fem analysis with bolted connections

[leonardo-037]

Hello everyone, I've been stuck in the design of a cnc machine by self-build.
I would like to do a fem analysis of the parts that are obviously all bolted together.
the bolts will be formed by screw + washer then the two plates to be fixed and then washer+dado on the other side to complete the bolt.
for simplicity place an image where are represented two generic plates with the matching holes in which the bolts will go.
not having a computer quite satisfactory I decided to simplify the fem analysis, so instead of the bolts I put only the two washers and two equal and contrary forces applied on the outer superfieci of the two washers that simulate the bolt tightening.
the real problem I'm finding is the correct use of contacts
you which contacts you would put between:

1: Washer - plate 1
2: plate 1 - plate 2
3: plate 2 - back washer

I tried to make contact with separation between the two plates and glued between the plate and the washer but acting gravity perpendicularly to the axis of the generic bolt the analysis gives me error.(practically the two plates to tighten give vertically to each other)

I hope I've explained as much as possible.

 

[leonardo-037]

I also tried to glue between all surfaces.... the analysis is completed but the results do not know if they are reliable because in fact the surfaces are all separate.....
putting on instead always glued between the washer and plate and contact separation no sliding between the two plates, inventor completes my analysis but the two plates are detached....
a final clarification.... all analyses are carried out with only gravity agent...... without forces to simulate bolts because unfortunately not quantitatively the force to be applied.....
I would first like to make sure that the contacts are defined exactly before trying to deal with the calculation of the clamping forces. . .