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 2 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 2 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 10 months 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 10 months 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 10 months 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 10 months 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 10 months 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 10 months ago

        Dear Naif,

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

        Regards,
        Hans Henning Stutz

  4. Naif Alsanabani
    Naif Alsanabani 10 months ago

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

    Best regards
    Naif Mohammed

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