LS Dyna

LS Dyna

Crash test explicit analysys of a composite structure

    • Marco000
      Subscriber

      I'm performing a simulation of a crash test on carbon fiber Structure using ansys explicit analysys module and ACP(pre); I have some problem with the process. I recap shortly what I've done:


      - Creating model of Carbon Fiber structure with ACP(pre) and share shell surface data in explicit analysys. The Material model has got density, orthotropic elasticity, orthotropic stress limit, Tsai-Wu constants. The Stress limit constants cames from previous material caraterization with static experimental tests.


      - Set up simulation like low speed simulation(7m/s) with initial velocity condition of a rigid impact plate and fixed the base of the carbon fiber structure.


      The problem now is:
      - When i disable material failure model I have a perfect elastic simulation with no problem o element distorsion.
      - When I use material failure model i have large distorsion of elements that incame in failure. I don't know if it is normal or is something like hourglassing mode. This preclude all the late results of simulation because it deforming the grid.
      - If i include Erosion: with geometric strain limit erosion(1,5) i obtain a stable simulation with bad results, the system desn't dissipate the Kinetic energy of the plate, it's far from reality; with failure material erosion I obtain somethings similar but i can't complete the simulation because everytime one element detached from the structure became so big and create problem.


      For now I disable the Energy error because it stops me every time, when I'll find a solution I'll come back in Energy controlling. I have quad dominant shell mesh: I try to reduce it's dimension (10mm-->6mm) and try to reduce the time steps safety factor without good results. How can I solve this problem?


      Marco S.


       


       

    • Gopi
      Subscriber
      I need your help regarding the ACP Ls Dyna Explicit Dynamics. When I doing three point bending analysis the the punch is going through the beam. If you wanna give suggestion. Please do
    • Marco000
      Subscriber

      Someone have an idea for stabilize shell element distorsion post failure? I have this problem yet.


      If I switch to solid element for include fracture softening how i can model solid layered structure without using ACP Pre/Post that can't transfer solid data to explicit dynamic module.

    • Meri
      Subscriber
      hello Gopi,nHave you found a solution for your simulation probel please? I am doing a car crash test and am having the same thing (car going through the wall) with same ACP (or Layered section)- LS Dyna EXplicit dynamics.nIf you have anything to help me with please suggest.n
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