I have run a simulation on a 5-foot rod with two plates attached to it as seen below. First, I ran a simulation of a hollow rod, and then I ran a study of a solid rod. I upload a shock profile from a plot that I found in MIL-STD 810G.

For some weird reason, I got more deflection from the response spectrum analysis of the solid rod. This seems backwards to me. Should a hollow rod deflect more if subjected to a shock load?