General Mechanical

General Mechanical

negative load-displacement curve

    • jjaafar68

      Dear all, 


      I'm using Ansys Apdl v16 to model simple concrete beam under static load by using Solid65 element.

      after plot load-displacement curve , the curve stopped at the maximum load, unlike experimental there are no negative slope in the curve. 

      my question is, 

      is there any way to plot full load-displacement curve with the negative slope ? like the graph. 


    • mekafime


      I usually change the sign in excel

    • Sandeep Medikonda
      Ansys Employee

      Hi, Isn't that post-buckling behavior?

      Did your model run to completion? I suspect it hasn't?

      Buckling is a numerical stability and your tangent stiffness matrix is going to zero.

      You can overcome buckling by adding some stabilization energy to your model.



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    • peteroznewman

      What was the load in your model: a force or a displacement?   A force load cannot solve past the maximum force, that is why it is required to have a displacement load on your structure and extract the reaction force. A displacement load can track a reaction force reaching a maximum and then plot the negative slope.



    • OguzhanA
      But if we have to apply environmental pressure (like external pressure) to a cylinder, we can't add displacement there, right?n
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