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).


  1. Hans Henning Stutz
    Hans Henning Stutz 3 weeks 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.

    Hans Henning

  2. Hans Henning Stutz
    Hans Henning Stutz 3 weeks ago

    Sorry, I forget two words in the last sentence:

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

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