Modelling a confined cyclic compression of a biphasic system

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts
  • Thiago
    Junior Member
    • May 2020
    • 20

    Modelling a confined cyclic compression of a biphasic system

    Hello.
    We are simulating this kind of experiment: The bi-phasic sample is initially pre-compressed, then we give enough time to the sample to relax the stress and finally we apply a cyclic compression at a certain frequency.
    Since we need the contact interface between the sample and the piston to:
    a) allow fluids to flow through the interface
    b) don't pull the sample during the positive slope movement of each cycle
    it seems like a good solution would be to model the piston with two parts: a rigid body (that i can make move by defining the displacement at each step) connected with a rigid contact to a flat plate (with a very high E modulus to be considered not deformable) which is connected to the sample through a biphasic contact.
    So, is this a good approach for modelling this experiment?
    If this is a good approach, can you please help me to understand all the 'properties' we have to set in the biphasic contact?

    Thank you
  • ateshian
    Developer
    • Dec 2007
    • 1824

    #2
    Hi,

    You can model the piston with a rigid body only. There is no need to create an additional elastic material and attach it to the rigid body. You just need a mesh associated with the rigid body to define the contact surface. A planar surface will do for confined compression.

    Since you want the piston to allow fluid to flow through it, you can use the "sliding-elastic" contact interface and apply "fixed fluid pressure" boundary condition to the surface of the biphasic domain; this will allow for fluid to flow across that boundary. There is no need to use the "sliding-biphasic" contact interface.

    The recommended settings for "sliding-elastic": auto-penalty=yes, penalty= a number between 1 and 10, the higher value minimizes the overlap between the contact surfaces, two-pass = no. If you don't get good convergence with a higher penalty and if you get too much overlap with a lower penalty, then set laugon = yes and try the default setting for the tolerance.

    Best,

    Gerard

    Comment

    • Thiago
      Junior Member
      • May 2020
      • 20

      #3
      Hi Gerard, thanks for the response.

      Comment

      • Thiago
        Junior Member
        • May 2020
        • 20

        #4
        Hi all.
        We are conducting an analysis on the material's response under several values of (Frequency, Amplitude) of the applied single cycle cyclic compression. The model work well for certain values of F, A but runs into troubles when F>=1Hz and A>=5%h simultaneously, where h is the height of the sample. I already tried to refine the mesh and define smaller time steps as well, but this doesn't seem to be the solution to this error termination.
        I would really appreciate if you will take a look at my model and will tell me your opinion about it.

        NewModel2.0_job.feb
        Attached Files

        Comment

        Working...
        X
        😀
        😂
        🥰
        😘
        🤢
        😎
        😞
        😡
        👍
        👎