Axial loading (displacement)

Hi everyone,

I am new to ansys and would like to know how to do a simulation (compression test) on my bone model. How do i do with the analysis setting and displacement? Also, how do i make the platen rigid? Could anyone kindly help me out?

Thank you in advance.


Best regards,

Sin Yin

Comments

  • peteroznewmanpeteroznewman Member
    edited November 22

    @sinyin

    Find the platen body in the outline and in the Details window, you can change the Stiffness Behavior from Flexible to Rigid.

    Add a frictional contact between the bottom face of the platen and the face of the bone. You must pick the platen face to be the Target and the bone face to be the Contact side of the contact pair.

    Under the Connections folder, insert a Contact Tool and Evaluate Initial Contact Status. The contact must show as Closed. If it is Near Open with a tiny gap, edit the Contact and under Geometric Modification, Interface Treatment, use Adjust to Touch.

    Add a Remote Displacement to the top face of the platen. Change all values from Free to 0 to hold the platen fixed, except for the Y displacement, which you will make -2 mm.

    Add a Fixed Support to the bottom face of the bone.

    Under Analysis Settings, turn on Large Deflection.

    Under Step Controls, set Auto Time Stepping to On

    Make the Initial Substeps to be 100.

  • Hi @peteroznewman , can I make Y displacement -10mm instead?

    Under analysis setting, may i know if i should keep the other step controls as:

    No. Of steps = 1

    Current step number = 1

    Step End Time = 1.s

    Minimum substeps = 10

    Maximum substeps = 100

  • For this step: Add a frictional contact between the bottom face of the platen.

    Is it ok to input friction coefficient value as 0?

  • peteroznewmanpeteroznewman Member
    edited November 23

    @sinyin

    Yes, try -10 mm, but only after you see -2 mm converge. If -2 converges by -10 doesn't, then make it a 2-step solution and -10 can be the displacement in step 2.

    I recommend you try the solution with a friction coefficient of 0.1 because that helps to stabilize the structure. But you can try to solve with a 0 value instead.

    For screen snapshots, it is better if you learn to use the Windows Snipping Tool rather than your cellphone camera to insert images into the forum.

  • @peteroznewman , i tried -10mm with 2 steps, but it still does not converge. There is no problem with -2mm.

    There is also warning message: One or more MPC contact regions or remote boundary conditions may have conflicts with other applied boundary conditions or other contact or symmetry regions.

  • @sinyin Try making step 2 be -4 mm and see if that converges.

    That is a common warning and is often safe to ignore once you have seen that the solution is behaving the way you expect. However, by carefully applying contact and boundary conditions, you can avoid getting this warning.

  • @peteroznewman it does not converge with -4mm at step 2.

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