no definition around the 1e3-1e8 range I am interested in. Attempting to adjust the legend to display a range of 1e3-1e8 does not seem to help. 

      I've attached an image showing a couple of locations where the cycle count is lower than 1e8, yet appear solid blue. 
      I am using stress life with mean stress curves from test data and max principal as the stress component. 

      Can anyone help? It obviously makes visualisation of the results very difficult and I have to find cycle count manually with the probe tool. 



      PS - sorry I cannot upload anything showing geometry in detail as it is confidential. 

    • CPete


      Just some further details – this is on an analysis with 2 time steps:

      Step 1 applies a bolt tension to the beam elements shown in the image above.
      Step 2 applies a vertical acceleration to all bodies. 
      I am using the fatigue tool to assess Step 2.

      Other bodies are hidden in the image, as I am only assessing the body shown. 


    • jonl

      Hi! The default legend setting has very poor resolution, which is evident when the results spans orders of magnitude. If you right click the legend, you can check "High Fidelity". It should give a much better visualization.

    • CPete

      Thanks for the suggestion. I gave it a go and sadly everything is still solid blue!

      Interestingly, I had a play around yesterday and changed the material to one of the default materials, and that changed the legend to show 0-1e8 cycles, and the graphic displayed correctly. It seems there's something funny going on with this material model, but I can't find any cause. 

      I've no idea why it is showing 1e32 cycles maximum when I have set 1e8 as my limit in the material model and the program. 

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