Hello guys 🙂
I am kind of new in LS Dyna. So, sorry in advance if it is an easyyy or dumb question. anyway..
I need to model stacked compression test. I am done with everything. However, I have all the time negative sliding energy. I know it has to be positive. I was taking initial penetrations errors at first place then I corrected them. Now, it is not written anything with initial penetrations but I can not understand then what was the reason. I checked Ls Dyna support page and tried to apply all solutions except mass scaling and time step scale factor.
So, what is your opinion on this topic? Thank you so much in advance.
Stay healthyyyy.
Hi @agentcooper,
I apologize for not seeing this. Sliding energy is just contact energy, so yes negative sliding energy usually occurs from initial intersections between meshes in contact with each other or through penetrations with the thickness of shell elements. Intersections are physical overlaps between meshes in a contact and penetractions are just the projected thickness passing through a mesh. You should never have intersections.
Penetrations can cause issues depending on your *Control_contact settings. Make sure you set IGNORE in *Control_Contact to 1 or 2, which ignores initial penetrations. By default this is 0 which will cause dyna to move the mesh to avoid these, which might be causing weird energy in your simulation.