General Mechanical

General Mechanical

Load Displacement Curve

    • Didar Mei
      Subscriber

      Hello! I am beginner in ANSYS. I am analyzing a column that is connected to the base by welding as can be seen below. I applied 300 mm z-direction displacement on the top face of the column and added fixed support at the bottom face of the base. I assigned every connections. Now, I want to draw a load-displacement curve to verify the experimental results. The reaction force from the displacement and the directional deformation at the z-axis of the top edge of the column were used to derive the load-displacement curve. However, the load keeps increasing rather than going down after reaching the ultimate load as in the experiment. I defined the nonlinear properties of the used steel by assigning isotropic multilinear hardening. What can be the problem?

       

    • Ashish Khemka
      Ansys Employee

      Hi Didar,

       

      Please check if you assigned the correct material model to the body. Also, please share the snapshots of material defined in Engineering Data and the result of reaction force against displacement. By the way, did you turn on the large deflection on?

       

      Regards,

      Ashish Khemka

      • Didar Mei
        Subscriber

        Dear Mr. Ashish Khemka,

        Thank you for your reply. I turned on the large deflection. Below, I attached material models from engineering data. I used 3 materials, posmac 4 for the column, posmac 10 for the ribs and base, and stainless steel for bolts and nuts. Moreover, I attached a load-displacement curve that compares experimental and numerical results.

        Best regards,

        Didar Meiramov

    • Didar Mei
      Subscriber

      Dear Mr. Ashish Khemka,

      Thank you for your reply. I turned on the large deflection. Below, I attached material models from engineering data. I used 3 materials, posmac 4 for the column, posmac 10 for the ribs and base, and stainless steel for bolts and nuts. Moreover, I attached a load-displacement curve that compares experimental and numerical results.

      Best regards,

      Didar Meiramov

        

    • Ashish Khemka
      Ansys Employee

      Hi Didar,

       

      Can you try refining the mesh and see if the stress level increases?

       

      Regards,

      Ashish Khemka

      • Didar Mei
        Subscriber

        Hello, Sir!

        Below, I derived von Mises stress - total strain results from the node that experiences one of the max stress under displacement. From the graph, it can be seen that there is a difference in the plastic behavior of the material at the initial steps. This could be explained by converting experimental data to engineering data. However, while the material fails in the experiment, the ansys material behavior still continues. Does this phenomenon mean that I should use the damaged properties of the material for the used steel (Johnson Cook model)? Below, I attached all my results, and refined mesh pictures also. Moreover, should I use explicit dynamics for my model?

        Best regards,

        Didar Meiramov

        The above graph shows the material behavior of the experimental vs Ansys stress-strain relationship.  

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