General Mechanical

General Mechanical

a question about beam element stiffness matrix

    • 567
      Subscriber

      I've exported the stiffness matrix of a beam element. but the value is not equal to my calculation. and I've calculated the size of the beam element based on the value of stiffness matrix. the result is not equal to my set.

      this is the apdl command line:

      finish
      /clear
      /PREP7
      
      
      /NUMBER,-1
      /VIEW,1,1,1,1
      /ANG,1
      
      
      ET,1,BEAM188 ! BEAM
      SECTYPE,1,BEAM,CSOLID
      SECDATA,0.003,120
      MP,EX ,1,2.07E11
      MP,PRXY,1,0.3
      MP,DENS,1,7800
      
      
      N,1,0,0,0
      N,2,0.1,0,0
      
      
      TYPE,1
      MAT,1
      SECNUM,1
      
      
      E,1,2
      
      
      D,1,ALL
      
      
      
      
      /SOLU
      
      
      ANTYPE,2
      MODOPT,LANB,10
      MXPAND,10,,,0
      SOLVE
      

      this is the result:

    • Erik Kostson
      Ansys Employee
      The stiffness matrix you are showing in the image above (e.g., 12*E*I/L^3) is for an Euler beam theory.

      The old legacy Euler-Bernoulli beam is called BEAM4 - so you would need to use this element in order to compare to the above equation.



      Hope this helps

      All the best

      Erik
    • 567
      Subscriber

      this is it, but There's too much deviation. I think this is not correct, thanks for your reply
    • 567
      Subscriber

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