Brain drop simulation

I am doing research involving the finite element modeling of a human head namely Scalp, Skull, Brain & Duramater using Abaqus/CAE. I have finished modeling the parts, assigning the material properties, assembling and meshing the said model. I need to drop the whole assembly onto a 'floor'. What step should I choose. Also what interaction would I have to create so that the head would shear when it is dropped a distance less than 1 cm. Also bear in mind that it should not bounce.

 Thank you.