Impact analysis - Energy Transfer

[flyforever85]

I'm running with ABAQUS explicit an impact analysis. It's a box that is dropped from 15 in on top of a honeycomb sandwich.
In the analysis I have:
1. set the box at the honeycomb surface and applied a velocity;
2. applied the boundary conditions and the general contact;
3. set the time of analysis for 2.8e-3 sec (which is the time to travel for 0.3 in)
4. I implemented Johnson Cook model parameters for both plastic deformation and ductile damage (I found some values on internet but I'm not sure how reliable they are)

The experiments show that the box dissipates all its vertical speed into plastic deformation of the honeycomb and fall on a side
The simulation shows that the box after 0.0028 sec has still plenty of speed (90%) and the deformation is already > 0.3 in. I run the simulation for a total time 4 times longer and the speed dropped to 40% of initial speed. How can I find the time necessary to dissipate all the velocity into plastic deformation?

 

[FEA way]

Apart from checking the velocity and deformation you can plot the plastic dissipation energy - total for the whole model (ALLPD) or separate value for each element (ELPD). What's more, you can use *EXTREME VALUE, HALT=YES or *FILTER, HALT to stop the analysis when specified value of selected output variable is reached. Both work only in explicit but in your case it's not a problem.

 

[flyforever85]

THank you, I will double check both

 

[DanStro]

Most of the time when I see things like this happen it is because I have the units incorrect. How confident are you about the units of your JC model? Are they the same (Pa,MPa,GPa...) as the rest of your model?