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Failure Criterion for Materials

Roland
2013-10-15
2013-10-23
  • Roland

    Roland - 2013-10-15

    Dear all,

    First of all, thank a lot for the great FEM tool. First simulations of penetration setups look fine and I am looking forward to validate the tool with other FEM software.
    I have a bunch of small questions:

    For the parameter FAILURE_STRESS and FAILURE_STRENGTH, which components or invariants of the stress/strain are used?

    For the parameter FACTOR and THICKNESS (at Contract_Triangle-Command), which units for the values are used? The default units (i.e. KN or mm) or are relative units (p.e. relative to some mesh element lengths)

    Roland

     
  • Waluyo Adi Siswanto

    I think there are two failure: FAILURE_STRAIN and FAILURE_STRESS
    There is no FAILURE_STRENGTH

    The thickness unit used in contact triangle should be consistent with other length unit,
    the consistent unit list: http://www.impact-fem.org/doc_fembic_en#units

    WAS

     
  • Roland

    Roland - 2013-10-18

    Hi Waluyo

    Sorry, FAILURE_STRESS is correct. My question is the following: What is the detailled failure criterion implemented in the code? Is it the maximal stress/strain criterion (i.e. all principal stress<FAILURE_STRESS) or the von mises yield criterion, or... ?

    Can you propose any literature reference on this topic?

    Bests, Roland

     
  • Waluyo Adi Siswanto

    fstrain: The strain at which the material fractures. If an element reaches this strain, it will be removed from the simulation.

    fstress: The stress at which the material fractures. If an element reaches this stress, it will be removed from the simulation.

    http://www.impact-fem.org/doc_fembic_en#materials

    WAS

     
    • Roland

      Roland - 2013-10-23

      Dear Wayulo,

      Thank for your reply. I am award of the fembic-definition of fstrain and fstress. But: Which kind of stress (or strain) will be used for evaluation of the fstrain/fstress ? For example, one could be used the Si stress-component, or the maximum of all invariants or a combination of the six stress components.
      Maybe you just have a liturature reference or a reference to the IMPACT-code?

      Bests, Roland

       

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