I need some advice on how to proceed here.  I'm bringing a mass going at a specific speed to a stop, using a bumper mounted on a bracket.  I have the force/deflection curve for the bumper.  

I know I need to use a nonlinear analysis.  How to model the mass coming in?   Do I use an assembly with a blob to represent the mass, and a spring between the blob and the bracket?  How to set up the initial conditions and the time steps?  

Is this a dynamic analysis, a nonlinear, or a combination of both?

There's amazingly little information out there, other than "take a course."  Fair enough. Which course to take?

FWIW, my company also uses plastic parts, so the nonlinear course would be handy.  But the impact is what I need.