Hi everyone,
I'm currently evaluating a tube-fitting (adapter) made out of plastic. The pipes that the adapter connects is made out of steel.

The problem is when a person by mistake puts a load on the pipes they tend to break the adapter. Now I'm evaluating a new design or possibly a new material

The problem:

I've made the conclusion that the easiest way is to perform the analysis in an assmebly with the pipes present inside the adapter.

-Put the load on one pipe,

-fix the other one

-and by contact boundary condition (no penetration) get the loads/strains in the adapter. (see attached PDF)

I woluld like to skip the assembly-step and just do the assumptions with "smart" BCs, do you guys have any tips regarding this?
Otherwise, please help me find whats wrong with my current BCs since I get almost no stress/load transfer out to the adapter part.