General Mechanical

General Mechanical

Membrane element problem in soft pnuematic actuator (artificial muscle)

    • itlezaza
      Subscriber

      Dear All,

      I'm trying to simulate a soft pnuematic actuator (artificial muscle) with two components, Skeleton cover by Skin, and operate with vacuum pressure inside to create contraction and generate force.

    • peteroznewman
      Subscriber
      I think your skeleton needs hinges to operate the way you want. You could either have four flat plates and use a Revolute Joint to provide a simple hinge, or you could just make the material at each end of the flat plate much thinner so it can bend easily.
      I recommend the flat plates be shell elements meshed on surfaces. You don't need a solid body for the W part of the skeleton.
    • itlezaza
      Subscriber
      Thank for your respone. I've tried simulate only skeleton by applying displacement to it and it works with some constraint. So, I think the problem is at the skin. About setting, contact or something else, I'm not sure.
    • itlezaza
      Subscriber
      Thank for your respone. I've tried simulate only skeleton by applying displacement to it and it works with some constraint. So, I think the problem is at the skin. About setting, contact or something else, I'm not sure.
    • itlezaza
      Subscriber
      Thank for your respone. I've tried simulate only skeleton by applying displacement to it and it works with some constraint. So, I think the problem is at the skin about setting, contact or something else.
    • itlezaza
      Subscriber
      Thank for your respone. I've tried simulate only skeleton by applying displacement to it and it works with some constraint. So, I think the problem is at the skin about setting, contact or something else.
    • peteroznewman
      Subscriber
      This model has very complicated contact conditions so it would be a good candidate to use the Explicit Dynamics solver. That solver automatically creates contact between all parts including part self contact.
      If you are willing to share your model, please create an archive file and attach the .wbpz file to your reply.
    • itlezaza
      Subscriber
      By the way, I've tried to simulate only skin or skin with cylinder inside as shown. I also get an error while contact isn't occur.
      So, I still think that problem is at the skin setting but I will follow your advice by trying to do this in explicit dynamics.
    • itlezaza
      Subscriber
      Sorry about my duplicated comment. I send my comment a lot but it still not appear. I'm not sure my comment was sent or not, so I resend it again and again.
      This is my files. I have to split it into two parts because of file size.
      I have two model in my project.
      I'm still confusing about contact, I define frictionless contact to all surface in the model, is that not enough?

      For your Information, I follow this process in the paper in my model.
      Ref: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7983108/
    • peteroznewman
      Subscriber
      I tried a variation of your model in Explicit Dynamics. The skin makes contact with the solid body, but the structure got 1 mm longer not shorter!
      Note: I increased the density of the two materials by a factor of 10 to speed up the computation time in Explicit Dynamics.
    • itlezaza
      Subscriber
      I think it elongated because you didn't apply pressure at the other end that is not fixed support. By the way, I try to do it in your file but geometry selection is still yellow and I can't run it.
      I also have tried this in explicit dynamics. It seems like it works but this error occur before the end of simulation and all of result is disappear.
      This is what I got from deformation plot tracker.
      Do you know how to fix it?
    • peteroznewman
      Subscriber
      Did you run out of disk space?
    • peteroznewman
      Subscriber
      I added pressure to some faces of the skeleton to represent the pressure on the end face of the skin which won't accept a pressure input. I don't know why.
      The solution stopped before it applied the full load due to the energy error being too high.
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