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  1. bues0022

    How to define RSURFU

    Thanks for the offer Rob. I understand what you are saying by creating a rigid part and translating it towards the tissue rather than stretching the balloon. In your opinion, how much different will the solutions be? I am trying to mimic my experimental testing as closely as possible in which I...
  2. bues0022

    How to define RSURFU

    Well, first off I think I need to do a slight correction. The material is tissue, but not a vessel - it's a thin cross-section of tissue. Think of it like poking a whole in a shirt, and balloon-expanding that small hole. There likely will be some hourglassing. The last thing you said: "If all...
  3. bues0022

    How to define RSURFU

    Rob- Thanks for the help and thoughts. I think perhaps I should have explained some things a little better... I have a large series of simulations where I applied the load directly to the center ID. It's interesting you were able to get that to run so quickly, I had problems running it in...
  4. bues0022

    How to define RSURFU

    Update: I think I have some things figure out, but my model won't run. I'm getting an error: ErrElemMissingSection. I'm fairly certain that my model is defined correctly - but I'm obviously wrong though. I have my input file attached here. Can someone please run it and let me know what I have...
  5. bues0022

    How to define RSURFU

    I'm having a bit of a hard time attempting to define an RSURFU. I don't actually know where to start on it. I've tried doing some internet searching, but I can't figure out how to define it. I basically have a quarter-symmetry model of a washer, and want to expand the ID to a larger diameter. I...
  6. bues0022

    BC in cylindrical coordinates

    I'll check into that, thanks for the tip. I think I could probably wrestle with one line of code!
  7. bues0022

    BC in cylindrical coordinates

    If you don't mind me bringing this issue up again and hijacking your thread.... I am doing a very similar analysis. I have a quarter symmetry model of a washer. I am putting a cylindrical displacement BC to the ID in the first displacement step. However, I cannot use the X- and Y-symmetry BC's...
  8. bues0022

    Help selecting element- hyperelastic, adaptive meshing

    Here's an input file that I generated that ran, but with ABAQUS standard C3D8R elements with Relax Stiffness for the hourglass control. This file was ran on my laptop, so the mesh is fairly coarse. I'd like to get it to run on the large servers, but their machines for some reason don't like the...
  9. bues0022

    Help selecting element- hyperelastic, adaptive meshing

    Sorry about the ambiguity. I wrote the question the other day in frustration and now realize that I didn't include many details. Yes, I am using ABAQUS. I'll get a simplified model posted soon. I am basically attempting to deform a piece of neoprene under a pressure load. I am using Marlow after...
  10. bues0022

    Help selecting element- hyperelastic, adaptive meshing

    I need some help getting an element to work in my analysis. I am using a marlow hyperelastic material and am attempting to use ALE also. I can't seem to get any elements to work. I first attempted a brick element - C3D8R, and the error said that hyperelastic and hourglass control are not...
  11. bues0022

    Need advice getting either Standard/Explicit to converge

    I think I may have figured out my problem. I kept getting errors and the simulation would quit at about 85%. I tried the maximum pressure of 150,000 Pa instead of 200,000 - and the simulation completed without any problem. 0.15Mpa is 75% of .2Mpa which is less than the 85% where the model used...
  12. bues0022

    Need advice getting either Standard/Explicit to converge

    Alright, so I've made all the changes that were suggested, and I still can't get my model to comlete at 30Psi. My model makes it to 87%, then fails. Why? I get an error that says my material is unstable, does that have something to do with it? I'm confused since this isn't that complex of a...
  13. bues0022

    Need advice getting either Standard/Explicit to converge

    I was away from internet access over the weekend, so here's an update: I am getting results! Ramping the load from 0 to full over the entire time period. This is helping reduce "rippling" of pressure waves. I am using adaptive meshing, it seems to be helping because I no longer get errors of...
  14. bues0022

    Need advice getting either Standard/Explicit to converge

    1) I didn't know that even if I put in the stress/strain data for a hypelastuc material that I still needed to choose a model type and input the coefficients. I'll take a look at it. Also, I specified density, but not Poisson's ratio, explicit says it input a standard one for me. This seems odd...
  15. bues0022

    Need advice getting either Standard/Explicit to converge

    I tried using adaptive meshing with the Explicit solver, but ran into errors with element selection. I am trying to also find out what element I should use with hyperelastic materials, AND adaptive meshing. Any thoughts?
  16. bues0022

    Need advice getting either Standard/Explicit to converge

    This is the ABAQUS Explicit model I am working with.http://files.engineering.com/getfile.aspx?folder=c4eb1346-f2aa-47df-b3b6-26831bf2c246&file=rough_test_090616_explicit_test-case.cae
  17. bues0022

    Need advice getting either Standard/Explicit to converge

    This is the ABAQUS Standard model I am working with.http://files.engineering.com/getfile.aspx?folder=cb2e3f76-dc73-4e06-8c2a-dc2be0428621&file=rough_test_090616.cae
  18. bues0022

    Need advice getting either Standard/Explicit to converge

    My material model is a stress/strain data set that has been pull-tested to breakage. I do not see strain levels past my material model. I haven't yet tried using adaptive meshing in Standard, is that something that might help convergence with a higher load? I ran another model in Explicit...
  19. bues0022

    Need advice getting either Standard/Explicit to converge

    I am having some troubles with my model and am hoping that someone on here can lend some advice. I am attempting to model a balloon-expansion of tissue. My model consists of a 1/4 geometry "donut" of material. The ID (initial incision point) is 5mm, thickness=5mm. I want to expand out at 30 PSI...

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