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Ansys Learning Forum › Forums › Discuss Simulation › LS Dyna › applying gravity and earthquake in z direction › Reply To: applying gravity and earthquake in z direction

May 7, 2024 at 10:43 pm
Maryam Tabbakhh
Subscriber

Dear Ushnish,

I tried SPC with death/birth. I put an spc for the nodes at the bottom (except corners) of the tank during gravity initialization (0-5) then I removed that and applied earthquake to the bottom corner nodes. It got unstable and the run didn't go thorugh (by decreasing time step to -20). I tried to apply the earthquake to the same node set but it didn't work. It gives me an error that this node has spc birth death  *** Error 10902 (KEY+902)
     Node ID 81 has spc's applied with different
     death time with *BOUNDARY_SPC cards 0 and 0.

Apparently I can't apply prescribed motion set and spc birth/death to the same node set. So I devide the bottom nodes to two groups (one I applied x,y,z DOE via birth/death spc (which will finish after gravity initialization) and the other one x,y which is availale throughout the whole analysis. what is your recommendation? Thanks 

*BOUNDARY_PRESCRIBED_MOTION_SET_ID
         1earthquake z
         3         3         1       222       0.5         01.00000E28       0.0

 

*BOUNDARY_SPC_SET_BIRTH_DEATH
         3         0         1         1         1         1         1         1
       0.0       0.5