LS Dyna

LS Dyna

Modelling Composite material with high impact velocity

    • Hamid Sarhan
      Subscriber

      Hi

      I am trying to model a composite material with high impact velocity. I have two questions, the first one is how to define the contact between the layers and the second is how to define local coordinate system for each layers ( the plate is not flat, it has curverture). 

       

      Thanks  

    • Jim Day
      Ansys Employee
      Are your layers modeled with solid elements as is implied by the image? Are the layers merged together via shared nodes at each layer interface? Do the material models include failure criteria such that elements may be deleted? Assuming yes to all questions, *CONTACT_ERODING_SINGLE_SURFACE with all the parts on SURFA (slave side) would be appropriate.
    • Jim Day
      Ansys Employee
      If you're talking about a local coordinate system for the purpose of orienting material directions in an orthotropic/anisotropic material model, no such system should be needed. The variable AOPT in the *MAT input may be set to 0, in which case the element coordinate system as determined by the nodal connectivity will serve to orient the material coordinate system. See Remarks in the description of *MAT_002 in the LS-DYNA User's Manual for details.
    • Hamid Sarhan
      Subscriber

      Thanks Jim for your response, in my simulation I assumed the composite material to be flate plate and for thsi case the *CONTACT_ERODING_SINGLE_SURFACE was working fine. However, when I tried to model the palte with curvature for same boundary conditions this model was not working. Now I assumed a zero cohesive layer between the different layers. In the experimental the impactor was not penetrated the plate but in my simulation the impactor is penetrated.

      More information

      The layers were modelled as solid elements and these layers were sperated by a zero thickness choesive layers 

      For Material model I used MAT_54/55 for the plates and MAT_138 for the cohesive layer

      The issue now even with the Cohesive layer the impactor is penetrating the plate, is there any advise that I can follow to overcome this problem

       

      Thanks in advance

       

    • Jim Day
      Ansys Employee
      For an example that may be of some help, go to https://awg.ansys.com/QA+test+example+7. Cohesive elements between layers or alternatively, tiebreak contact (*CONTACT_AUTOMATIC_ONE_WAY_SURFACE_TO_SURFACE_TIEBREAK) between layers, is needed to represent delamination. That's only one aspect of the problem. Accurate material characterization (choice of material model for the layers and populating that material model with input to match material test results) is imperative to obtaining good agreement between your simulation and a physical test. If you are a commercial customer, you should be able to share your model and obtain more personalized help beyond what can be provided within the scope of this forum. Contact your Ansys Channel Partner or visit https://customercenter.ansys.com/
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