Hypoplastic Interface Model: Virtual Shear Zone Thickness and Surface Rougness Coefficient

||Constitutive Modelling|9 |
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Hello,

I want to use Hypoplastic Interface (Fric Subroutine) in my ABAQUS contact models. However, I don’t know how I can determine Virtual Shear Zone Thickness. It is the Parameter #24 in the FRIC subroutine Manual. Is there a simple rule of thumb to determine this parameter? Same question also goes for Surface Rougness Coefficient (Parameter #23).

Thanks.

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9 Comments
  1. Hans Henning Stutz
    Hans Henning Stutz 7 years ago

    Thank you for your post. The virtual shear zone thickness dependent on the charateristic length of the element. I would suggest in the first step that you use ds = 1.0. Please have in mind the virtual thickness is a critical parameter input for the hypoplastic interface model.

    The shear zone thickness I took from the following reference:

    Arnold, M. (2008). Application of the Intergranular Strain Concept to the Hypoplastic Modelling of Non-Adhesive Interfaces. In The 12th International Conference of International Association for Computer Methods and Advances in Geomechanics (IACMAG) (pp. 747–754).

    and have a look about page 751. Arnold described the calibration procedure. In short:
    The parameter kappa_r controls the evolution of shear stresses and the virtual interface thickness ds_v is a scalar for the displacements. The parameters can be obtained by back calculation. Arnold proposed to use two computations: 1. The first with kappa_r = 1 and ds_v = 1. The parameter kappa_r is then approximately the ratio between the peak shear strength and the peak shear strength. This kappa_r is used in the second run to scale the displacements, ds_v can then be chosen to fit the test data.

    If you have any further question please don´t ask.

    Regards,
    Hans Henning

  2. Hans Henning Stutz
    Hans Henning Stutz 7 years ago

    Sorry, I forget two words in the last sentence:

    If you have any further question please don´t hesitate to ask.

    • Mahmoud Hamed
      Mahmoud Hamed 5 years ago

      Hello Dr. Hans
      It is written in the PDF named ” Implementation of hypoplastic granular interface models using
      FRIC subroutine ” exactly at ( 5 Trouble shooting ) that:

      ” 2D and axial-symmetric simulations:
      The interface model is currently only available for 3D simulations”

      To avoid the misunderstanding, do you mean that i can not use ( only) FRIC Subroutine if i will use axial-symmetric option but i can use it normaly for UMAT Subroutine ? or i can not overall use axial-symmetric option with any Subroutine ?

      Thanks in Advance,
      Mahmoud HAMED
      3SR Laboratoire, université de grenoble alpes, FRANCE

      • Hans Henning Stutz
        Hans Henning Stutz 5 years ago

        Dear Mahmoud,

        This means the subroutine (FRIC) can be only used in 3D simulations (no plane strain or axial symmetric).
        I have a modified version, I will try to uploaded in the next week.

        Best,
        Hans

  3. Mahmoud Hamed
    Mahmoud Hamed 5 years ago

    Dear Prof. Hans

    Thanks for your quick response.

    So, i will continue using UMAT Subroutine with axial-symmetric option because 3D simulation takes time.

    I have another inaquire if you don’t mind, For UMAT subroutine in ABAQUS ( I downloaded it which belong to Prof. David Mašín), i should put Number of 22 Parameters for the Mechanical constants in order as mentioned in this Link :
    https://web.natur.cuni.cz/uhigug/masin/plaxumat/node5.html

    The question here, Should i also put the interface parameters ( From 23 to 26) mentioned in your PDF
    ( Implementation of hypoplastic granular interface models using FRIC subroutine ) to the UMAT subroutine? or parameters from 23 to 26 are only belong to FRIC subroutine ?

    Thank you again for your help
    Kind Regards,
    Mahmoud HAMED

    • Hans Henning Stutz
      Hans Henning Stutz 5 years ago

      Dear Mahmoud,

      If you only use the Umat in the Materials use only 22 parameters, if you use the Fric subroutine you should use 26.

      Best regards,
      Hans

      • Naif Alsanabani
        Naif Alsanabani 5 years ago

        Dear Dr. Hans
        I simulated soil in Abaqus by using hypoplastic model. currently, I tried to model block foundation on saturated sand, type of loading that subjected on the foundation is cyclic loads.
        To obtain a homogenous model system, the interaction of structure-soil interface should be considered by using hypoplastic interface.
        Could you provide me Fric of hypoplastic interface code please?

        Best regards.
        Naif Mohammed

      • Hans Henning Stutz
        Hans Henning Stutz 5 years ago

        Dear Naif,

        Please check: https://soilmodels.com/hypointerface/

        Regards,
        Hans Henning Stutz

  4. Naif Alsanabani
    Naif Alsanabani 5 years ago

    Dear Dr. Hans
    Thanks for your quick response and helping.

    Best regards
    Naif Mohammed

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