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Contact tiebreak separation issues with curved surfaces

    • Vinay Shekhar

      Hi everyone, 

      I am attempting to model a layered GFRP structure with curved surfaces. I chose to use layers of thin shells tied together with the CONTACT_AUTOMATIC_ONE_WAY_SURFACE_TO_SURFACE_TIEBREAK cards.

      I generated the geometry for each layer in a CAD package, exported it as STEP files, and then meshed each layer inside LS-PrePost. 

      The current problem I am facing is that the due to the curvature of the structure, the shell layer offset is not exact. In this problem, I have set the layer offset at 0.64 mm, but the measured offset is between 0.63996 mm and 0.64005 mm. This fifth significant figure discrepancy is causing the tied contacts to fail prematurely with a number of initial penetration warnings from the LS-DYNA solver. 

      Any advice on how to tackle this problem would be greatly appreciated. Including the possibility of using other contact cards that can do the same job.  

    • Andreas Koutras
      Ansys Employee


      Could you increase the contact thickness a bit further so that there is some initial penetration throughout the surface. To modify the contact thickness, you can use SAST or SBST on *CONTACT. I tried it with tiebreak OPTION=11 in MPP and seems to be working. Running a test with a flat contact surface will help confirm this.

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