General Mechanical

General Mechanical

Signed von mises stress

    • ashish35
      Subscriber

      Hello,


      I couldn't find any option to view signed Von Mises stress result in Mechanical. Is it possible to view this result?


      Best,


      Ashish

    • Rohith Patchigolla
      Ansys Employee

      Hi Ashish, 


      Signed von Mises stress can be calculated using user-defined results.


      Hydrostatic stress is simply the average of the three normal stresses [(sx+sy+sz)/3 ], so dividing the hydrostatic stress by the absolute value of itself will give -1 for compression and +1 for tension [(sx+sy+sz)/abs(sx+sy+sz)]. 


      This stress sign can be directly multiplied by the unsigned von Mises stress to produce the signed von Mises stress. 


      Signed Von Mises = seqv*(sx+sy+sz)/abs(sx+sy+sz)


       


      But the method breaks down when the hydrostatic stress is zero. So, we add a small number to the equation as shown below.


      Please use the below expression in a user defined result to get the Signed Von Mises stress. 


      seqv*(sx+sy+sz+1e-6)/abs(sx+sy+sz+1e-6)


      Hope this helps.


      Best regards,


      Rohith


       

    • ashish35
      Subscriber

      Rohith,


      Thank you so much. This is spot on.


      Best,


      Ashish

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