I've been trying to simulate the force transmissibility experiment based on the setup shown in the attached diagram where the transmissibility is defined as the ratio of transmitted force (measured by bottom force sensor) to the exerted force (measured by top force sensor).

I've used a fixed support boundary condition (BC) on the lower face of the bottom force distribution plate and a remote displacement/displacement BC to the upper face of the top force distribution plate. I used these BCs as I believed they are the closest to the real experimental conditions used.

to measure the force, I used force reaction probes on these boundary conditions. Then, I manually plotted the transmissibility ratio ( force reaction measured from the bottom to top plates).

However, the graphs obtained are nowhere near the normal transmissibility curves.

I also tried this way by using frequency response for the top and bottom plates and used the generated amplitudes to manually plotted the transmissibility ratio, however, I did not manage to do this as the frequency response from the top plate is zero (shown in attached figures).