General Mechanical

General Mechanical

Fatigue Analysis

    • aniis
      Subscriber

      Hello,


      I am doing a test for four point bending. I am using fatigue tool but I am not able to or I cannot predict the behavior after 100 cycles at some time or frequency.


      How can I provide this input for fatigue testing ?


      Thanks,

    • Keyur Kanade
      Ansys Employee

      Please post the questions in appropriate category. Moving this question to other category to get better response. 


      Moving to structural mechanics


       

    • peteroznewman
      Subscriber

      100 cycles is a very small number for fatigue. Is the maximum stress in the model above or below the yield strength?


      The Fatigue Tool in the Solution branch of a linear elastic model can use a material with Strain-Life data to predict low cycle fatigue.  You insert a Life result into the tool to see how many cycles of the applied stress it will take to cause a fatigue failure, and where in the model that is, which is obviously at the same location as the maximum stress.


      So you don't input the number of cycles, you just input the maximum load of a single cycle, and set the Fatigue tool up with the correct Loading Type, then get Life as an output.

    • aniis
      Subscriber

      Thanks Peteroznewman,


      The maximum stress is below the yield strength and yes, the stress and fatigue failure are at same point.


      Still my concerns is there any way or tool to know the properties of model at certain cycles of load and as well as at some frequency?


       


       

    • peteroznewman
      Subscriber

      Once you have found the minimum Life, say that is 50,000 cycles, then after 1,000 cycles you have used 2% of the Life.  After you have accumulated 25,000 cycles, you have used 50% of the Life.


      If you insert a Damage result, then you can enter the Exposure in seconds and it will do the division for you.

    • aniis
      Subscriber

      Thanks Peteroznewman, I get the concept now.

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