Dear Prof. David Mašín

Greetings

I would like to discuss with you an issue. I have a problem in my simulation on ABAQUS. The problem in the simulation results is that the strain is so small, For experimental results i have the maximum axial strain = 12% but for my simulation on ABAQUS the Max. Axial Strain = 0.10% and the deviator stress is correct in both. ( I’m using Hypoplastic Model and i’m making a simulation for Triaxial test under monotonic loading)

In your opinion what should i check to solve this problem of the strain in my model ? i put the intergranualr strain = 0 like the article of performing PLAXIS using hypoplastic model

Thank you very much
Mahmoud

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3 Comments
  1. Piotr Kowalczyk
    Piotr Kowalczyk 7 months ago

    Hey Mahmoud

    I also use hypoplastic model (sand). I would just say that your calibration needs to be readjusted. The stiffness in hypoplastic model is controlled as far as I remember by mainly but two parameters: hs and n. I would start with playing with those two numbers to see what you get.

    In the download package, I believe, there are papers which give common ranges for those two parameters so you can get some idea on how to change those two values.

    Hope this helps a bit.

    Piotr

  2. Mahmoud Hamed Author
    Mahmoud Hamed 7 months ago

    Ciao Piotr

    Thank you very much for this information

    I just would like to know what should be the range of hs and n as well ?
    what do you mean by the download package ? can you send to me any paper that include these ranges ?

    Thank you again
    Mahmoud

  3. Piotr Kowalczyk
    Piotr Kowalczyk 7 months ago

    Hey

    Look at Herle, Gudeus (1997) which is available in the section where you can download HP umat on soilinfo.com. Table 7 gives calibration of HP model for various sands. There you can see what is the range of values of hs and n.

    If this is not enough for you can try to search for papers on modelling centrifuge tunnel tests with hypoplastic model by Wegener, Herle (2014?). They actually calibrate HP model with quite different values of hs and n. I do not know why these differ quite significantly from the usual values. Maybe small strain behaviour needs to be calibrated with a separate set of parameters. But I am absolutely not sure about that! Hopefully, some other people will advise more.

    Good luck.

    Ciao

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