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Fatigue Analysis on shaft

Question asked by Elliott Tuthill on Jun 29, 2012
Latest reply on Jan 23, 2013 by Gopal Sharma

I have a shaft that is used in a pump.

The shaft has a belt attached to the top that transfers a torque to rotate the shaft. The torque applied is known and that value is 42,000 lbs-in. The shaft has two bearings that are located above and below the middle extrusion on the shaft. I am trying to do a fatigue anaylsis on the shaft however I don't think I am setting it up properly because it shows that damage and life seem to have no affect after 1000 runs.

screenshot 1.png

That is the shaft in order to replicate the two bearings I put a fixed hinge fixture in place of both bearings and a roller slider because I saw this done in a different question.


Now I put a torque where the belt is located and turned on use internal relief once again beacuse I saw it done in a previous question.


When I run it there is a warning "there is a significant external imbalance force in Z-direction which will be balanced by the application of opposing inertia forces. UNless your model is under such a force or under marginally imbalance foreces, application of Inertia Relief may alter the characteristics of your model."

This leads me to beleive i am doing something wrong but when I continue anyway it says excessive displacements were calculated in this model. If your system is properly restrained consider using the large displacement option to improve accuracy of the calculations. otherwise continue with current settings and review the causes of these displacements.

I click NO to solve with small displacement. I get this


This seems plausible but when I then run a fatigue study on this study I get this which doesnt make sense at all.


This leads me to believe that i have set up the static study wrong. I want to replicate a shaft that is held in place by two bearings and rotates around due to a pully attached at the top.


I have attached the solid works file as well