Electromagnetic Powder compaction using LS-DYNA

Dear all,

I am currently undergoing research on simulating Al powder compaction with electromagnetic Lorentz forces using LS-DYNA. As I am new to this software, I need some guidance on it. I had read through the manual but it didn't help much. 

Below are my few enquiries:

1) The density required in the material parameter is the initial density or the bulk density of the Al powder? If I use relative density, can I input in LS-DYNA and how do I do that?

2) I wanted to use Druker Prager to model my simulation. The result obtained is in Mises stress. However, my supervisor said it is supposed to be in Drucker Prager values. Can anyone clarify this?

If anyone has a related article on this subject, can you share it with me?

Thank you so much,