General Mechanical

General Mechanical

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    • Adisa
      Subscriber

      Hi,


      I try to do bending beam in ansys and calculation by hand.



      After that the calculated stress is 70MPa.


      But in Ansys I did not get it.


      R18.2


      When the beam is without the radius, the difference is the bigger.


       

    • Rahul Kumbhar
      Ansys Employee

      From the image, the beam without radius R will have stress singularity in the corner. The stresses will be very high and unreal. Try increasing the radius, you may get closely matching result.

    • peteroznewman
      Subscriber

      Hi Adisa,


      You have made an error in geometry construction.



      If the inner radius is 1 mm and the thickness is 2 mm, then the outer radius must be 3 mm. You used 2 mm.



      You were also missing the 4 and 6 mm dimensions.



      You quote only one calculated stress, but there are two Sigma Y values, one on the left and one on the right,
      because the bending moment is +/- c but the Fy/A is only a compressive stress.



      Regards,


      Peter

    • Adisa
      Subscriber

      Peter,



       The value of stress in your results are the bigger then by hand. Because? it is because shear stress?


      And when will be the Von Mises used for comparing with the hand calculation?

    • ssridhar
      Ansys Employee

      Hi Adisa,


      In addition to the geometry changes that Peter pointed out, consider performing this as a 2D analysis. Here are the results that I got making the geometry changes + performing this as a 2D analysis. I think this way the out of plane Poisson's effect that might be present in a 3D model will be ignored.


      Sincerely,


      Raghav


       

    • peteroznewman
      Subscriber

      Hi Adisa,


      Your mistake is the length for the moment is to the neutral axis of the vertical member, which is 8 mm.



      As you can see, my ANSYS model gave very good agreement with the textbook.


      Kind regards,


      Peter


       

    • Adisa
      Subscriber

      Peter, can you see the analysis of the first post. I got the results of bending  stress  on the longer beam.


      Best regards.

    • peteroznewman
      Subscriber

      Adisa,


      The equations you showed above are for the combined bending and axial load on the short vertical column and are reported as Normal Stress in the Y direction.


      The bending stress on the longer beam would be the Normal Stress in the X direction and the simple handbook equation you show for bending stress is correct for the straight section. Once you get to the radius section, that equation is not sufficient.


      Kind regards,


      Peter


       

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