Modal Analysis of press fit shaft hub assembly

Hello All,

for my master project i need to do Modal analysis of press fiit shaft hub connection to find natural frequencies. I have used friction free contact for the press fit simulation.

1. I found that the differnce between calculated contact pressure and simulated contact pressure is large

2. As the contact interfaces in Modal analysis are ignored, i am trying to idealize the press fit interface by spring, But can anyone please explain how may i calculate the stiffness of spring for press fit interface, or is there any other method to perform modal analysis for press fit.

I ghave attached the CAD files and mathcad calculation in the folder. Any suggestions would be appreciated.