LS Dyna

LS Dyna

How to achieve better conformity between a stl part and a solid part ?

    • Yspartan
      Subscriber

      Hello,

      I am running a helmet simulation in which I need liner pad to have bonded connections with the hard outershell of the helmet, however due to the line pad being a complex lattice structure the conformity of the external surface of the pad with the inner surface of outer shell not very good. This creates issues with getting the parts to be bonded. I tried increasing the offset value for the bonded connections but that gives time step error and sometimes high energy error. The outershell is 0.5 mm thick and is all shell elements whereas the pad is all tet elements.

      Can I replace bonded connections with frictional with high frictional value of say 0.9 to resolve this issue? Is there a way to get the bonded connection to work without giving errors?

    • Chris Quan
      Ansys Employee
      The time step error is usually caused by distorted elements. The high energy error is also related to distorted elements or other issues with model setup.
      It may not be the bonded connection that caused the problem with time step or energy error.
      It is true that the increased value of maximum offset can have more nodes/faces being bonded.
      You can apply both bonded and frictional contacts to the outer shell and liner pad. Program will bond the nodes/faces where their distance is less than the maximum offset.
      For the nodes/faces where their distance is greater than the maximum offset, program will apply frictional contact automatically.

    • Yspartan
      Subscriber
      Thanks for the insight. Did try it and it seems that the solution progresses without too much error.
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